Rhizobacter

Can J Microbiol, 1979 Mar, 25(3), 298 - 301
Phenotypic reversion of nitrogenase in pleiotropic mutants of Rhizobium meliloti; Barabas I et al.; In two out of three pleiotropic mutants of Rhizobium meliloti, defective in nitrate reductase induced by amino acid utilization in vegetative bacteria and in symbiotic nitrogen fixation, nitrogenase activity could be restored completely by purines and partially by the amino acids L-glutamate, L-aspartate, L-glutamine, and L-asparagine . The compounds restoring effectiveness in nitrogen fixation did not restore nitrate reductase activity in vegetative bacteria . The restoration of effectiveness supports our earlier conclusion that the mutation is not in the structural gene for a suggested common subunit of nitrogenase and nitrate reductase.

Mikrobiologiia, 1979 Mar-Apr, 48(2), 341 - 5
{Deformation of lucerne root hairs caused by the growth substances and culture broth filtrates of Rhizobium meliloti}; Shemakhanova NM; Deformation of lucerne root hairs caused by the action of beta-indolylacetic acid (IAA) and alpha-naphthylacetic acid (NAA) differs from deformation induced by Rhizobium meliloti . High concentrations of IAA brought about abnormal deformation of root hairs wherease the action of average concentrations of IAA resulted in corkscrew-like winding and wavy structures . No deformation was observed under the action of low IAA concentrations or the cultural broth of Rhizobium . Infective filaments in root hairs were found only upon infection with pure cultures of Rhizobium.

Mikrobiologiia, 1979 Mar-Apr, 48(2), 329 - 35
{Lysogeny of Rhizobium japonicum and the sensitivity of these cultures to phages isolated from soil}; Moskalenko LN et al.; Twenty cultures of Rhizobium japonicum of various origin were tested for lysogeny using a cross technique with a preliminary UV induction and without it as well as by electron microscopy . None of the cultures was found in the lysogenic state . Phages active against Rh . japonicum were detected in four soil samples on which soybean plants were grown; 27 phages were isolated by the enrichment method and 3 phages without enrichment . The phages were capable of lysis of only Rh . japonicum cultures and differed in the spectrum of lytic action . Some of them were very specific: 9 phages caused lysis of only one among the 28 tested cultures, and 10 phages lysed 2 cultures . Phages with a broad spectrum of lytic action induced lysis of 7-9 cultures . Some of the phages isolated from soils of different type were identical and some were similar in the spectrum of lytic action . Among 28 cultures of Rh . japonicum, 8 cultures were sensitive to all of the 30 phages isolated from soil and 2 cultures were sensitive to most of the phages; the remaining cultures were sensitive to 1-8 phages . Phages and cultures have been selected which can be used for experimental preparation of lysogenic systems and further studies of lysogeny in Rh . japonicum.

J Bacteriol, 1979 Mar, 137(3), 1362 - 73
Bacterial polysaccharide which binds Rhizobium trifolii to clover root hairs; Dazzo FB et al.; Immunofluorescence, quantitative immunoprecipitation, and inhibition of bacterial agglutination and passive hemagglutination indicate that cross-reactive antigenic determinants are present on the surface of Rhizobium trifolii and clover roots . These determinants are immunochemically unique to this Rhizobium-legume cross-inoculation group . The multivalent lectin trifoliin and antibody to the clover root antigenic determinants bind competitively to two acidic heteropolysaccharides isolated from capsular material of R . Trifolii 0403 . The major polysaccharide is an antigen which lacks heptose, 2-keto-3-deoxyoctulosonic acid, and endotoxic lipid A . The minor polysaccharide in the capsular material of R . Trifolii 0403 contains the same antigen in addition to heptose, 2-keto-3-deoxyoctonate, and lipid A . The acidic polysaccharides of two strains of R . trifolii share the clover r-ot cross-reactive antigenic determinant despite other differences in their carbohydrate composition . Studies with monovalent antigen-binding fragments of anti-clover root antibody and Azotobacter vinelandii hybrid transformants carrying the unique antigenic determinant suggest that these polysaccharides bind R . trifolii to the clover root hair tips which contain trifoliin.

J Bacteriol, 1979 Feb, 137(2), 825 - 9
Regulation of hydrogenase in Rhizobium japonicum; Maier RJ et al.; Factors that regulate the expression of an H2 uptake system in free-living cultures of Rhizobium japonicum have been investigated . Rapid rates of H2 uptake by R . japonicum were obtained by incubation of cell suspensions in a Mg-phosphate buffer under a gas phase of 86.7% N2, 8.3% H2, 4.2% CO2, and 0.8% O2 . Cultures incubated under conditions comparable with those above, with the exception that Ar replaced H2, showed no hydrogenase activity . When H2 was removed after initiation of hydrogenase derepression, further increase in hydrogenase activity ceased . Nitrogenase activity was not essential for expression of hydrogenase activity . All usable carbon substrates tested repressed hydrogenase formation, but none of them inhibited hydrogenase activity . No effect on hydrogenase formation was observed from the addition of KNO3 or NH4Cl at 10 mM . Oxygen repressed hydrogenase formation, but did not inhibit activity of the enzyme in whole cells . The addition of rifampin or chloramphenicol to derepressed cultures resulted in inhibition of enzyme formation similar to that observed by O2 repression . The removal of CO2 during derepression caused a decrease in the rate of hydrogenase formation . No direct effect of CO2 on hydrogenase activity was observed.

J Bacteriol, 1979 Jan, 137(1), 415 - 9
alpha-Ketoglutarate dehydrogenase mutant of Rhizobium meliloti; Duncan MJ et al.; A mutant of Rhizobium meliloti selected as unable to grow on L-arabinose also failed to grow on acetate or pyruvate . It grew, but slower than the parental strain, on many other carbon sources . Assay showed it to lack alpha-ketoglutarate dehydrogenase (kgd) activity, and revertants of normal growth phenotype contained the activity again . Other enzymes of the tricarboxylic acid cycle and of the glyoxylate cycle were present in both mutant and parent strains . Enzymes of pyruvate metabolism were also assayed . L-Arabinose degradation in R . meliloti was found to differ from the known pathway in R . japonicum, since the former strain lacked 2-keto-o-deoxy-L-arabonate aldolase but contained alpha-ketoglutarate semialdehyde dehydrogenase; thus, it is likely that R . meliloti has the L-arabinose pathway leading to alpha-ketoglutarate rather than the one to glycolaldehyde and pyruvate . This finding accounts for the L-arabinose negativity of the mutant . Resting cells of the mutant were able to metabolize the three substrates which did not allow growth.

J Bacteriol, 1979 Jan, 137(1), 409 - 14
Phosphoglucose isomerase mutant of Rhizobium meliloti; Arias A et al.; A mutant strain of complex phenotype was selected in Rhizobium meliloti after nitrosoguanidine mutagenesis . It failed to grow on mannitol, sorbitol, fructose, mannose, ribose, arabitol, or xylose, but grew on glucose, maltose, gluconate, L-arabinose, and many other carbohydrates . Assay showed the enzyme lesion to be in phosphoglucose isomerase (pgi), and revertants, which were of normal growth phenotype, contained the enzyme again . Nonpermissive substrates such as fructose and xylose prevented growth on permissive ones such as L-arabinose, and in such situations there was high accumulation of fructose 6-phosphate . The mutant strain had about 20% as much exopolysaccharide as the parent . Nitrogen fixation by whole plants was low and delayed when the mutant strain was the inoculant.

Zentralbl Bakteriol Naturwiss, 1979, 134(8), 666 - 71
Studies on nodulation of soyabean in Egypt . I . Selection of an efficient strain of Rhizobium japonicum; Abdel-Nasser M et al.; Both pot (sterilized sand cultures) and field experiments were run, using 23 different strains of Rhizobium japonicum and the commercial soyabean inoculum "Okadin" . The failure of the control (non-inoculated plants) to form nodules may be due to the abscence of adequate densities of effective soyabean-rhizobia strains and their low persistence under Egyptian soil conditions . Therefore, inoculation with an efficient strain of R . japonicum seemed to be necessary . However, the strains used varied in their effectiveness, indicating that both the total number of nodules and total nitrogen content of the nodules should not be taken as an index.

Antonie Van Leeuwenhoek, 1979, 45(2), 165 - 75
Surface carbohydrates of Rhizobium . I . Beta-1, 2-glucans; Zevenhuizen LP et al.; Because of increased interest in surface carbohydrates of Rhizobium in relation to host specificity, phenol-water extractions were carried out of whole cells of Rhizobium strains of the species R . leguminosarum, R . phaseoli, R . trifolii and R . meliloti . Fractionation of the crude extracts with cetavlon afforded polysaccharide mixtures, which were essentially free of RNA and acidic exopolysaccharide (EPS) . They could be separated into a high molecular weight heteropolysaccharide fraction of lipopolysaccharide (LPS) nature and a low molecular weight glucan fraction . Glucan turned out to be the principal polysaccharide component of the cells (up to 10% of the dry cell weight), when cultivated in carbohydrate-rich media, and to be present as firmly attached capsular material . Glucan (mol wt 3000) structure was elucidated by methylation and periodate oxidation techniques . Methylation yielded 3, 4, 6-tri-O-methyl-D-glucose, characterized by GLC-MS, as the only product of hydrolysis of the fully methylated glucan . The glucan consumed 1 mole of periodate per mole anhydroglucose unit and gave sophorose on partial hydrolysis . From these data a linear beta-1,2-linked glucan structure was deduced . The occurrence of beta-1,2-glucan and the implications for the specific binding properties of Rhizobium cells are discussed.

Zentralbl Bakteriol Naturwiss, 1979, 134(7), 600 - 3
Studies on nodulation of soyabeans in Egypt . II . Effect of seed-diffusates on Rhizobium japonicum; Abdel-Nasser M et al.; The growth inhibition zones of R . japonicum (E 45) by either surface-sterilized seeds or autoclaved seeds (as well as dicotyledones, cotyledone, or seed coat) of Harosoy soyabean cultivar indicate the presence of antibacterial substances . Several physical and chemical seed treatments were done in a trial to eliminate or decrease the observed inhibitive effects of the seed-diffusates in order to obtain successful nodulation . The antibacterial substances are thermostable (121 degrees C), water-soluble or partially insoluble, exist in the whole seed and could be inactivated by certain chemical seed treatments as well as by germination for 12 hrs . or more before inoculation.

Folia Microbiol (Praha), 1979, 24(6), 501 - 2
Vesicular-arbuscular mycorrhiza and nodulation in soybean; Varma AK; Dual infections of Glycine max with VA endophytes and Rhizobium, compared with Rhizobium alone, increased the number and weight of nodules significantly in natural field soil and obviated the need of phosphate application for successful nodulation.

Z Allg Mikrobiol, 1979, 19(10), 681 - 5
Salt tolerance of Rhizobium species in broth cultures; Abdel Wahab AM et al.; Salt tolerance of five rhizobia strains was examined in broth cultures . Five levels of NaCl concentration were used and the optical density was taken as a measure for the vigour of bacterial growth . Rhizobium leguminosarum and R . meliloti were tolerant to high levels of salinity and growth curves in saline broth showed a similar pattern to the control level . Rhizobium japonicum, cowpea Rhizobium, and R . trifolii were intolerant to salt and showed a strong growth retardation with increasing salt concentration . Growth was inhibited at high levels of salinity . It is suggested that rhizobia sensitivity to salts may be partly responsible to the inhibition of nitrogen fixation by legumes growing under salt stress.

Can J Microbiol, 1979 Jan, 25(1), 68 - 74
Fatty acid composition of Rhizobium spp; MacKenzie SL et al.; The fatty acid composition of 42 isolates belonging to the major plant affinity groups of Rhizobium has been determined and found to vary reproducible with culture age . Numerical taxonomic techniques applied to the 15 major fatty acid components of log-phase cultures of comparable physiological age showed that the rhizobia constitute a uniform group . However, two clusters comprising soybean-cowpea isolates and pea-bean isolates were evident . These observations, based on a simple analysis of only one group of chemical components, indicate relationships among rhizobia which differ from the conventional plant-affinity groupings but which are consistent with other proposed relationships established using a variety of biochemical and physiological criteria.

Microbios, 1979, 24(97-98), 159 - 71
Environmental factors influencing nitrate respiration in Escherichia coli K12 and Rhizobium trifolii; Skotnicki ML et al.; The nitrate respiratory systems of both the facultative anaerobe Escherichia coli K12 strain W3350 and the aerobe Rhizobium trifolii strain T1 are regulated in a similar manner by a complex set of interactions involving H2, N2, CO2, glucose and nitrate . In addition, the nitrate respiratory system of strain T1 can be regulated by chlorate . A possible mechanism is presented to illustrate how these complex interactions might take place.

Antonie Van Leeuwenhoek, 1979, 45(3), 401 - 15
Growth yields, polysaccharide production and energy conservation in chemostat cultures of Rhizobium trifolii; de Hollander JA et al.; Rhizobium trifolii was grown in a defined medium in chemostat cultures . Extracellular polysaccharide production was found in carbon-sufficient as well as in carbon-limited cultures . Extracellular polysaccharide production in carbon-limited cultures was strongly dependent on the growth rate . In mannitol-limited cultures, asparagine was always totally depleted from the culture medium . Only when the asparagine supply was not sufficient to meet the nitrogen need of the culture, ammonia assimilation took place . Excess organic nitrogen was excreted as ammonia . Whether ammonia assimilation or ammonia excretion took place was also dependent on the growth rate . Respiration-coupled proton translocation measurements showed the presence of three energy conserving sites in an electron transport chain which is branched . Assuming a H+/P ratio of 4, a P/O ratio of 2.33 was found . Growth yield calculations indicated a P/O ratio of approximately 2 . Sulphate limitation in the chemostat culture resulted in a decrease in the efficiency of oxidative phosphorylation and in a less stringent coupling between growth and energy yielding processes.

Zentralbl Bakteriol Naturwiss, 1979, 134(4), 301 - 9
Re-examination of transformation within different species of Rhizobium; Al-Ani FY; Investigations of the phenomenon of transformation in Rhizobium were carried out . Streptomycin resistance (str) was the genetic marker used in all experiments, with the exception of auxotrophic strains . Twenty-one experiments were performed on nine different Rhizobium strains . Some of these strains were previously reported to be transformed, while others had no prior history of transformation . Different conditions which are thought to affect the development of competence were used . In these experiments no positive results were obtained . The possibility that the experiments failed, due to inactivation of donor DNA during its preparation, was ruled out by comparison with results obtained with strains of Bacillus subtilis.

Microbios, 1979, 24(95), 19 - 28
Some antigenic properties of cultured cell and bacteroid forms of fast- and slow-growing strains of Lotus rhizobia; Pankhurst CE; Immunodiffusion cross-reactions of 62 fast- and 76 slow-growing of Lotus rhizobia with antisera to four of the fast-growing and five of the slow-growing strains were studied . No sharing of antigens by both fast- and slow-growing strains was found . Somatic antigens were very strain specific with only eight of the fast-growing and five of the slow-growing strains tested having somatic antigens identical to those of one or more of the strains of the same group used for antisera production . In contrast, internal antigens were shared by all fast-growing strains and with seven exceptions by all slow-growing strains . Antigens of cultured rhizobia, and bacteroids from nodules formed on different legumes by the same strain of Rhizobium, were similar . However, incontrast to cultured cells, bacteroids generally required no pretreatment (heat or ultrasonic disruption) to give a strong somatic antigen reaction in immunodiffusions.

Acta Microbiol Pol, 1979, 28(4), 319 - 24
Occurrence and distribution of rhizobiophages in Indian soils; Dhar B et al.; Soil samples from 30 fields in neighbouring districts of Varanasi were screened for rhizobiophages on 60 Rhizobium strains . Plaques were observed on five strains: P1, P5, SU391 (R . leguminosarum), CB756 and 32H1 (Rhizobium sp.) . Rhizobiophages infective on one or more of the five strains were present in all fields . There seems to be no correlation between presence of phage and the standing crop or the pH (7.1-8.2) of the soil . Eight distinct rhizobiophages have been isolated and characterized for host specificity, plaque morphology and maximum titer in broth.

Acta Microbiol Pol, 1979, 28(3), 221 - 9
Transfer of RP4 and R68.45 factors to Rhizobium; Kowalczuk E et al.; Two R factor were introduced by conjugation into Rhizobium trifolii and Rhizobium meliloti strains at a frequency of 10(-5) to 10(-6) . Plasmids RP4 from Escherichia coli J53 and R68.45 from Pseudomonas aeruginosa PAO.25 were maintained stably in Rhizobium hosts and could be retransferred to other Rhizobium recipients . Some of the transconjugants were able to mobilize chromosome and transfer his or met genes in intra-, and interspecies matings.

Zentralbl Bakteriol Naturwiss, 1979, 134(1), 13 - 8
Strain-specific antigens in Rhizobium leguminosarum; Skrdleta V et al.; Fifty strains of Rhizobium leguminosarum, isolated from five species of host plant (Pisum sativum, P . arvense, Vicia sativa, V . faba, and a Lathyrus sp.) were examined for the presence of strain-specific somatic antigens by immune-diffusions against 13 antisera . Thirty eight strains (76 per cent) were found to belong to the same sero-group and were serologically indistinguishable from each other, but four of these strains also exhibited non-reciprocal cross reactivity with other antisera . In contrast to this, five Australian strains, isolated from P . sativum, showed a high degree of strain specificity.

Acta Microbiol Pol, 1979, 28(1), 47 - 52
The effect of strA mutation on symbiotic nitrogen fixation by Rhizobium meliloti; Zelazna-Kowalska I; Studies on 3H-dihydrostreptomycin accumulation and binding to ribosomes showed that ineffective strain CMts17 carries strB type mutation changing its membrane permeability to the drug . Introduction of high level streptomycin resistance of strA type into strain CMts17 was correlated with acquisition of effectiveness and membrane permeability to the drug . This suggests that changes in membrane permeability, responsible for ineffectiveness of strain CMts17, can be reversed by strA mutation.

Acta Microbiol Pol, 1979, 28(1), 39 - 45
Bacteriocinogeny of Rhizobium trifolii; Zelazna-Kowalska I; Rhizobium trifolii strains differing in cell and colony morphology, streptomycin resistance, phage sensitivity pattern and infectivity to clover plants produced bacteriocins sensitive to proteases . Elimination of bacteriocin production ability wtih SDS and rifampicin treatment indicates that this feature is plasmid controlled . Elimination of bacteriocinogenic plasmid did not influence other features of R . trifolii.

Can J Microbiol, 1978 Dec, 24(12), 1537 - 43
Rhizobium strain identification in Arachis hypogaea nodules by enzyme-linked immunosorbent assay (ELISA); Kishinevsky B et al.; The technique of enzyme-linked immunosorbent assay (ELISA) was used for serological identification of peanut Rhizobium strains both in cell suspension of pure culture and in single root nodules of groundnut (Arachis hypogaea) plants . Antisera of three peanut Rhizobium strains were tested against eight different Rhizobium isolates . Three serogroups identified by agglutination and immunodiffusion tests were confirmed by ELISA . In this experiment ELISA was more sensitive by four to six orders of magnitude than the agglutination and immunodiffusion tests and enabled the detection of Rhizobium antigens in cell suspensions of 10(4)-10(5) cells per millilitre . The reactions of culture and nodule antigens were identical for all strains investigated . ELISA enabled the precise typing of rhizobial isolates in single small root nodules . The minimum fresh weight of nodule tissue necessary to perform the ELISA test was 0.4 mg crushed in 1 ml of phosphate-buffered saline (PBS) . ELISA was also successfully used for strain identification in mixed inoculated plants . One of the strains in each pair formed most of the nodules examined.

Appl Environ Microbiol, 1978 Dec, 36(6), 814 - 8
Nodule infection by bean yellow mosaic virus in Phaseolus vulgaris; Orellana RG et al.; Infection of root nodules of beans, Phaseolus vulgaris L., by bean yellow mosaic virus (BYMV) and the effect of the disease on the specific activity of the nodule are reported . Infectivity and serological microprecipitin assays with two sources of BYMV antiserum demonstrated that nodules from bean plants whose leaves had been inoculated with BYMV contain BYMV antigen . The disease reduced the fresh weights of tops, roots, and root nodules and induced premature nodule decay and/or nodule drop . The disease also reduced leghemoglobin content, on a plant weight basis, and N2 fixation rate, on an individual plant basis, as measured by the acetylene reduction assay . The increased leghemoglobin content per gram-nodule in BYMV-infected nodules relative to healthy nodules might be associated with multiplication of the virus in the nodule and/or unknown cellular effects derived from the BYMV-Rhizobium interaction.

Appl Environ Microbiol, 1978 Dec, 36(6), 915 - 9
Genetically marked Rhizobium identifiable as inoculum strain in nodules of soybean plants grown in fields populated with Rhizobium japonicum; Kuykendall LD et al.; The fate of an inoculum strain of Rhizobium japonicum was studied using a genetically marked strain I-11O subline carrying resistance markers for azide, rifampin, and streptomycin (I-110 ARS) . At the time of planting into a field populated with R . japonicum, seeds of soybean cultivars Kent and Peking were inoculated with varying cell densities of strain I-110 ARS . At various times during the growing season, surface-sterilized root nodules were examined for the presence of the inoculum strain by plating onto selective media . The recovery of the inoculum strain was unambiguous, varying, in the case of Kent cultivar, from about 5% with plants (sampled at 51 days) that had been inoculated with 3 X 10(8) cells per cm of row to about 20% with plants (sampled at 90 days) that had been inoculated with 3 X 10(9) cells per cm . The symbiotically incompatible interaction of Peking and strain 110 in Rhizobium-populated field soil was confirmed by the finding that at 60 days after planting, only one nodule in 360 sampled contained strain I-110 ARS . The use of genetically marked Rhizobium bacteria was found to provide for precise identification of the inoculum strain in nodules of field-grown soybeans.

J Bacteriol, 1978 Dec, 136(3), 1197 - 200
Catabolite-repression-like phenomenon in Rhizobium meliloti; Ucker DS et al.; We report a phenomenon similar to catabolite repression in Rhizobium meliloti . Succinate, which allows the highest observed rate of growth of R . meliloti, caused an immediate reduction of beta-galactosidase activity when added to cells growing in lactose . A Lac- mutant was unaltered in nodulation and nitrogen fixation capacities, but a pleiotropic mutant deficient in several catabolic properties was unable to produce effective nitrogen-fixing nodules.

Nucleic Acids Res, 1978 Nov, 5(11), 4141 - 55
Preparation of a complementary DNA for leghaemoglobin and direct demonstration that leghaemoglobin is encoded by the soybean genome; Baulcombe D et al.; In soybean root nodules, leghaemoglobin (Lb) accounts for 25--30% of the total soluble protein but is not detected in other tissues . In order to determine whether the Lb genes are plant or bacterial in origin a cDNA probe for Lb was prepared from 9S poly (A) containing mRNA of root nodules . Although this 9S mRNA directed synthesis of predominantly three forms of Lb in vitro, the kinetics of hybridisation of cDNA and the 9S mRNA showed a transition at about 30% hybridisation which suggested that the 9S-cDNA was not pure Lb-cDNA . The abundant, Lb-cDNA was prepared by two cycles of hybridising 9S mRNA and cDNA to a Rot of 3 X 10(-3) and isolation of the hybridised cDNA on hydroxyapatite . The Lb-cDNA was homogeneous in hybridisation analysis with 9S mRNA and electrophoresis in 98% formamide gels . This cDNA hybridised with soybean DNA and not with Rhizobium DNA, thus directly demonstrating that Lb genes are of plant origin . Titration of Lb-cDNA with soybean DNA showed that Lb genes are reiterated about forty-fold per haploid genome.

Z Naturforsch {C}, 1978 Nov-Dec, 33(11-12), 859 - 62
Differentiation of Rhizobium japonicum, III . Inhibition of nitrogenase derepression by chloramphenicol and rifampicin concentrations, not inhibiting growth; Werner D; Development of nitrogenase (40--140 nmol C2H4.mg protein-1.h-1) in Rhizobium japonicum 61-A-101 after transfer to special culture conditions (medium 20 P, 2% O2, 10% CO2, 88% N2 in the gas phase) is inhibited by chloramphenicol (6 X 10(-4)--10(-3) M) and by rifampicin (10(-5) M) . These concentrations do not inhibit the slow growth of the cells under these conditions with a doubling time of the cell protein and living cell number of 3--5 d . Nitrogenase activity of previously derepressed cells is not inhibited by chloramphenicol . Growth of the cells under air in yeast extract-mannitol-glycerol medium (8 h doubling time) is affected significantly more by chloramphenicol (2.5 X 10(-4) M) than growth under nitrogenase derepressed culture conditions.

Mol Gen Genet, 1978 Oct 24, 165(3), 323 - 30
Tryptophan genes in Rhizobium--their organization and their transfer to other bacterial genera; Johnston AW et al.; R . leguminosarum trp alleles mapped by R68.45-mediated recombination were located in three distinct chromosomal regions . We isolated three derivatives of R68.45 that carried different trp genes of R . meliloti . Each of the plasmids suppressed all of the R . leguminosarum trp alleles in a particular region . The R-primes were transferred to strains of P . aeruginosa carrying mutations in different trp genes . The plasmid pAJ24JI suppressed trpA, B and F mutants, pAJ73JI suppressed trpC and D and pAJ88JI suppressed a trpE mutant . When the R-primes were transferred to E . coli trp strains they failed to suppress any trp mutants . A derivative of pAJ24JI was isolated which was able to suppress trpA and F mutants of E . coli.

Arch Microbiol, 1978 Oct 4, 119(1), 71 - 4
Carotenoids of rhizobia . II . The effect of nicotine on the carotenoid pattern of Rhizobium lupini; Kleinig H et al.; With increasing concentrations in the growth medium of the cyclization inhibitors nicotine or 2-(4-chlorophenylthio)-triethylamine hydrochloride (CPTA) the previously identified bicyclic carotenoids of Rhizobium lupini (2,3,2',3'-tetrahydroxy-beta,beta-caroten-4-one and 2,3,2',3'-tetrahydroxy-beta,beta-carotene) were successively replaced by hitherto unknown monocyclic carotenoids . By application of mass and nuclear magnetic resonance spectroscopy 3 carotenoids were identified as 2,3-trans-dihydroxy-beta,psi-caroten-4-one, 2,3-trans-dihydroxy-beta,psi-carotene, and 3-hydroxy-beta,psi-caroten-4-one . A further compound was tentatively established as (2- or 3-)monohydroxy-beta,psi-carotene . It was found that other inhibitors such as diphenylamine or 4-chloro-5-(dimethylamino)-2-alpha,alpha,alpha(trifluoro-m-tolyl)-3-(2H)-pyridazinone (San 6706) did not affect the pigment pattern . The results are discussed in relation to carotenoid biosynthesis in Rhizobium lupini.

Can J Microbiol, 1978 Oct, 24(10), 1283 - 7
Studies on bacteroid size and nucleic acid content of alfalfa bacteroids fractionated by velocity sedimentation; Paau AS et al.; A velocity sedimentation procedure was described to fractionate bacteroids of alfalfa nodules into four subpopulations . Bacteroids in these subpopulations were different in size and nucleic acid content as determined by microscopy and flow-microfluorometry (FMF) . The slowest-sedimenting bacteroids (fraction I) were small and resembled free-living Rhizobium meliloti both in size and nucleic acid content . The fastest-sedimenting bacteroids (fraction IV) were 2 to 3 times longer and contained 3 to 4 times more nucleic acid than the small bacteroids in fraction I and free-living R . meliloti . A positive correlation was established between bacteroid size and relative nucleic acid content of bacteroids in alfalfa nodules.

Biol Bull Acad Sci USSR, 1978 Sep-Oct, 5(5), 628 - 33
Action of metabolites of isolated plant tissues on the nitrogenase activity of Rhizobium vigna and Rhizobium meliloti; Bonartseva GA et al.; The dependence of the nitrogenase activity of Rhizobium meliloti on the strain peculiarities of the cultures, the composition of the media used, and the metabolites of legume tissue cultures was demonstrated by the acetylene method . The nitrogenase activity is significantly higher in R . vigna than in R . meliloti, under the same experimental conditions . Enrichment of the Murashige-Skoog medium with arabinose (25 mM), succinate (25 mM), glutamine (2 mM nitrogen), and yeast extract (0.1%) substantially stimulated the nitrogenase activity of a pure culture of R . vigna . The maximum nitrogenase activity on this medium was noted when metabolites of sweet clover tissue were introduced.

Biol Bull Acad Sci USSR, 1978 Sep-Oct, 5(5), 624 - 8
Adaptability of Rhizobium meliloti in callus tissues of alfalfa roots; Shi'nikova VK et al.; The establishment of associative interrelations between nodule bacteria and cells of a callus culture of alfalfa roots, evaluated according to the criterion of nitrogenase activity, was accompanied by considerable inhibition of the plant cells in the period of maximum infection as well as by the dispersal of actively multiplying nodule bacteria on the surface of the callus cells in the first 7 days after infection . The dynamics of the localization of nodule bacteria on the surface of callus cells was studied by the method of scanning electron microscopy.

Mikrobiologiia, 1978 Sep-Oct, 47(5), 849 - 53
{Nitrogenase activity of Rhizobium meliloti and Rhizobium vigna in a root tisse culture of leguminous and nonleguminous plants}; Bonartseva GA et al.; As was shown using the acetylene technique, the nitrogenase activity of Rhizobium meliloti and Rhizobium vigna increased when they were cultivated with the root tissue cultures of legumes (lucerne, sweetclover) and non-legumes (tobacco, glasswort, carrot), particularly in the case of the former . The maximum activity of nitrogenase was found in R . meliloti . The tissue cultures of legumes had no effect on the growth of Rhizobium whereas the tissues of non-legumes stimulated their biomass accumulation though the activity of nitrogenase in both Rhizobium cultures was low in this case . Therefore, the metabolites of legumes produced a specific action on the nitrogenase of nodule bacteria.

Can J Microbiol, 1978 Sep, 24(9), 1073 - 5
{Identification of actinomycetes with antifungal activity which do not affect Rhizobium meliloti}; Antoun H et al.; Thirteen isolates of actinomycetes that have broad antifungal activity and do not affect two efficient strains of Rhizobium meliloti were identified as: Nocardia autotrophica, Streptomyces antimycoticus, S . anulatus, S . capoamus, S . lydicus, S . murinus, S . roseo-luteus, and S . thermotolerans.

J Bacteriol, 1978 Sep, 135(3), 782 - 9
Stimulation of tetrapyrrole formation in Rhizobium japonicum by restricted aeration; Avissar YJ et al.; Cultures of Rhizobium japonicum were grown with vigorous aeration to stationary phase and were then incubated under restricted aeration for several days . Under these "microaerobic" conditions, cellular heme content increased 10-fold, and visible amounts of porphyrins were released into the culture medium . The two predominant porphyrins produced were identified, on the basis of their spectrophotometric and chromatographic properties, as protoporphyrin and coproporphyrin . The cytochrome complement of microaerobic cells partially resembled that of the symbiotic bacteria in that cytochromes alpha-alpha3 were absent and a CO-binding cytochrome 552 was present . During the period of restricted aeration, at the time that the heme content was increasing, there was a similar 10-fold increase in the activities of the first two enzymes of heme biosynthesis, delta-aminolevulinic acid synthase and delta-aminolevulinic acid dehydrase . However, during the same period, the activity of succinyl thiokinase (an enzyme that is required in large amounts whether or not heme is being produced) increased only twofold . These results suggest that reduced oxygen tension may play a role in inducing heme synthesis necessary for leghemoglobin formation and bacterial differentiation in soybean root nodules.

Mikrobiologiia, 1978 Sep-Oct, 47(5), 961 - 3
{Determination of the nitrogen-fixing activity of Rhizobium japonicum under sterile microvegetative conditions}; Bonartseva GA et al.; The nitrogen fixing activity of Rhizobium japonicum in symbiosis with soya grown in the sterile microvegetative conditions at an air humidity of 70%, at a temperature of 20 degrees C and a length of light day of 16 hours was assayed using the acetylene technique . The plants were cultivated in phytotron in glass tubes (245 cm3) illuminated with xenon lamps . This technique can be used, apparently, to determine the nitrogen fixing activity of other legumes and cereals.

J Cell Biol, 1978 Sep, 78(3), 919 - 36
Isolation and characterization of the membrane envelope enclosing the bacteroids in soybean root nodules; Verma DP et al.; The membrane envelope enclosing the bacteroids in soybean root nodules is shown by ultrastructural and biochemical studies to be derived from, and to retain the characteristics of, the host cell plasma membrane . During the early stages of the infection process, which occurs through an invagination, Rhizobium becomes surrounded by the host cell wall and plasma membrane, forming the infection thread . The cell wall of the infection thread is degraded by cellulolytic enzyme(s), leaving behind the enclosed plasma membrane, the membrane envelope . Cellulase activity in young nodules increases two- to threefold as compared to uninfected roots, and this activity is localized in the cell wall matrix of the infection threads . Membrane envelopes were isolated by first preparing bacteroids enclosed in the envelopes on a discontinuous sucrose gradient followed by passage through a hypodermic needle, which released the bacteroids from the membranes . This membrane then sedimented at the interface of 34--45% sucrose (mean density of 1.14 g/cm3) . Membranes were characterized by phosphotungstic acid (PTA)-chromic acid staining . ATPase activity, and localization, sensitivity to nonionic detergent Nonidet P-40 (NP-40) and sodium dodecyl sulfate (SDS) gel electrophoresis . These analyses revealed a close similarity between plasma membrane and the membrane envelope . Incorporation of radioactive amino acids into the membrane envelope proteins was sensitive to cycloheximide, suggesting that the biosynthesis of these proteins is primarily under host-cell control . No immunoreactive material to leghemoglobin antibodies was found inside or associated with the isolated bacteroids enclosed in the membrane envelope, and its location is confined to the host cell cytoplasmic matrix.

Can J Microbiol, 1978 Aug, 24(8), 960 - 6
{Demonstration of extrachromosomal DNA in Rhizobium meliloti}; Bechet M et al.; Seven effective (nitrogen-fixing) strains of Rhizobium meliloti have been studied . By sedimentation analysis of their alkaline lysates in alkaline sucrose gradients, a plasmid was found in four strains . In a strain (2011 str 3) which gave no result with this method, supercoiled DNA was detected by CsCl-dye buoyant density gradient centrifugation . That result was confirmed by analytical Cs2SO4-Ag+ density gradients, which showed a heterogeneity in the average base composition of the DNA extracted from three strains, including the 2011 str 3 strain . Two of those last strains seemed to contain an extrachromosomal DNA of very high molecular weight.

Biochim Biophys Acta, 1978 Jul 21, 535(1), 110 - 24
Purification and biochemical properties of complex flagella isolated from Rhizobium lupini H13-3; Maruyama M et al.; 1 . The complex flagella of Rhizobium lupini H13-3 differ from plain bacterial flagella in the fine structure of their filaments dominated by conspicuous helical bands, in their fragility and their resistance against heat decomposition . To elucidate the basis of these differences, the composition of complex filaments and their subunits was analysed . 2 . Isolated complex flagella containing the filament and hook protions were purified by differential centrifugation . Hooks were separated by ultracentrifugation after acid degradation of filaments at pH 2 . The complex filaments consist of 43 000 dalton monomers (cx-flagellin), the hooks are composed of 41 000 dalton subunits . 3 . Amino acid analysis of cx-flagellin indicated the presence of approx . 417 amino acid residues . These comprise 47% hydrophobic residues and 21% Asp and Glu (or amides), but no Cys, His, Pro and Trp . No carbohydrate, phosphate or lipid moieties have been detected . Fingerprint analysis after tryptic digestion yields approx . 36 peptides, about half of them clustered in the neutral region . A comparison with the composition of varous known flagellins from plain flagella indicates a 7% higher content of hydrophobic amino acid residues in complex filaments; this is largely compensated for by the higher content of Glu and Asp (presumably as Gln and Asn) in plain filaments . 4 . Immunodiffusion and immunoelectrophoresis of cx-flagellin yield single precipitin bands indicating homogeneity . In contrast, isoelectric focusing lead to three close-running bands around pH4.7 . When isolated, the two major bands again produced an "isoelectric spectrum" suggesting that it reflects an allomorphism of cx-flagellin . 5 . Self-assembly experiments with cx-flagellin lead to coiled fibres including helical regions, but not to intact filaments . The products resemble heat-denatured complex filaments and may represent intermediates between monomers and complete polymers.

Can J Microbiol, 1978 Jul, 24(7), 785 - 93
Role of lectins in plant--microorganism interactions . IV . Ultrastructural localization of soybean lectin binding sites of Rhizobium japonicum; Calvert HE et al.; The binding of purified, ferritin-labeled soybean seed lectin to the cell surfaces of Rhizobium japonicum 31 lb 138 has been examined by whole mount, thin section, and freeze-etch electron microscopy . The ferritin-labeled lectin binds in a biochemically specific manner to the capsular material of this bacterium . The lectin does not bind to the outer membranes of the cells or to flagella . Labeled lectin binds to sites throughout the capsular structure, although the density of labeling is somewhat greater on the outer surface of the capsule . Some cells appear to be partially encapsulated . Preservation of the capsular material proved difficult, and methods for retaining most of the capsular material were developed.

Mikrobiologiia, 1978 Jul-Aug, 47(4), 728 - 32
{Ethylmethane sulfonate induction of auxotrophic mutants of Rhizobium meliloti and their characteristics}; Fedorov SN et al.; Ethylmethanesulfonate was used as a mutagen to induce auxotrophic mutants in Rhizobium meliloti L5-30 . Survival of the culture depended on the period of time during which it was treated with the mutagen . Thirteen auxotrophic mutants were isolated as a result of screening 1404 clones, and their requirements in growtn factors were determined . Ethylmethanesulfonate induced mainly those mutants which required sulfur-containing amino acids . The activity of nitrogen fixation of the auxotrophic mutants was assayed by measuring the reduction of acetylene and the yield of lucerne . Mutants requiring methionine or cystein, cysteine or histidine, and adenine with thiamine were not effective whereas those requiring arginine, tryptophan, and thiamine were capable of nitrogen fixation . Among two methionine auxotrophs, one displayed the activity of nitrogen fixation and the other did not.

Immunology, 1978 Jul, 35(1), 105 - 13
Homologous and cross-reactive precipitins in anti-pneumococcal sera raised in mules; Allen PZ et al.; Serial bleedings were obtained from two mules during prolonged immunization, one with type XXV the other with type VIII pneumococcal vaccine . IgGa, IgGb, IgGc, IgB, IgG(T) and IgM present among purified Pn anti-XXV and Pn anti-VIII immunoglobulin isolated from various bleedings were identified by use of rabbit anti-equine heavy chain specific reagents . Radioimmunodiffusion with 14C-labelled type XXV pneumococcal capsular polysaccharide and horse and donkey reagents with species specificity directed against donkey or horse IgGa respectively, demonstrated both parental horse and donkey IgGa heavy chain isotypes among the anti-PnXXV antibodies of the interspecies hybrid . Qualtitative and quantitative examination of the cross-precipitation of mule anti-PnXXV sera with the capsular polysaccharides of pneumococcal types IV, X and XA, with birch sap, ketha gum, and with polysaccharides of E . coli, Klebsiella and Rhizobium was carried out and compared with data obtained with anti-PnXXV raised in a horse . Analysis of supernatants from the cross-reactions showed that distinct subfractions had reacted . indicating a marked heterogeneity of the antibodies.

J Bacteriol, 1978 Jul, 135(1), 114 - 23
Control of ammonium assimilation in Rhizobium 32H1; Ludwig RA; The symbiotic, nitrogen-fixing bacterium Rhizobium sp . 32H1 is a specialized ammonium producer during symbiosis . However, during free-living growth, Rhizobium 32H1 assimilates ammonium very poorly . Two pathways of ammonium assimilation exist in enteric bacteria . One is mediated by glutamate dehydrogenase, and the other is mediated by glutamine synthetase-glutamate synthase . The former pathway is altogether inoperative in Rhizobium 32H1; the latter pathway operates at a slow rate and is under strict negative control by ammonium itself . Rhizobium 32H1 glutamine synthetase activity is modulated by both repression-derepression and reversible adenylylation . For a biochemical process lacking an alternative pathway, such a regulatory pattern exacerbates the very process . This suggests that Rhizobium 32H1 restricts its own ammonium assimilation to maximize the contribution of fixed nitrogen to the host plant during symbiosis.

Mol Gen Genet, 1978 Jun 14, 162(2), 163 - 71
Fertility inhibition in Rhizobium lupini by the resistance plasmid RP4; Puhler A et al.; R plasmid RP4 inhibits the fertility of R . lupini . An RP4 carrying R . lupini donor strain is no longer capable of transferring chromosomal genes . After loss of RP4 the R . lupini fertility reappears . Plasmid RP4 spontaneously mutates at high frequency in R . lupini . RP4 mutants which do not inbibit fertility were isolated . These mutants were always transfer-defective, too . It is postulated that the genetic information for fertility inhibition in R . lupini is a substantial part of the transfer unit of the RP4 plasmid.

Eur J Biochem, 1978 Jun 1, 87(1), 147 - 53
Involvement of the cytoplasmic membrane in nitrogen fixation by Rhizobium leguminosarum bacteroids; Laane C et al.; 1 . The nitrogen-fixing efficiency of freshly prepared suspensions of Rhizobium leguminosarum bacteroids from pea root nodules was considerably enhanced by addition of bovine serum albumin . Evidence was found that during preparation of bacteroids the cell membrane is exposed to the uncoupling effect of free fatty acids and to plant phospholipase D activity . Both effects could be counteracted by bovine serum albumin . 2 . A technique was developed by which concentrations of free O2 and nitrogenase activity could be measured simultaneously under conditions of steady-state respiration . By means of this system it could be shown that in contrast to previous claims, high ATP/ADP ratios can be achieved in bacteroids even with a high concentration of O2 in the medium . 3 . Nitrogen fixation was found to be controlled by the ATP/ADP ratio, the generation of reducing equivalents and the switch-off phenomenon . It was demonstrated that the generation of reducing equivalents for nitrogenase is regulated by the energized state and the integrity of the bacteroid cell membrane . The data indicate that the process of aerobic nitrogen fixation in R . leguminosarum bacteroids resembles that of Azotobacter vinelandii.

Can J Microbiol, 1978 Jun, 24(6), 685 - 8
Interaction between Rhizobium japonicum phage M-1 and its receptor; Dandekar AM et al.; The receptor for phage M-1 was present in the exopolysaccharide (EPS) of Rhizobium japonicum D211 . The EPS was a heteropolysaccharide consisting of glucose, galactose, glucuronic acid, and glucosamine units . These monosaccharides prevented phage-cell attachment indicating that they may mimick the receptor . Phage-cell attachment was either stimulated or inhibited by Mg2+ and Ca2+ depending upon their concentration . An enzyme which depolymerized the exopolysaccharide releasing oligosaccharides was detected in the phage-infected cell lysates . A comparison of the properties of adsorption and those of the depolymerase enzyme indicated that the latter was a component of the phage and appeared to be involved in the phage-receptor interaction.

J Bacteriol, 1978 Jun, 134(3), 1199 - 201
Transfer from Rhizobium japonicum to Azotobacter vinelandii of genes required for nodulation; Maier RJ et al.; A mutant strain of Azotobacter vinelandii that is unable to fix N2 (Nif-) was transformed to Nif+ with DNA from Rhizobium japonicum . Of 50 Nif+ transformants tested, 3 contained the O antigen-related polysaccharide that is present on the cell surface of a nodulating R . japonicum strain, but is absent from a non-nodulating mutant strain.

Biol Bull Acad Sci USSR, 1978 May-Jun, 5(3), 288 - 92
Quantitative cytochemistry of glycogen in cells of pea and lupine nodule bacteria; Shil'nikova VK et al.; Using a fluorescent variation of the method of PAS reaction with auramine OO-SO2, the content of PAS-positive substance, identified on the basis of supplementary treatments of the preparations with alpha-amylase and a hot mixture of chloroform with methanol and glycogen, was determined cytofluorimetrically in cells of effective and ineffective strains of lupine and pea nodule bacteria in pure culture and under conditions of symbiosis . The largest level of glycogen was detected in bacteroid forms from lupine nodules and especially those of the pea after inoculation with ineffective strains: in comparison with the bacteroids from nodules of effective bean-Rhizobium symbiosis, it was 2.5--3.0 times as high . Cytofluorimetric determination of glycogen in cells of nodule bacteria, especially under conditions of symbiosis, can be considered as an indirect criterion of effectiveness in the preliminary selection of strains.

Biol Bull Acad Sci USSR, 1978 May-Jun, 5(3), 281 - 8
Ability of free-living nodule bacteria to fix atmospheric nitrogen; Demina NS; Literature material is presented on the ability of free-living nodule bacteria for asymbiotic nitrogen fixation, detected for the first time in 1975 . Necessary components of the nutrient medium in the use of which the nitrogen-fixing ability of rhizobia in pure cultures is manifested, proved to be sugars and intermediates of the citric acid cycle, as well as small quantities of bound nitrogen . The experimental data available in the literature are evidence of the presence of a complete assortment of genes for the synthesis of the nitrogenase enzyme complex in free-living nodule bacteria.

Can J Microbiol, 1978 May, 24(5), 558 - 62
{Actinomycetes antagonistic to fungi and not affecting Rhizobium meliloti}; Antoun H et al.; The effects of 481 actinomycetes isolated from agricultural soils supporting good growth of alfalfa or clover on two efficient strains of Rhizobium meliloti A2 and S14 were studied . Strain A2 was inhibited by 28% of the isolates and strain S14 was inhibited by 31% of them . No significant difference was found between the resistance of both actinomycete strains . The effects of the 288 isolates not affecting R . meliloti on six fungi were also studied . The most sensitive fungus was Stemphylium sarcinaeforme inhibited by 20% of the isolates, while Fusarium culmorum was the most resistant fungus and was inhibited by only 6% of the isolates . Thirteen isolates inhibited four to six fungi . In an autoclaved greenhouse soil, isolate 181 which inhibited the six fungi tested significantly reduced the population of the phytopathogenic fungus F . oxysporum f . sp . medicaginis and eliminated the inhibitory effect showed by this fungus on strain A2 of R . meliloti.

Can J Microbiol, 1978 May, 24(5), 520 - 4
Effects of interactions between different culture fractions of 'phosphobacteria' and Rhizobium on mycorrhizal infection, growth, and nodulation of Medicago sativa; de Aguilar CA et al.; Interactions between cell-free culture supernatants, cells, and the whole cultures of Rhizobium and phosphobacteria with endomycorrhizal fungi and their effects on growth and nutrition of Medicago sativa grown in a low-phosphate soil were studied . A satisfactory nodulation was greatly dependent on the mycorrhizal symbiosis . Cell-free supernatants of Rhizobium and phosphobacteria improved plant growth, nodulation and mycorrhiza formation . The activity of phosphobacterial culture seemed to be due mainly to the supernatant and the possibility of plant hormones contained in this culture fraction being involved in such interactions is discussed . An increase of the overall pool of soluble P in soil by the inoculated phosphobacteria cells was not found in the conditions of this experiment . It was noteworthy that the best positive effect was achieved by the treatment which consisted of the whole cultures of Rhizobium, phosphobacteria, and the mycorrhizal fungi applied all together.

J Cell Sci, 1978 Apr, 30, 129 - 49
Membranes in lupin root nodules . I . The role of Golgi bodies in the biogenesis of infection threads and peribacteroid membranes; Robertson JG et al.; The process of infection of lupin nodule cells by rhizobia was examined using thin-section and freeze-fracture electron-microscopic techniques to characterize the properties of different membranes and to establish relationships between them . The membranes of the Golgi bodies and the endoplasmic reticulum stained with zinc iodide-osmium tetroxide but not with phosphotungstic acid or silver . By contrast the infection thread membranes, peribacteroid membranes, plasma membranes and membranes of cytoplasmic vesicles did not stain with zinc iodide-osmium tetroxide but stained with phosphotungstic acid and silver . The peribacteroid membranes and plasma membranes are, however, different from each other since the particle density on the E face of freeze-fracture replicas of plasma membranes was twice that on the E face of the peribacteroid membranes . An examination of the tips of the infection threads in the cytoplasm of the plant cells, showed that the rhizobia bud off from the infection threads enclosed in the infection thread membranes . The rhizobia continue to divide still surrounded by membranes of plant origin, namely the peribacteroid membranes . Cytoplasmic vesicles are observed in both thin-section and freeze-fracture preparations of nodule tissue closely associated with, and apparently produced by, Golgi bodies . Formation of the walls and membranes of the infection threads and of the peribacteroid membranes involves fusion of the cytoplasmic vesicles with these membranes . It is proposed that the process of infection of plant cells in lupin nodules involves a change in the function of the Golgi body system for the biogenesis of plant cell walls and plasma membranes to include the synthesis of the walls and membranes of the infection threads and also the peribacteroid membranes.

Biochim Biophys Acta, 1978 Mar 20, 539(3), 276 - 86
Trifolin: a Rhizobium recognition protein from white clover; Dazzo FB et al.; A protein agglutinin, trifoliin, was purified from white clover seeds and seedling roots . Trifoliin specifically agglutinates the symbiont of clover, Rhizobium trifolii, at concentrations as low as 0.2 microgram protein/ml, and binds to the surface of encapsulated R . trifolii 0403 . This clover protein has a subunit with Mr approximately 50 000, an isoelectric point of 7.3, and contains carbohydrate . Antibody to purified trifoliin binds to the root hair region of 24-h-old clover seedlings, but does not bind to alfalfa, birdsfoot trefoil or joint vetch . The highest concentration of trifoliin on a clover root is present at sites where material in the capsule of R . trifolii binds . 2-Deoxy-D-glucose elutes trifoliin from intact clover-seedling roots, suggesting that this protein is anchored to root cell walls through its carbohydrate binding sites . We propose that trifoliin on the root hair surface plays an important role in the recognition of R . trifolii by clover.

Can J Microbiol, 1978 Mar, 24(3), 209 - 14
Transformation of Azotobacter vinelandii strains unable to fix nitrogen with Rhizobium spp . DNA; Page WJ; The phenotypes of Azotobacter vinelandii ATCC 12837 strains defective in nitrogen fixation (Nif-) were characterized by intrageneric transformation with known Nif- strains of A . vinelandii OP . These former mutant strains were used as recipients for intergeneric transformation by deoxyribonucleic acid (DNA) prepared from Rhizobium spp . to determine if the rhizobia would transform the Azotobacter Nif- phenotypes to Nif+ . The frequency of Nif+ transformants using Rhizobium DNA was always less than the frequency using Azotobacter wild-type DNA but was greater than the spontaneous reversion frequency . The Azotobacter Nif+ recombinants also were stable . DNA from all of the Rhizobium spp . transformed to Nif+ Azotobacter mutants defective in the nitrogenase component I (molybdoferredoxin); however, some recombinants had a lower nitrogenase activity and a delayed nitrogenase depression time . Mutants defective in the pleiotrophic transcriptional control of both nitrogenase components were transformed to Nif+ by the asymbiotic nitrogen fixing Rhizobium sp . 32H1 and 41A1, but not the symbiotic nitrogen-fixing species . The significance of these results and the possible future applications of this system are discussed.

Can J Microbiol, 1978 Mar, 24(3), 307 - 11
Hydrogen evolution and uptake by nodules of soybeans inoculated with different strains of Rhizobium japonicum; Carter KR et al.; Hydrogen evolved by nitrogenase may be recycled by a hydrogenase present in some legume nodules . Anoka and Portage cultivars of soybeans were inoculated with each of 8 and 24 strains, respectively, of Rhizobium japonicum and surveyed for H2 evolution and C2H2 reduction rates nodule weight, and plant dry weight . Six of the strains (3Ilb 110, USDA 122, USDA 136, 3Ilb 6, 3Ilb 142, and 3Ilb 143) which exhibited no H2 evolution in air were shown to take up H2 . The relative efficiencies of nitrogenase energy utilization based on C2H2 reduction rates of nodules relative efficiences of nitrogenase energy utilization based on C2H2 reduction rates of nodules ranged from 0.96 to 1.0 for the six strains . Nodules formed by strain WA 5099-1-1 evolved small amounts of H2 in air and had a relative efficiency of 0.92 . Nodules formed by the remaining 25 strains had relative efficiencies ranging from 0.41 to 0.80 . A H2-evolving (3Ilb 123) and non-H2-evolving (3Ilb 143) strain were tested on seven soybean cultivars to determine the effect on the expression of hydrogenase . Nodules formed by strain 3Ilb 143 exhibited an efficiency of 1.0 on the following cultivars: Amsoy 71, Anoka, Bonus, Clark 63, Kent, Peking, and Portage . Relative efficiencies from 0.63 to 0.77 were determined for the five cultivars nodulated by strain 3Ilb 123 . From the experiments with these cultivars, the capacity to recycle H2 produced from the nitrogenase system appears to be determined by the R . japonicum strain.

J Bacteriol, 1978 Mar, 133(3), 1393 - 400
Ultrastructure of Rhizobium japonicum in relation to its attachment to root hairs; Bal AK et al.; In Rhizobium japonicum strain Nitragin 61A76, morphologically distinct types of bacteria were found to occur in yeast extract-mannitol broth cultures, at both mid-log and stationary phases . Of these only the capsular form, characterized by a smooth cell envelope, storage granules (glycogen and poly-beta-hydroxybutyric acid), and an amorphous extracellular capsule, bound soybean lectin . The binding site was localized in the capsular material . Less than 1% of the bacterial population differentiated into these capsular forms, which were also able to attach to the soybean root hair surface.

J Bacteriol, 1978 Mar, 133(3), 1295 - 9
Involvement of Rhizobium japonicum O antigen in soybean nodulation; Maier RJ et al.; Non-nodulating mutant strains of Rhizobium japonicum lacked a surface antigen that was present on the wild type . This surface antigen is associated with the O antigen portion of the lipopolysaccharide . Paper chromatography of hydrolyzed lipopolysaccharide and O antigen revealed three major component differences between the non-nodulating strains and the wild type.

Z Naturforsch {C}, 1978 Mar-Apr, 33(3-4), 245 - 52
Differentiation of Rhizobium japonicum, I . enzymatic comparison of nitrogenase repressed and derepressed free living cells and of bacteroids; Werner D et al.; Derepressed free living cells of Rhizobium japonicum strain 61-A-101 with leucine as single nitrogen source develop a maximum nitrogenase activity of 180 nmol C2H4.mg protein -1.H-1 in liquid culture under 2% 2% O2 in the gas phase . Only 10% of this activity is found with no oxygen in the gas phase during a 90 min incubation period . The maximum activity under 2% oxygen in the gas phase is unaffected by addition of 1-100 mM NH+4 and by addition of low concentrations of glutamine (0.36-1.44 mM) . Specific activities of alanine dehydrogenase (E.C . 1.4.1.1.) asparatate aminotransferase (E.C . 2.6.1.1.) and, with much lower activities, of GOGAT (E.C . 1.4.1.13) in nitrogenase active free living cells are more similar to bacteroids than to nitrogenase repressed free living cells from liquid culture . The activities in nitrogenase repressed cells were about 50% lower . Glutamine synthetase (E.C . 6.3.1.2.) activity in bacteroids and in nitrogenase active cells were also similar, but only about 25-30% of that found in nitrogenase repressed Rhizobium japonicum cells.

Biochim Biophys Acta, 1978 Feb 13, 539(1), 1 - 11
The effect of ammonium nitrate on the synthesis of nitrogenase and the concentration of leghemoglobin in pea root nodules induced by Rhizobium leguminosarum; Bisseling T et al.; The effects of NH4NO3 on the development of root nodules of Pisum sativum after infection with Rhizobium leguminosarum (strain PRE) and on the nitrogenase activity of the bacteroids in the nodule tissue were studied . The addition of NH4NO3 decreased the nitrogenase activity measured on intact nodules . This reduction of nitrogen fixation did not result from a reduced number of bacteroids or a decreased amount of bacteroid proteins per gram of nodule . The synthesis of nitrogenase, measured as the relative amount of incorporation of {35S}sulfate into the components I and II of nitrogenase was similarly not affected . The addition of NH4NO3 decreased the amount of leghemoglobin in the nodules and there was a quantitative correlation between the leghemoglobin content and the nitrogen-fixing capacity of the nodules . The conclusion is that the decrease of nitrogen-fixing capacity is caused by a decrease of the leghemoglobin content of the root nodules and not by repression of the nitrogenase synthesis.

Can J Microbiol, 1978 Feb, 24(2), 143 - 8
Inducing effect of plant cells on nitrogenase activity by Spirillum and Rhizobium in vitro; Child JJ et al.; Eleven different plant cell tissue cultures of both legume and non-legume origin have been grown in direct association, and in separate but close proximal association with both Spirillum lipoferum and Rhizobium sp . 32H1 . Basic similarities were found in the nutritional requirement for the induction of nitrogenase activity (C2H2) in both organisms . In the absence of plant cell cultures both organisms need to be provided with a pentose sugar and a tricarboxylic acid to induce high levels of nitrogen-fixing activity . Plant cell callus tissue appears only capable of supplying the tricarboxylic acid to induce high levels of nitrogen-fixing activity . Plant cell callus tissue appears only capable of supplying the tricarboxylic acids needed but not the sugar component . The plant tissue, however, seems able to activate certain carbohydrates, which in themselves are incapable of substituting for the pentose additive.

Biochim Biophys Acta, 1978 Feb 1, 538(3), 406 - 16
Activity of nitrogenase and glutamine synthetase in relation to availability of oxygen in continuous cultures of a strain of cowpea Rhizobium sp . supplied with excess ammonium; Bergersen FJ et al.; In samples from nitrogen-fixing continuous cultures of strain CB756 of the cowpea type rhizobia (Rhizobium sp.), newly fixed NH+4 is in equiblibrium with the medium, from where it is assimilated by the glutamine synthetase/glutamate synthase pathway . In samples from steady state cultures with different degrees of oxygen-limitation, nitrogenase activity was positively correlated with the biosynthetic of glutamine synthetase in cell free extracts . Also, activities in biosynthetic assays were positively correlated with activities in gamma-glutamyl transferase assays containing 60 mM Mg2+ . Relative adenylylation of glutamine synthetase was conveniently measured in cell free extracts as the ratio of gamma-glutamyl transferase activities without and with addition of 60 mM Mg2+ . Automatic control of oxygen supply was used to facilitate the study of transitions between steady-state continuous cultures with high and low nitrogenase activities . Adenylylation of glutamine synthetase and repression of nitrogenase activity in the presence of excess NH+4, were masked when oxygen strongly limited culture yield . Partial relief of the limitation in cultures supplied with 10 mM NH+4 produced early decline in nitrogenase activity and increase in relative adenylylation of glutamine synthetase . Decreased oxygen supply produced a rapid decline in relative adenylylation, followed by increased nitrogenase activity, supporting the concept that control of nitrogenase synthesis is modulated by glutamine synthetase adenylylation in these bacteria.

Biochim Biophys Acta, 1978 Jan 18, 538(2), 244 - 8
The role of ammonia, L-glutamate, and cyclic adenosine 3',5'-monophosphate in the regulation of ammonia assimilation in Rhizobium japonicum; Upchurch RG et al.; The effects of three factors (ammonia, L-glutamate, and cyclic adenosine 3',5'-monophosphate) on the ammonia assimilatory processes in aerobically grown Rhizobium japonicum colony derivatives were examined . Ammonia repressed glutamine synthetase activity and increased the average state of adenylylation of this enzyme . The addition of L-glutamate drastically decreased growth and strongly repressed glutamate synthase levels . Glutamine synthetase repression and adenylylation state were also increased by L-glutamate . The presence of cyclic AMP led to the repression of all three NH+4 assimilatory enzymes.

Biochim Biophys Acta, 1978 Jan 12, 522(1), 84 - 9
Purification and characterisation of D-amino acid aminotransferase from Rhizobium japonicum; Gosling JP et al.; Rhizobium japonicum has D-amino acid aminotransferase and alanine racemase activities . The D-amino-acid aminotransferase has been partially purified and characterized . This enzyme has a broad specificity and is very active with D-alpha-aminobutyrate and D-aspartate as well as D-alanine and D-glutamate . The stereospecificity of the enzyme for D-amino acids was apparently absolute with respect to product inhibition, pyridoxamine formation as well as catalytic activity . The apparent molecular weight was 58,000 and the pH optimum was 7.8-7.9 . The equilibrium constant in the direction of D-glutamate formation was 1.9 . Initial-velocity kinetic studies indicate the enzyme acts by a ping-pong mechanism . The dissociation constant for pyridoxal phosphate and the Michaelis constants (+/- standard errors) for D-alanine and 2-oxoglutarate were determined to be 0.51 +/- 0.06 micrometer, and 2.13 +/- 0.18 and 0.058 +/- 0.005 mM respectively . The enzyme is moderately inhibited (30%) by 4 mM p-chloromercuribenzoate.

Microbios, 1978, 22(87), 7 - 13
Quality and rate of extracellular polysaccharides produced by Rhizobium meliloti and their inducing effect on polygalacturonase production in legume roots as derived from the presence of extrachromosomal DNA; Palomares A et al.; The ability of extracellular polysaccharides of different strains of Rhizobium meliloti to induce the production of polygalacturonase by roots of Medicago sativa seedlings has been studied . Some strains showed a high inducing activity while those derived from them, after treatment with acridine orange and in which extrachromosomal DNA was absent, did not show this character . A comparative study of polysaccharide production and preliminary studies on the chemical composition of the active fractions obtained after Sephadex G-25 filtration indicated that the monomers which form the active fractions are qualitatively and quantitatively different according to their origin.

Microbios, 1978, 21(83), 33 - 9
Induction of polygalacturonase production in legume roots as a consequence of extrachromosomal DNA carried by Rhizobium meliloti; Palomares A et al.; The ability of Rhizobium meliloti to induce polygalacturonase production in legume roots decreased during culture under laboratory conditions but was inducible with mitomycin C . This character was irreversibly lost after treatment with acridine orange . Extrachromosomal DNA of molecular weight 5.9 x 10(6) daltons was detectable in neutral sucrose gradient but was absent from cells 'cured' with acridine orange . Therefore, the ability to induce the enzyme production may be controlled by a plasmid.

Zentralbl Bakteriol Naturwiss, 1978, 133(5), 408 - 13
The correlation between the efficiency of rhizobia and nitrate reductase and dehydrogenase activities of cowpea nodules; Tewfik MS et al.; Cowpea seeds variety Fettriat were planted in Nile silt soil and inoculated with 5 strains of cowpea rhizobia . After 50 and 80 days, the plants were uprooted, analysed for dry weight, total nitrogen, fresh weight of nodules, nitrate reductase activity in the leaves, and nitrate reductase and dehydrogenase activities in the nodule homogenate in the presence or absence of succinate, citrate, and ethyl alcohol . The data were analysed to establish the correlation coefficients between total nitrogen and other characteristics . A significant positive correlation existed between total nitrogen and fresh weight of nodules in both cuts (after 50 and 80 days) . The correlation was significant between total nitrogen and dry weight of the plants in the first cut, but was non-significant in the second one . Nitrate reductase activity in leaves and nodule homogenates in the presence of different hydrogen donors were positively correlated in the first cut and negatively correlated in the second one . Nitrate reductase activity in the leaves was much less than that in the nodule homogenates . A negative correlation was noticed between phenol content of the nodules and total nitrogen . In the first cut, while the correlation between total nitrogen and dehydrogenase activity in the presence of citrate or absence of any hydrogen donors was positive, it was negative with ethanol and succinate . In the second cut, however, all the dehydrogenase activities were negatively correlated with total nitrogen.

Zentralbl Bakteriol Naturwiss, 1978, 133(5), 394 - 9
Trifluralin effect on Pisum--Rhizobium relationship; Afifi AF et al.; Trifluralin inhibited root and shoot elongation of Pisum sativum plant and caused isodiametric increase in cell volume of both tissues . The water content of the plant was not affected . The weedicide inhibited also growth and O2 uptake of Rhizobium leguminosarum, isolated from Pisum plant . Reduction in the nitrogen content of Pisum tissues was noticed, and this may be attributed to the inhibition of nodule formation . Variations in the free and protein-amino acids were observed in the plant tissues, due to the application of the weedicide.

Zentralbl Bakteriol Naturwiss, 1978, 133(3), 204 - 10
Survival and efficiency of cowpea rhizobia on pelleted and non-pelleted peanut seeds, treated with fungicides; Hamdi YA et al.; Peanut seeds were either normally inoculated with the legume inoculant Okadin, containing cowpea rhizobia, or pelleted and treated with each of the fungicides Brassical, Thiram, Orthocide 75, Falisan, Vitavax 75, and Agrosan . The seeds were then incubated at room (+/- 25 degrees C) or refrigeration temperatures (+/- 5 degrees C) . Survival tests were made after 2 and 10 days . Treated seeds were also planted in pots containing Nile silt for testing the efficiency of rhizobia as affected by the fungicide and the pelleting treatments . Pelleting of peanut seeds enhanced the survival of rhizobia whether seeds were incubated at room or refrigeration temperature . Protection was more pronounced when seeds were kept at low temperature . This was true of the fungicides Brassical, Orthocide 75, Vitavax 75, Thiram, and Agrosan . Falisan, however, did not help the rhizobia to survive . All the fungicides tested reduced the number of rhizobia to nil within 10 days when the seeds were normally inoculated and then treated and incubated at room temperature . The numbers of rhizobia were appreciably reduced when incubated at refrigeration temperature . Pelleting tended to prevent the harmful effect of the fungicides . This was clearly demonstrated with a tendency of an increase in the total nitrogen of the plants . On the contrary, normally inoculated and treated seeds grew into plants with reduced amounts of total nitrogen fixed.

Biochimie, 1978, 60(3), 237 - 43
Membrane energization in relation with nitrogen fixation in Azotobacter vinelandii and Rhizobium leguminosarum bacteroids; Veeger C et al.; Nitrogen fixation in A . vinelandii and R . leguminosarum bacteroides shows identical characteristics with respect to the dependence on membrane energization, the sensitivity to uncouplers, the ATP/ADP-ratio, and the dependences on flavodoxinhydroquinone as electrondonor . Although we have been successful in preparing inside-out vesicles which can be energized, attempts to couple these membranes to N2-ase were still unsuccessful . One of the major problems could be the failure to energize these vesicles directly by ATP . Although subject to polymerisation after addition of MgCl2, it could be shown that the actual mol.wt . of the O2-stable N2-ase complex is about 300,000 in agreement with a 1:1:1 stoichiometry of the three constituent proteins, namely, component I, component II and the 2Fe-2S protein.

Biochimie, 1978, 60(3), 233 - 6
Nitrogenase--hydrogenase interrelationships in Rhizobia; Dixon RO; A review is given of the properties of the hydrogenase present in Rhizobium bacteriods together with a discussion and evidence of the function of the enzyme in relationship to nitrogen fixation . The efficiency with which nodules fix nitrogen i.e . the amount of hydrogen evolved as a ratio of the total electron flow through nitrogenase, is considered and the recycling of hydrogen is discussed . Attention is drawn to recent work, in which plants which have nodules containing hydrogenase have been shown to fix more nitrogen and increase more in dry matter than plants with nodules without hydrogenase.

Zentralbl Bakteriol Naturwiss, 1978, 133(1), 50 - 3
Influence of light on pectic enzymes in root exudates of Trifolium alexandrinum inoculated with Rhizobium trifolii; Chhonkar PK; An in vitro experiment was conduced under bacteriologically controlled conditions to examine the effect of light on the production of pectin methyl esterase (PME) and pectin polygalacturonase (PG) in the root exudates of Trifolium alexandrinum inoculated with an efficient strain of Rhizobium trifolii . The results revealed that PME and PG increased with an increase in the duration of light to which plants were exposed . However, both the enzymes were detected in the root exudates of nonphotosynthesizing plants.

Appl Environ Microbiol, 1978 Jan, 35(1), 210 - 3
Pectolytic enzymes in Rhizobium; Hubbell DH et al.; A sensitive pectin agar plate assay was used to demonstrate low levels of pectolytic enzymes in infective and noninfective strains of Rhizobium . The possible relation of this characteristic to legume infection is discussed.

Zentralbl Bakteriol Naturwiss, 1978, 133(7-8), 643 - 6
Some aspects of fermentation of Rhizobium leguminosarum with reference to economy of ingredients in the substrate; Gulati SL et al.; Incremental feeding of nutrients was found to be beneficial in mass cultivation of R . leguminosarum . Similarly, semi-continuous fermentation of R . leguminosarum up to 4 days was also found to be useful in maintaining the viable number of cells.

Microbios, 1978, 23(93-94), 167 - 73
Nitrogenase activity of Rhizobium sp . strains in pure culture in relation to extracellular polysaccharide composition and antigenic affinity; Kennedy LD et al.; Five strains of slow-growing Rhizobium sp . (strains CB756, 32HI, CB562, CB627 and QA549) out of seventy examined developed appreciable nitrogenase activity in pure culture . CB756 and 32HI were serologically indistinguishable and each produced 6-deoxy-L-talose as a major component of its extracellular polysaccharide . They did not share these properties with CB562, CB627 or QA549.

Acta Microbiol Pol, 1978, 27(4), 339 - 45
Restoration of effectiveness of R . meliloti ineffective mutants by transduction of high level streptomycin resistance; Zelazna-Kowalska I et al.; Rhizobium meliloti lysine dependent mutant, L5-30lys, was ineffective and this mutation was not cotransducible to lys . Transduction of chloramphenicol and linked temperature sensitive mutations did not change its symbiotic properties . Subsequent transduction of high level streptomycin resistance restored its effectiveness . Streptomycin resistance marker was linked to chloramphenicol resistance and temperature sensitive markers.

Acta Microbiol Pol, 1978, 27(4), 309 - 19
Genetic mapping of the chromosome of Rhizobium trifolii; Zurkowski W et al.; Cultures of the wild strain and auxotrophic mutants of Rhizobium trifolii T37 synchronized by means of phenylethanol have been mutagenized with nitrosoguanidine . Fifteen genetic markers were characterized in respect of their order and the time of replication based on the peaks of mutations of the genes . The time of R . trifolii chromosome replication was estimated using inhibitors of the initiation of DNA replication: rifampicin, chloramphenicol and phenylethanol . The replicative map of R . trifolii chromosome has been constructed . Taking into account the replicative map, linkages of the genes, and the bidirectional model of the Rhizobium chromosome replication, a circular genetic map of the chromosome of R . trifolii T37 was elaborated.

Acta Microbiol Pol, 1978, 27(2), 81 - 8
Genetic transformation in Rhizobium trifolii; Drozanska D et al.; Markers controlling the synthesis of amino acids and organic bases as well as streptomycin resistance and sensitivity to acriflavine were transformed in Rhizobium trifolii . The results indicate that the str marker was transformed independently of leu, his, ade and trp markers . Co-transformation of leu and utra markers ranged from 3 to 7%, whereas that of thi and acr was 10%.

Acta Microbiol Pol, 1978, 27(1), 5 - 9
Nitrogen fixation by Rhizobium in pure cultures; Lorkiewicz Z et al.; Strains of Rhizobium trifolii and Rhizobium meliloti were tested for their asymbiotic nitrogen fixation ability . From among ten tested strains two R . trifolii and one R . meliloti expressed nitrogenase activity within the range of 1.3--9.3 nM C2H4/h/mg protein . Asymbiotic nitrogen fixation was affected by the composition of the medium.

Zentralbl Bakteriol Naturwiss, 1978, 133(7-8), 638 - 42
A comparative study of different factors involved in mass cultivation of rhizobia, using shakers and fermentors; Gulati SL; Growth was proportionally linear to increasing load of inoculum although an inoculum load of 6 to 8% was optimum to obtain uniform number of viable cells, beyond which the number of viable cells did not increase . From the point of view of contamination with other microorganisms and the nodulating ability of cultures, fermentor cultures were better than shake cultures . When growth of Rhizobium was studied in relation to unit of mannitol consumed, it was observed that fermentors are more economical for culturing rhizobia than shakers.

Biochim Biophys Acta, 1977 Dec 22, 500(2), 277 - 90
Regulation of nitrogen fixation in Rhizobium spp . Isolation of mutants of Rhizobium trifolii which induce nitrogenase activity; O'Gara F et al.; This communication describes the isolation and characterization of mutants of Rhizobium trifolii which can induce nitrogenase activity in defined liquid medium . Two procedures were used for the isolation of these mutants from R . trifolii strain DT-6: (1) following chemical mutagenesis, slow growing mutants were selected which were unable to utilize NH+4 as sole source of nitrogen; (2) as spontaneous mutants resistant to the glutamate analogue L-methionine-DL-sulfoximine . Mutants (DT-71, DT-125) isolated by these procedures induced nitrogenase activity in the free-living state, whereas the parent strain lacked this property . Induction of nitrogenase activity in these mutants occurred during the late exponential phase of growth when the rate of protein synthesis was decreasing . The addition of NH+4 to a medium containing glutamate as the nitrogen-source resulted in a 50--70% reduction (repression?) of nitrogenase activity; in contrast, the rate of protein synthesis or the rate of respiration was not influenced by exogenous NH+4 . Biochemical analysis showed that these mutants (strains DT-71 and DT-125) have defects in both nitrogen and carbon metabolism . The levels of glutamate synthase (both NADP+ -and NAD+ -dependent activities) and glutamate dehydrogenase (NAD+-dependent activity) were markedly lower . In addition, the mutants were found to have no detectable ribitol dehydrogenase or beta-galactosidase activity . These findings are discussed in relation to a mechanism of regulation of symbiotic nitrogen fixation.

Science, 1977 Dec 2, 198(4320), 938 - 40
Intergeneric transfer of genes involved in the Rhizobium-legume symbiosis; Bishop PE et al.; Genes that seem to be involved in the initial steps of infection of a legume by Rhizobium have been transferred, by transformation, to mutant strains of Azotobacter vinelandii that are unable to fix nitrogen . These genes code for a surface antigen that binds specifically to a protein from the host plant.

Appl Environ Microbiol, 1977 Dec, 34(6), 854 - 6
Viability of Rhizobium bacteroids; Tsien HC et al.; Bacteroids prepared from nodules of soybean and bean were tested for viability . Contrary to the prevailing view that bacteroids are nonviable, it was found that bacteroids averaged 90% viability, irrespective of Rhizobium strain, nodule age, or nodule environment.

J Gen Virol, 1977 Nov, 37(2), 337 - 47
Adsorption of a phage tail-like bacteriocin to isolated lipopolysaccharide of Rhizobium; Pfister H et al.; Purified lipopolysaccharide (LPS) from the bacteriocin sensitive strain Rhizobium lupini i6-2 was shown to neutralize the killing activity of the bacteriocin . In the electron microscopical preparation the phage tail-like bacteriocin appears to be adsorbed to the LPS; the tail sheath is contracted and the fibres are oriented towards the LPS ribbon . In contrast, no interaction was observed between the bacteriocin and the LPS of two resistant strains of Rhizobium (16-2/Ii and 16-3) . The inactivation of the bacteriocin by LPS depends on salt concentration, pH, and temperature . The receptor activity of LPS was destroyed by mild acid hydrolysis and by treatment with deoxycholate, which indicates that the micellar structure of the LPS is necessary for bacteriocin adsorption . The chemical composition of the 16-2 LPS was compared to that of the LPS of two resistant strains . In the case of 16-2/ii LPS minor modifications suffice to confer resistance against the bacteriocin.

Arch Microbiol, 1977 Oct 24, 115(1), 103 - 8
Regulation of symbiotic nitrogen fixation in root nodules of alfalfa (Medicago sativa) infected with Rhizobium meliloti; Kamberger W; Symbiotic nitrogen fixation of Rhizobium meliloti bacteroids in Medicago sativa root nodules was suppressed by several inorganic nitrogen sources . Amino acids like glutamine, glutamic acid and aspartic acid, which can serve as sole nitrogen sources for the unnodulated plant did not influence nitrogenase activity of effective nodules, even at high concetrations . Ammonia and nitrate suppressed symbiotic nitrogen fixation in vivo only at concentrations much higher than those needed for suppression of nitrogenase activity in free living nitrogen fixing bacteria . The kinetics of suppression were slow compared with that of free living nitrogen fixing bacteria . On the other hand, nitrite, which acts as a direct inhibitor of nitrogenase, suppressed very quickly and at low concentrations . Glutamic acid and glutamine enhanced the effect of ammonia dramatically, while the suppression by nitrate was enhanced only slightly.

J Bacteriol, 1977 Oct, 132(1), 8 - 12
{3H} dihydrostreptomycin accumulation and binding to ribosomes in Rhizobium mutants with different levels of streptomycin resistance; Zelazna-Kowalska I; Rhizobium trifolii B1, a symbiotic nitrogen fixer, is sensitive to streptomycin (10 microgram/ml) and spontaneously produces spheroplast-like forms during cultivation . Streptomycin-resistant mutants selected with high doses of antibiotic (1,000 microgram/ml) showed pleiotropic changes, including loss of spheroplast formation and infectivity to plants, whereas mutants selected with low doses of streptomycin (10 to 100 microgram/ml) retained properties of parent strain B1 (I . Zelazna-Kowalska, Acta Microbiol . Pol., in press) . The present studies revealed that strain B1 and its mutant with a high level of streptomycin resistance, B1 strH, accumulated the antibiotic at similar rates . Mutant B1 strL, with a low level of streptomycin resistance (up to 100 microgram/ml), accumulated the antibiotic at a lower rate . Ribosomes isolated from strains B1 and B2 strL bound {3H}dihydrostreptomycin, whereas those from strain B1 strH did not . These observations indicate that, in R . trifolii B1, mutation to a high level of streptomycin resistance affects ribosomal structure, whereas low-level resistance involves a change in membrane permeability.

Can J Microbiol, 1977 Sep, 23(9), 1274 - 84
Polarity in the exponential-phase Rhizobium japonicum cell; Tsien HC et al.; Highly distinctive aspects of the exponentail-phase Rhizobium japonicum cell were disclosed by means of thin sections, freeze etching, fluorescent antibodies, and ruthenium red staining . Polarity was expressed in the form of reserve polymer distribution near one end of the cell and as cytoplasmic localization near the opposite end . In addition, exocellular polysaccharide (EPS) accumulated preferentially around the cytoplasmic end, and the feature described previously as an "immunofluorescent polar tip" was seen clearly as an extracellular polar body (EPB) on the tip of the cell at the reserve polymer end . Compartmentalization of cytoplasm and reserves were consistent features of nearly all exponential cells of the two strains studied; strain 31, however, formed little EPS and had a high incidence of a large, tightly bound EPB, while strain 138 formed EPS extensively and had a low incidence of EPB . Extracellular polysaccharides of strain 138 reacted with soybean lectin in gel diffusion tests, so that the EPS seen in electron micrographs is tentatively considered to include the lectin-binding material . Extracellular polar bodies were accumulations of granular and fibrillar material with properties consistent with the presence of polysaccharide and lipopolysaccharide . The role of EPB in cell to cell attachment was confirmed by electron microscopy.

Mikrobiologiia, 1977 Sep-Oct, 46(5), 960 - 4
{Transformation of L-tryptophan by Rhizobium phaseoli}; Sabel'nikova VI et al.; Transformation of L-tryptophan was studied in Rhizobium phaseoli 680 . The culture was capable of oxidation decarboxylation, transamination and degradation of L-tryptophan . Four metabolites were identified: tryptamine, indolyl-3-pyruvic, indolyl-3-acetic and anthranilic acids . The fifth metabolite has not been yet identified.

Can J Microbiol, 1977 Sep, 23(9), 1118 - 22
Comparison of colony morphology, salt tolerance, and effectiveness in Rhizobium japonicum; Upchurch RG et al.; Four strains of Rhizobium japonicum, two of which produce slimy and non-slimy colony types and two others which produce large and small colony types, were isolated and cloned . All were infective and nodulated Lee soybean host plants . Each colony type was characterized as to its salt sensitivity to Na+ and K+ ions, relative level of symbiotic nitrogen fixation, and relative level of free-living nitrogen fixation . Growth studies performed in the presence of salts demonstrated that the non-slimy or small colony types were sensitive to salt with significantly depressed growth rates and cell yields . Growth rates and cell yields of slimy, large, colony types were relatively unaffected by salt . Both symbiotic and free-living (non-associative) nitrogen fixation analyses (by acetylene reduction) revealed that the non-slimy, small colonies were significantly more effective than slimy, large colonies.

Can J Microbiol, 1977 Sep, 23(9), 1178 - 81
{Demonstration of 2 enzymes with beta-galactosidase activity in Rhizobium meliloti}; Niel C et al.; The beta-galactosidase (EC 3.2.1.23) activities of wild-type Rhizobium meliloti and its lactose slow-hydrolyzing mutant have been compared . The properties of the enzyme are very different in each strain . These differences allow us to prove that two enzymes with a beta-galactosidase activity can be found in the wild-type whereas only one enzyme remains in the mutant strain.

Can J Microbiol, 1977 Sep, 23(9), 1165 - 9
Flow-microfluorometric analysis of Escherichia coli, Rhizobium meliloti, and Rhizobium japonicum at different stages of the growth cycle; Paau AS et al.; The applicability of flow-microfluorometry (FMF) to the study of bacterial samples was investigated on cultures of Rhizobium meliloti, Rhizobium japonicum, and Escherichia coli using fluorescent and light-scattering signals . This technique which analyzes individual bacterial cells in a population was used to monitor the relative change in nucleic acid content and cell size during the growth cycle of the three microorganisms which were known to have different growth rates . Early log-phase E . coli cells contained at least eightfold more nucleic acid and were significantly larger than the stationary-phase cells . Cultures of early log-phase R . meliloti cells contained three to four-fold more nucleic acid and were slightly larger than cells in the stationary phase . Rhizobium japonicum had very little change in either parameter . In general, the amount of change in both cell size and nucleic acid content upon initiation of log-phase growth was related to the overall growt rate of the organisms, with E . coli experiencing the greatest change and R . japonicum the least . Results obtained by FMF analysis, therefore, were consistent with observations reported by earlier workers . Cultures of R . meliloti also were used to demonstrate that the intensity of the fluorescent signals was sensitive to digestion by DNase and RNase and to prolonged storage and fixation . The potential use of FMF in the study of microorganisms is discussed.

Can J Microbiol, 1977 Sep, 23(9), 1293 - 8
The role of 6-phosphogluconate dehydrogenase in Rhizobium; Mulongoy K et al.; A nicotinamide adenine dinucleotide (NAD) linked 6-phosphogluconate (6-PG)dehydrogenase has been detected in Rhizobium . The enzyme activity is similar in both slow- and fast-growing rhizobia . The nicotinamide adenine dinucleotide phosphate (NADP) dependent 6-PG dehydrogenase was detected only in the fast growers and was more than twice as active as the NAD-linked enzyme . Partial characterization of the products of 6-PG oxidation in Rhizobium suggests that the NADP-linked enzyme is the decarboxylating enzyme of the pentose phosphate (PP) pathway (EC 1.1.1.44) whereas a phosphorylated six-carbon compound, containing ketonic group(s), is the product of the oxidation catalyzed by the NAD-linked enzyme.

Can J Microbiol, 1977 Aug, 23(8), 1026 - 33
Symbiotic effectiveness of antibiotic-resistant mutants of fast- and slow-growing strains of Rhizobium nodulating Lotus species; Pankhurst CE; Mutants resistant ot 16 individual antibiotics were isolated from two fast-growing and two slow-growing strains of Lotus rhizobia and their symbiotic effectiveness on Lotus pedunculatus evaluated . Resistance to streptomycin, spectinomycin, chloramphenicol, and tetracycline (inhibitors of protein synthesis) was associated with little or no loss of effectiveness with all four strains but resistance to nalidixic acid and rifampicin (inhibitors of nucleic acid synthesis), and to D-cycloserine, novobiocin, and penicillin (inhibitors of cell wall-cell membrane synthesis) was associated with significant loss of effectiveness in 20-100% of the mutants . Resistance to viomycin, neomycin, kanamycin, and vibramycin was associated with loss of effectiveness with mutants of the two fast-growing strains but not with mutants of the two slow-growing strains . When tested on four alternate host legumes individual mutants of a slow-growing strain showed significantly different levels of effectiveness . The results suggest that both the inherent characteristics of the bacterium and of the host plant will influence the symbiotic effectiveness of antibiotic-resistant mutants of Rhizobium.

Bull Environ Contam Toxicol, 1977 Aug, 18(2), 190 - 9
Effects of pesticide seed treatments on Rhizobium japonicum and its symbiotic relationship with soybean; Tu CM; Seventeen Rhizobium japonicum cultures isolated from soybean nodules induced formation of nodules on taproots of soybean plants . All isolates reduced acetylene to ethylene to different extents in vitro . Paper disc assay indicated that two insecticides, lindane (gamma-1,2,3,4,5,6-hexachlorocyclohexane), chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate), and a fungicide, thiram (tetramethylthiuram disulphide) individually or in combination caused significant inhibition of the growth of R . japonicum No . 16 . The effects of insecticide-fungicide seed treatments on the nitrogenase activity of soybean plants in nitrogen-fixing capacity, weights of leaves, stems, and nodules were determined . Thiram, singly or in combination with lindane and/or chlorpyrifos, significantly delayed growth of the plants and affected the activity of nitrogenase in the fixation of nitrogen 3 weeks after treatments . No drastic effect of any of the pesticide treatments on soybean plant growth was observed after 8 weeks.

Mikrobiologiia, 1977 Jul-Aug, 46(4), 770 - 2
{Electrophoretic characteristics of the protein composition of mutant forms of pea nodular bacteria}; Nalbandian AD et al.; A water-soluble protein fraction was studied by gel electrophoresis in the parent and mutant forms of the nodule bacterium Rhizobium leguminosarum . The composition of this fraction changed under the action of NTG . Changes in the composition of protein components in the mutants as compared with that of the parent strain are caused presumably by their modified specificity.

Mikrobiologiia, 1977 Jul-Aug, 46(4), 737 - 40
{Change in phage sensitivity in Rhizobium meliloti transformants}; Zaretskaia AN et al.; Cultures of Rhizobium meliloti were studied in order to test their phage resistance . Seven variants of the modification of phage resistance were found among the transformants under study, and an attempt was made to interpret them.

J Bacteriol, 1977 Jul, 131(1), 179 - 87
Glucose catabolism in two derivatives of a Rhizobium japonicum strain differing in nitrogen-fixing efficiency; Mulongoy K et al.; Radiorespirometric and enzymatic analyses reveal that glucose-grown cells of Rhizobium japonicum isolates I-110 and L1-110, both derivatives of R . japonicum strain 3I1b110, possess an active tricarboxylic acid cycle and metabolize glucose by simultaneous operation of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways . The hexose cycle may play a minor role in the dissimilation of glucose . Failure to detect the nicotinamide adenine dinucleotide phosphate-dependent decarboxylating 6-phosphogluconate dehydrogenase (EC 1.1.1.44) evidences absence of the pentose phosphate pathway . Transketolase and transaldolase reactions, however, enable R . japonicum to produce the precursors for purine and pyrimidine biosynthesis from fructose-6-phosphate and glyceraldehyde-3-phosphate . A constitutive nicotinamide adenine dinucleotide-linked 6-phosphogluconate dehydrogenase has been detected . The enzyme is stimulated by either mannitol or fuctose and might initiate a new catabolic pathway . R . japonicum isolate I-110, characterized by shorter generation times on glucose and greater nitrogen-fixing efficiency, oxidizes glucose more extensively than type L1-110 and utilizes preferentially the Embden-Meyerhof-Parnas pathway, whereas the Entner-Doudoroff pathway apparently predominates in type L1-110.

Arch Microbiol, 1977 Jun 20, 113(3), 181 - 3
Further evidence for the regulation of bacterial populations in soil by protozoa; Habte M et al.; After the addition to soil of large numbers of a cowpea Rhizobium strain, the population declined steadily until the numbers reached about 10(7)/g, and the protozoa rose to about 10(4)/g . When indigenous protozoa were suppressed by the addition of actidione to the soil, the density of the test rhizobium did not fall initially, but its abundance declined to about 10(7)/g when actidione-resistant protozoa arose in significant numbers . The addition to actidione-treated soil of an antibiotic-resistant strain of Paramecium led to a rapid decrease in the population of the rhizobium, the density reaching essentially the same value as in soil receiving neither the drug nor the paramecia . The same changes occurred with Xanthomonas campestris as test prey except that its numbers fell to about 10(5)/g of soil . These data provide further evidence for the key role of protozoa in controlling the abundance of populations of certain bacteria introduced into soil.

J Bacteriol, 1977 Jun, 130(3), 1139 - 43
6-Phospho-D-gluconate:NAD+ 2-oxidoreductase (decarboxylating) from slow-growing Rhizobia; Martinez-Drets G et al.; 6-Phospho-D-gluconate:NAD+ 2-oxidoreductase (decarboxylating) (NAD+-6PGD) was detected in several slow-growing strains of rhizobia, and no activity involving NADP+ was found in the same extracts . By contrast, fast-growing strains of rhizobia had NADP+-6PGD activity; most of them also had NAD+-6PGD activity . NAD+-6PGD was partially purified from the slow-growing strain Rhizobium japonicum 5006 . The reaction was shown to be an oxidative decarboxylation.

Mikrobiologiia, 1977 May-Jun, 46(3), 560 - 3
{Serologic properties of mutants of Rhizobium trifolii and their interrelationship with effectiveness}; Cheverda MG et al.; UV and gamma irradiation of Rhizobium trifolii, strains 347a and 311a, produced their mutants with changed antigenic properties and effectiveness . The extent of changes of antigens did not depend on the dose of irradiation because mutants that completely lost antigens typical of the parent strains were obtained at different doses of UV and gamma rays . No correlation was established between the antigenic properties of the mutants of Rhizobium trifolii and their effectiveness.

Rev Asoc Argent Microbiol, 1977 May-Aug, 9(2), 62 - 7
{Production of inoculates for leguminous plants . Production of cellular suspensions of Rhizobium (Lotus group)}; Balatti AP et al.; The influence of culture medium composition and operative conditions on the cellular growth of Rhizobium sp (group Lotus) strain is studied . As much as 1 x 10(9) cell/ml were obtained in 16 hours using sucrose in the medium as carbon source . The best growth rate was obtained (mu = O,22 h-1) when the experiments were performed at 400 r.p.m . and one volume of air/volume of medium x minute (OAR = 793,0 ml of oxygen/1 h).

Can J Microbiol, 1977 May, 23(5), 573 - 82
Ultrastructure of soybean nodules . I: release of rhizobia from the infection thread; Bassett B et al.; Root nodules on soybeans (var . Clark 63) were examined by transmission electron microscopy 10-12 days after seed inoculation and planting . The cell infection process appeared identical in both effective nodules, induced by Rhizobium japonicum strain 138 (USDA) and in ineffective nodules, induced by strain 8-0 (Iowa) . Electron micrographs are presented which suggest that rhizobia are freed from the infection thread by disintegration of the thread wall and compartmentalization of the distintegrated wall material in membrane-bound vesicles derived from the membrane surrounding the thread . As the thread wall is removed in this manner, the bacteria are released into the host cytoplasm by a process which encloses each in an envelope also dervide from the thread membrane . Any thread wall material remaining around a bacterium after it has dissociated from the thread is removed from the envelope space by vesiculation of the membrane envelope . thus, it appears that endocytosis of both the bacteria and the material composing the infection thread wall occurs during release of rhizobia into the host cell.

Proc Natl Acad Sci U S A, 1977 May, 74(5), 2076 - 8
Genetic mapping of Rhizobium meliloti; Meade HM et al.; The drug resistance factor RP4, originally isolated in Pseudomonas, was transferred to Rhizobium meliloti . In that strain, RP4 promotes conjugational transfer of chromosomal markers to form haploid recombinants . This mating system has been used to construct a linkage map of R . meliloti.

Appl Environ Microbiol, 1977 Apr, 33(4), 784 - 90
Resistance of Rhizobium strains to phygon, spergon, and thiram; Odeyemi O et al.; Strains of Rhizobium meliloti, Rhizobium sp . nodulating cowpeas, and R . phaseoli derived from cultures susceptible to tetramethylthiuram disulfide (thiram), 2,3-dichloro-1,4-naphthoquinone (phygon), and 2,3,5,6-tetrachloro-p-benzoquinone (spergon), respectively, grew in the presence of high concentrations of the fungicides and converted them to products not toxic to the sensitive rhizobia . The results of chemical assays demonstrated that the pesticides were destroyed by the resistant bacteria but not by the susceptible parent rhizobia . Resting cells of thiram-metabolizing R . meliloti formed large quantities of dimethyldithiocarbamate, dimethylamine, and CS2 from the pesticide . The products were characterized by gas and thin-layer chromatography, colorimetric reactions, and ultraviolet spectrometry . Dimethylamine and CS2 were formed spontaneously from dimethyldithiocarbamate, but the yield was higher in the presence of R . meliloti . The phygon-resistant bacterium converted the fungicide to five metabolites and thereby rendered the chemical nontoxic to a test fungus . The resistant strain of R . phaseoli generated at least one organic product and released about one-third of the chlorine during its detoxication of spergon.

Aust J Biol Sci, 1977 Apr, 30(1-2), 141 - 53
Effect of dimethyl sulphoxide on the expression of nitrogen fixation in bacteria; Skotnicki ML et al.; Storage in dimethyl sulphoxide (DMSO) of Escherichia coli K12 hybrids carrying nif+ genes from Klebsiella pneumoniae can result in selection of a defective nitrogen-fixing phenotype . Similar results are obtained with E . coli K12 hybrids containing the nitrogen-fixing capacity from Rhizobium trifolii . DMSO appears to affect particular inner membrane proteins associated with energy metabolism in E . coli K12 and four chromosomal regions (chlD, chlG, his and unc) are associated with resistance to DMSO.

J Bacteriol, 1977 Feb, 129(2), 718 - 23
Nitrogen fixation in nitrate reductase-deficient mutants of cultured rhizobia; Pagan JD et al.; Forty-eight mutants unable to reduce nitrate were isolated from "cowpea" Rhizobium sp . strain 32Hl and examined for nitrogenase activity in culture . All but two of the mutants had nitrogenase activity comparable with the parental sttain and two nitrogenase-defective strains showed alterations in their symbiotic properties . One strain was unable to nodulate either Macroptilium atropurpureum or Vigna uguiculata and, with the other, nodules appeared promptly, but effective nitrogen fixation was delayed . These results, and the relatively low proportion of nitrate reductase mutants with impaired nitrogenase activity, do not support the proposed commanality between nitrogenase and nitrate reductase in cowpea rhizobia . Inhibition studies of the effect of nitrate and its reduction products on the nitrogenase activity in cultured strains 32Hl and the nitrate reductase-deficient, Nif+ strains, indicated that nitrogenase activity was sensitive to nitrite rather than to nitrate.

J Bacteriol, 1977 Feb, 129(2), 1156 - 8
Comparison of nucleic acid content in populations of free-living and symbiotic Rhizobium meliloti by flow microfluorometry; Paau AS et al.; Populations of symbiotic Rhizobium meliloti extracted from alfalfa nodules were shown by flow microfluorometry to contain a significant number of bacteroids with higher nucleic acid content than the free-living rhizobia . Bacteroids with lower nucleic acid content than the free-living bacteria were not detected in significant quantities in these populations . These results indicate that the incapability of bacteroids to reestablish growth in nutrient media may not be caused by a decrease in nucleic acid content of the symbiotic rhizobia.

Mol Gen Genet, 1977 Jan 7, 150(1), 73 - 9
Formation of merodiploid clones by cojugation in Rhizobium lupini; Heumann W et al.; Off the transconjugants formed in the R . lupini conjugation 0.5 to 5% are merodiploids . When two differently pigmented parents are used in the crossing experiment the diploid transconjugants by their additive pigmentation type . The segregation patterns of these diploid clones were analyzed . The results are in agreement with the theory that the exogenotic donor DNA can be integrated at different sites of the homologous recipient chromosomal region forming a tandem sequence . Consequently the segregants of these merodiploid clones are formed by endochromosomal recombination.

Mikrobiologiia, 1977 Jan-Feb, 46(1), 149 - 54
{Effect of humus and microbial inoculates on yield and nitrogen uptake by agricultural plants}; Madur RS et al.; The application of humus had a positive effect on grain and straw yield of paddy and the yield increased with the increasing concentration of humus . The highest dose ((0,05%) corresponding to 1120 kg humus/ha significantly increased the grain and straw yield by 85 and 30 per cent over control . The efficiency of algal inoculation was enhanced in the presence of humus and recorded 41 per cent increase in yield over algae . The nitrogen uptake was also appreciably increased by grain and straw due to humus application . Humus at 0,05 per cent along with algae significantly increased the nitrogen uptake by paddy over algae alone . Root nodulation, growth and yield of gram crop were appreciably increased due to humus application . The grain and straw yield were increased due to humus (0,05%) application showing 32 and 41 per cent increase over control . The efficiency of Rhizobium inoculation was also improved in the presence of humus and the grain and straw yield was significantly increased.

J Gen Virol, 1977 Jan, 34(1), 9 - 17
Bacteriophage 7-7-1 adsorbs to the complex flagella of Rhizobium lupini H13-3; Lotz W et al.; Bacteriophage 7-7-1 is shown to adsorb specifically to the complex flagella of its host Rhizobium lupini H13-3 . Deflagellation of motile cells before the addition of phage leads to a complete inhibition of phage propagation for at least 60 min . Among phage-resistant mutants, many non-motile (mot) and non-flagellated (fla) derivatives of R . lupini H13-3 have been selected . Electron microscopic observations indicate that bacteriophage 7-7-1 attaches with its short tail fibres to the conspicuous helical filament of R . lupini flagells . This attachment is reversible; irreversible phage adsorption takes place at the flagellar base . It is postulated that phage 7-7-1 moves along the rotating flagellum towards a final receptor next to the insertion site of the flagellum, where tail contraction and injection of phage nucleic acid occurs.

Microbios, 1977, 20(79), 15 - 28
Differential stimulation and inhibition of growth of Rhizobium trifolii strain T1 and other Rhizobium species by various carbon sources; Skotnicki ML et al.; The physiological properties of Rhizobium trifolii strain T1 were studied in detail, since this strain has many useful characteristics and appears ideal for development as a reference strain for R . trifolii . Some tricarboxylic acid cycle intermediates and related compounds were found to stimulate growth in the presence of sucrose and arabinose, while others inhibited growth partially or completely . Other R . trifolii strains behaved likewise . Moreover, similar responses were also observed with other Rhizobium species, both fast-growing and slow-growing . On the basis of these growth responses, the various species of fast-growing and slow-growing rhizobia could be differentiated . Of the fast-growers tested, R . trifolii and R . leguminosarum are much more closely related to each other than either is to R . meliloti . Similarly, the slow-growing cowpea rhizobia are more closely related to R . japonicum than either group is to R . lupini . It is proposed that strain T1 should be developed as the reference strain for Rhizobium trifolii.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1977, 132(5-6), 400 - 6
{Studies concerning the biology of rhizobia . 1 . Communication: serological investigations (author's transl)}; Manninger E; According to earlier studies the strains of the rhizobia could be put into three biochemical groups (A, B, C) independently of the nodules of which kind of plants having been isolated from . The aim of our experiments has been the determination of the antigenic structure of these rhizobia strains . Regarding the agglutination tests only 24 strains from the 47 ones were agglutinated by A sera, one B strain from the 3 B ones, and 2 C strains from the C ones gave positive reaction with B and C sera, respectively.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1977, 132(4), 350 - 60
Certain environmental factors affecting rhizobia and symbiotic systems; Hamdi YA; The interrelation between rhizobia and certain fungi, bacteria, actinomycetes, nematodes, and seed-coat diffusates of Phaseolus vulgaris were investigated . The effect of pesticides, i.e . fungicides, herbicides, and nematocides on growth of rhizobia, and the symbiotic systems between rhizobia and their respective host is reported . Degradation of certain herbicides and insecticides is shown . The movement of rhizobia in soil as affected by water tension, tolerance of salts, and soil temperatures are discussed . Environmental factors may affect the successful establishment of an effective symbiosis between rhizobia and their hosts at any or all the three stages . They may 1) affect occurrence, growth, and survival of root nodule bacteria, 2) modify nodule formation, or 3) affect the function of the formed nodules (VINCENT 1962) . The environmental aspect considered here include the antagonistic factors against rhizobia, the pesticides, and some ecological aspects of rhizobia in soil, e.g., the movement and salts and heat tolerance . These aspects were investigated by Egyptian workers over the period 1948-1972 . Comprehensive reviews on the effect of environmental factors on rhizobia were reported by VINCENT (1962) and NUTMAN (1972).

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1977, 132(7), 623 - 7
Stepwise selection of efficient rhizobial cultures through cultural characteristics; Balasundaram VR et al.; Nodulation and shoot nitrogen of two varieties of soybean (Glycine max) were studied with twenty strains of Rhizobium japonicum . A number of cultural characteristics of the strains in isolation to the symbiotic system were also studied . A stepwise selection method was employed for detecting efficient cultures through the cultural characteristics which showed association with the steps in the symbiotic system . Nodulation of one variety was found to be associated with the dehydrogenase activity and the growth of microbes in the medium containing soil extract, whereas the nodulation of another variety showed association with the growth in the media containing asparagine and tryptophane . The shoot nitrogen of one nodulated cultivar correlated with the microbial growth in Elkan's medium in the medium containing serine and glucose, whereas the shoot nitrogen of the other nodulating variety correlated with the growth of the cultures in the medium containing aspartic acid . The validity of this approach to the problem for detecting efficient strains through cultural characteristics was discussed.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1977, 132(7), 616 - 22
Grouping of rhizobial strains--a method based on symbiotic characteristics; Balasundaram VR et al.; Twenty strains of Rhizobium japonicum and non-inoculated control were used to study seven symbiotic characteristics with two varieties of soybean (Glycine max) . The strains were then grouped on the basis of these symbiotic characteristics, using Mahalanobis' D2 statistical method . Eight groups were formed in which two strains stood distinctly aloof, indicating thereby the exceptional nature of these strains over others in their symbiotic behaviour . This method is suggested for selecting exceptional strains for particular symbiotic characteristics as well as for greater N fixing efficiency with varieties and for different agroclimatic conditions.

J Gen Microbiol, 1977 Jan, 98(1), 253 - 63
Introduction of bacteriophage Mu into Pseudomonas solanacearum and Rhizobium meliloti using the R factor RP4; Boucher C et al.; Phage Mu-1 and a thermoinducible derivative, Mu-1 cts 62 were inserted into the broad host range R factor RP4 . These hybrid plasmids were transferred by conjugation to a phytopathogenic bacterium Pseudomonas solanacearum GMI 1000 and a legume-root nodule bacterium Rhizobium meliloti 2011 . The Mu genome is transcribed and tranlated in these new hosts: P . solanacearum (RP4:Mu cts) cultures have a spontaneous production of about 5 X 10(5) plaque-forming units ml-1 which is similar to the frequency of spontaneous Mu production in E . coli; the Mu production of R . meliloti is lower (about 10(2) plaque-forming units ml-1).

Acta Microbiol Pol, 1977, 26(4), 351 - 9
Structure of nodules induced by auxotrophic and ineffective mutants of Rhizobium meliloti strain L5-30 requiring cysteine, arginine+uracil and histidine; Malek W et al.; Nodules produced by ineffective mutants of R . meliloti strain L5-30 requiring arginine+uracil (arg-55) and cysteine requiring mutants (cys-243, cys-244, cys-246) studied under light microscopy were found to be occupied by bacteria . This indicates on defect in transformation of these mutants into N2 fixing bacteroids . These defects were not associated with auxotrophy . In the nodules induced by histidine requiring mutant (his-240) only few host plant cells were occupied by bacteria . This indicate that his-240 mutant is defective in liberation from the infection thread and its multiplication since supplementation of the plant growth medium with 50 microgram/ml of L-histidine enabled establishment of fully effective association . Prototrophic transductants and revertants were fully effective.

Acta Microbiol Pol, 1977, 26(4), 345 - 50
Auxotrophic mutations related to symbiotic properties of Rhizobium meliloti strain L5-30; Malek W et al.; Mutants isolated from effective R . meliloti strain L5-30 which required histidine (his-240), arginine+uracil (arg-55) and cysteine (cys-243, cys-244 and cys-246) showed also loss of effectiveness . Mutant requiring isoleucine+valine (ilv-74) was non-infective . Relation of the metabolic deficiency to the symbiotic properties of these mutants was tested comparing symbiotic response of their prototrophic revertants and transductants . It was found that all revertants and transductants of the strain his-240 were effective which suggests that histidine deficiency was the cause of their ineffectiveness . All revertants and transductants of the cysteine mutants were still ineffective . This result indicates two independent mutations which were not cotransductible . Prototrophic revertants of the mutant arg-55 were ineffective whereas 56.9 percent of transductants appeared effective suggesting close linkage of two mutations . i.e . auxotrophic and the other concerned with symbiotic effectiveness . Though one of 69 prototrophic transductants obtained from the non-nodulating mutant ilv-74 remained non-nodulating, it seems that changes in nodulating ability of the mutant are related to the auxotrophic requirements.

Acta Microbiol Pol, 1977, 26(3), 233 - 41
Correlation between streptomycin resistance and symbiotic properties of Rhizobium . I . Conversion of spheroplastizing, effective R . trifolii strain B1 to avirulent rods with changed phage and antibiotic patterns after mutation to high level of streptomycin resistance; Zelazna-Kowalska I; Rhizobium trifolii strain B1, which is infective and fixes nitrogen during symbiosis with clover plants, shows a peculiar property to undergo morphological change during growth, i.e . rods are changing into spheroplast-like forms . Moreover, it failed to grow at 38 degrees . It was found that mutation to high level of streptomycin resistance (above 1000 microgram per/ml) caused loss of this property . Further studies showed that simultaneously with the changes in streptomycin resistance other features of this strain were also changed: infectivity for clover plants, sensitivity to high temperature, phages and antibiotics . Mutation to low level of streptomycin resistance did not change the above mentioned features of the strain B1.

Acta Microbiol Pol, 1977, 26(1), 9 - 18
Transfer of R1drd19 plasmid from Escherichia coli J53 to Rhizobium trifolii by conjugation; Kowalczuk E et al.; Rldrd19 plasmid was transferred by conjugation from Escherichia coli J53 to Rhizobium trifolii T24, T26 and 24XSM strains with frequency 10(-3) to 10(-5) . The R . trifolii exconjugants carrying Rldrd19 were in turn able to transfer the R factor by conjugation to other R . trifolii strains . Rldrd19 was maintained stably in R . trifolii . R . trifolii 24XSM, T26 and 14M were also found to harbor an endogenous plasmid (molecular weight 5.5 megadaltons) with undetermined as yet properties . Ridrd19 could be stably maintained in the same cell together with the endogenous plasmid.

Biochim Biophys Acta, 1976 Dec 21, 451(2), 342 - 52
Control of synbiotic nitrogen fixation in Rhizobia . Regulation of NH4+ assimilation; O'gara F et al.; This communication is concerned with physiological, biochemical, and genetic studies of the regulation of ammonium (NH4+) assimilation by Rhizobia (root nodule bacteria) that infect leguminous plants . The major conclutions are (i) physiological studies show that Rhizobia are able to assimilate NH4+ for growth only when supplemented with certain organic nitrogen sources (e.g., L-aspartate, L-leucine, L-serine) . Addition of as little as 2 mug/ml of L-aspartate supported growth on NH4+ as nitrogen source . In contrast, addition of glutamate in combination with NH4+-blocked NH4+ utilization; (ii) biochemical analysis show that glutamate synthase activity (NADP- and NAD-linked) is always present in cells capable of assimilating NH4+; also cells without glutamate synthase activity were found to be incapable of NH4+ utilization . Glutamate synthase levels were observed to fluctuate markedly depending on the available nitrogen source and on the growth stage of the culture; (iii) mutants were selected in which assimilation of NH4+ is no longer subject to inhibition (repression?) by glutamate . The levels of glutamate synthase activity (NADP-linked) (in the presence of glutamate) show approximately a two-fold increase over the level in the parent strain . The mutants no longer require supplementation with small amounts of organic nitrogen for growth in medium containing inorganic nitrogen (e.g., NH4+ or NO3-); (iv) these findings are discussed in relation to the working model of symbiotic nitrogen fixation recently proposed (O'Gara and Shanmugam (1976), Biochim . Biophys . Acta 437, 313--321).

C R Acad Sci Hebd Seances Acad Sci D, 1976 Nov 22, 283(13), 1559 - 62
{Demonstration of different metabolic pathways starting with glucose or fructose in Rhizobium meliloti}; Hornez JP et al.; Rhizobium meliloti can produce many polysaccharides on D-fructose and D-mannitol . In glucose-grown cultures, few polysaccharides are observed and 2 keto-gluconate is accumulated.

Mikrobiologiia, 1976 Nov-Dec, 45(6), 1107 - 10
{Survival of Rhizobium meliloti in soil studied by genetic labeling}; Imshenetskii AA et al.; The number of cells of a mutant of Rhizobium meliloti resistant to streptomycin decreased to 10(6) per 1 g of soil during 3-5 days and remained at this level for at least a month when 10(8) cells of the mutant per 1 g were introduced into non-sterile soil . Factors causing such a stability of the population are discussed.

J Gen Microbiol, 1976 Oct, 96(2), 247 - 51
Nitrate reductase from anaerobically grown Rhizobium japonicum; Daniel RM et al.; The activity of nitrate reductase in Rhizobium japonicum is controlled by oxygen tension, and not by nitrate . The enzyme from R . japonicum grown anaerobically in the presence of nitrate resembles that from bacteroids in having a molecular weight of about 69000 daltons; the enzyme from aerobically grown cells ahs a molecular weight of about 170000 daltons . Both types of enzyme have similar Km values, but differ in their sensitivity to KCN.

Appl Environ Microbiol, 1976 Oct, 32(4), 511 - 9
Rhizobium japonicum derivatives differing in nitrogen-fixing efficiency and carbohydrate utilization; Kuykendall LD et al.; Four derivatives of Rhizobium japonicum 110 were isolated on the basis of morphologically different colonies formed on yeast extract-mannitol-HM salts medium . All are able to nodulate Lee soybeans . The bacteria-plant associations formed by each clone have measurable acetylene-reducing activity, but those formed by two of these clones (designated L1-110 and L2-110) are 5- to 10-fold less efficient than those formed by the others (designated I-110 and S-110) . These derivatives were not detectable with ordinary culture techniques since, because of cell adherence, genetically mixed colonies result . When a detergent (Tween 40 at 0.01%, vol/vol) was added to the dilution medium, separate clones resulted . The metabolic basis for the gross differences in colony morphology on yeast extract-mannitol-HM salts medium was found to be that L1-110 and L2-110 utilized p-mannitol for growth, whereas I-110 and S-110 did not . These clones differ analogously in ability to utilize D-arabitol . Clones I-110 and L1-110 were chosen for studies of growth rates on various carbohydrates . Although clone I-110 and clone L1-110 did not differ in growth rates on a number of sugars, such as gluconate, arabinose, glycerol, and mannose, they differed in growth rates on glucose and fructose . Although clone I-110 grew faster on glucose than did clone L1-110, clone L1-110 grew faster on fructose than did clone I-110 . Clones I-110 and L1-110 showed identical responses to several antibiotics and deoxyribonucleic acid (DNA) synthesis inhibitors and identical susceptibility to some highly specific bacteriophages . Identical buoyant densities of their DNAs in isopycnic CsCl density gradients and identical thermal denaturation temperatures of their DNAs suggest that clones I-110 and L1-110 have the same DNA base composition . Preliminary DNA/DNA hybridization experiments show that strain I-110 DNA and strain L1-110 DNA have a high degree of common polynucleotide sequences.

Appl Environ Microbiol, 1976 Oct, 32(4), 483 - 8
Regulation of nitrogen fixation in Rhizobium sp; Tubb RS; Regulation of nitrogen fixation by ammonium and glutamate was examined in Rhizobium sp . 32H1 growing in defined liquid media . Whereas nitrogenase synthesis in Klebsiella pneunoniae is normally completely repressed during growth on NH4+, nitrogenase activity was detected in cultures of Rhizobium sp . grown with excess NH4+ . However, an "ammonium effect" on activity was invariably observed in cultures grown on NH4+ as sole nitrogen source; the nitrogenase activity was, depending on conditions, 14 to 36% of that of comparable glutamate-grown cultures . Glutamate inhibited utilization of exogenous NH4+ and, in one of two procedures described, glutamate partially alleviated the ammonium effect on nitrogenase activity . NH4+, apparently produced from N2, was excreted into the culture medium when growth was initiated on glutamate, but not when NH4+ was thesole source of fixed nitrogen for growth . These findings are discussed in relation to nitrogen fixation by Rhizobium bacteroids.

J Bacteriol, 1976 Oct, 128(1), 481 - 4
Plasmid deoxyribonucleic acid in Rhizobium trifolii; Zurkowski W et al.; In deoxyribonucleic acid of Rhizobium trifolii centrifuged in cesium chloride-ethidium bromide equilibrium was found a sattelite peak containing covalently closed circular deoxyribonucleic acid . The plasmid had a molecular weight of about 64 x 10(6) shown by sedimentation in sucrose gradients and electron microscopy.

Biochim Biophys Acta, 1976 Aug 24, 444(1), 164 - 74
Nitrogenase activity and respiration of cultures of Rhizobium spp . with special reference to concentrations of dissolved oxygen; Bergersen FJ et al.; Studies of nitrogenase in cultures of the cowpea rhizobia (Rhizobium spp.) strains 32H1 and CB756 are reported . Preliminary experiments established that, even when agar cultures were grown in air, suspensions of bacteria prepared anaerobically from them were most active at low concentrations of free dissolved O2 . Consequently, assays for activity used low concentrations of O2, stabilized by adding the nodule pigment leghaemoglobin . In continuous, glutamine-limited cultures of 32H1, nitrogenase activity appeared only when the concentration of dissolved O2 in the cultures approached 1 muM . Lowering the glutamine concentration in the medium supplied to the culture from 2 to 1 mM halved the cell yield and nitrogenase activity was also diminished . Omitting succinate from the medium caused the concentration of dissolved O2 to rise and nitrogenase activity was lost . Upon restoration of the succinate supply, the O2 concentration immediately fell and nitrogenase was restored . The activity doubled in about 8 h, whereas the doubling time of this culture was 14 h . Sonic extracts of 32H1 cells from continuous cultures with active nitrogenase contained components reacting with antiserum against nitrogenase Mo-Fe protein from soybean bacteroids . Continuous cultures grown at higher O2 concentration, with only a trace of active nitrogenase, contained less of these antigens and they were not detected in highly aerobic cultures . Nitrogenase activity of a continuous culture was repressed by NH+4; the apparent half-life was about 90 min . Cells of 32H1 from a continuous culture growing at between 30 and 100 muM dissolved O2 possessed a protective mechanism which permitted respiration to increase following exposure to a rapid increase in O2 concentration from low levels (O2 shock) . This effect disappeared as the O2 concentration for growth was reduced towards 1 muM.

J Bacteriol, 1976 Aug, 127(2), 763 - 9
Ineffective and non-nodulating mutant strains of Rhizobium japonicum; Maier RJ et al.; Mutant strains of Rhizobium japonicum that were unable to allow the Corsoy cultivar of soybean to reduce acetylene or fix N2 were isolated . These strains grow as well as the wild type in a variety of media . Mutant strains SM1 and SM2 did not form nodules on the host plant; however, they reduced acetylene in the nonsymbiotic assay . Strains SM3 and SM4 produced nodules that did not have the characteristic pink pigment caused by leghemoglobin . The nodules formed by these strains also were small . One mutant strain, SM5, produced large pink nodules . The lesion in this strain seems to be in the gene that specifies nitrogenase component II.

Biochim Biophys Acta, 1976 Jul 21, 437(2), 313 - 21
Regulation of nitrogen fixation by Rhizobia . Export of fixed N2 as NH+4; O'Gara F et al.; The metabolic fate of gaseous nitrogen (15N2) fixed by free-living cultures of Rhizobia (root nodule bacteria) induced for their N2-fixation system was followed . A majority of the fixed 15N2 was found to be exported into the cell supernatant . For example, as much as 94% of the 15N2 fixed by Rhizobium japonicum (soybean symbiont) was recovered as 15NH+4 from the cell supernatant following alkaline diffusion . Several species of root nodule bacteria also exported large quantities of NH+4 from L-histidine . Evidence is presented that overproduction and export of NH+4 by free-living Rhizobia may be closely linked to the control of several key enzymes of NH+4 assimilation . For instance, NH+4 was found to repress glutamine synthetase whereas L-glutamate repressed glutamate synthase . Assimilation of NH+4 as nitrogen source for growth of Rhizobia was inhibited by glutamate . The mechanism of regulation of NH+4 production by root nodule bacteria is discussed.

Appl Environ Microbiol, 1976 Jul, 32(1), 166 - 71
Adsorption of bacteria to roots as related to host specificity in the Rhizobium-clover symbiosis; Dazzo FB et al.; Quantitative microscope techniques were utilized to examine the adsorption of rhizobial cells to clover root hairs . Adsorption of cells of noninfective strains of Rhizobium trifolii or infective R . meliloti strains to clover root hairs was four to five times less than that of the infective R . trifolii strains . Attachment of the rod-shaped bacteria to clover root cells occurred in a polar, end-on fashion . Viable or heat-killed R . trifolii cells precoated with a clover lectin having 2-deoxyglucose specificity had increased adsorption to clover roots . Adsorption of bacteria to roots was not increased if the clover lectin was inactivated by heat or 2-deoxyglucose treatment prior to incubation with R . trifolii . Adsorption of R . trifolii to clover root hairs was inhibited by 2-deoxyglucose (30 mM) but not by 2-deoxygalactose or alpha-D-glucose . Adsorption of R . meliloti cells to alfalfa root hairs was not affected by 2-deoxyglucose at that concentration . These results suggest that expression of host specificity in the Rhizobium-clover symbiosis involves a preferential adsorption of infective cells to clover root hairs through a 2-deoxyglucose-sensitive receptor site.

Can J Microbiol, 1976 Jul, 22(7), 949 - 52
Reduction of acetylene by stationary cultures of free-living Rhizobium sp . under atmospheric oxygen levels; Evans WR et al.; The reduction of acetylene to ethylene by stationary (non-shaking) cultures of free-living rhizobia under atmospheric oxygen levels has been demonstrated . Under these conditions the development of the activity is inhibited by 10 mM NH4Cl and about 20% of oxygen is required for maximal activity . When the stationary cultures were shaken, oxygen concentrations of 1% and higher were found to be inhibitory . Specific activities of 20 and 40 nmol of acetylene reduced h-1 mg-1 protein were observed.

J Bacteriol, 1976 Jul, 127(1), 149 - 53
Oxygen requirement for acetylene reduction by pure cultures of rhizobia; Keister DL et al.; The oxygen and nutritional requirements for acetylene reduction by Rhizobium japonicum and Rhizobium sp . in liquid culture are described . The optimal oxygen concentration was about 0.1% in the gas phase, which is lower than that of any other known aerobic nitrogen-fixing microorganism . these organisms are also unique in that nitrogenase synthesis is not repressed in the presence of ammonium chloride under certain cultural conditions, in contrast to other wild-type bacteria.

Mikrobiologiia, 1976 JUL-AUG, 45(4), 704 - 9
{Competing ability of Rhizobium trifolii strains and efficiency of clover nitraginization on spent peat mosses}; Krylova LN et al.; The competing ability of active strains of clover nodule bacteria was assayed in vegetation and field experiments . The competing ability of the industrial strains 311a and 347a was found to be sufficiently high . These strains increased the yield of clover on exhausted turf peats of the Kirovsk Region by 26--29% . The stimulating effect was observed also with new strains 313b and 329b . The optimal dose for inoculation of clover seeds in these conditions is 50,000 nodule bacteria per one seed . Inoculation should be conducted by a strain with a high competing ability.

Appl Environ Microbiol, 1976 Jun, 31(6), 859 - 63
Improved method for preparing anaerobic bacteroid suspensions of Rhizobium leguminosarum for the acetylene reduction assay; Van Straten J et al.; A method using ethylenediaminetetraacetate (EDTA) and toluene-treated pea bacteroid suspensions for the acetylene reduction assay is described . The high level of acetylene reduction by these bacteroids is comparable to that of intact plants . Reproducibility of the EDTA-toluene treatment is, on the average, within 5% . Preliminary experiments with soybeans indicate that the EDTA-toluene method might be applicable to other legumes as well.

Arch Microbiol, 1976 May 3, 108(1), 45 - 54
Nitrogenase activity in cultured Rhizobium sp . strain 32H1: nutritional and physical considerations; Gibson AH et al.; Nutritional and physical conditions affecting nitrogenase activity in the strain of "cowpea" rhizobia, 32H1, were examined using cultures grown on agar medium . Arabinose in the basic medium (CS7) could be replaced by ribose, xylose, or glycerol, but mannitol, glucose, sucrose, or galactose only supported low nitrogenase (C2H2 reduction) activity . Succinate could be replaced by pyruvate, fumarate, malate, or 2-oxoglutarate, but without any carboxylic acid, nitrogenase activity was low or undetectable unless a high level of arabinose was provided . Inositol was not essential . Several nitrogen sources could replace glutamine including glutamate, urea, (NH4)2SO4 and asparagine . The maximum nitrogenase activity of cultures grown in air at 30 degrees C was observed under assay conditions of pO2=0.20-0.25 atm and 30 degrees C incubation . Greatest activity occurred after a period of rapid bacterial growth, when viable cell count was relatively constant . Compared with results obtained on the CS7 medium, nitrogenase activity could be substantially increased and/or sustained for longer periods of time by using 12.5 MM succinate and 100 mM arabinose, by increasing phosphate concentration from 2 to 30-50 mM, or by culturing the bacteria at 25 degrees C.

J Bacteriol, 1976 May, 126(2), 997 - 8
Genetic mapping of leucine and isoleucine-valine loci in Rhizobium japonicum; Doctor F et al.; Leucine and isoleucine-valine loci have been mapped in Rhizobium japonicum . Transformation analysis suggests a common pathway for isoleucine-valine biosynthesis . Three-point reciprocal crosses indicated that all the leucine loci are not genetically linked.

Biochem J, 1976 May 1, 155(2), 383 - 9
The molybdenum--iron protein of Klebsiella pneumoniae nitrogenase . Evidence for non-identical subunits from peptide 'mapping'; Kennedy C et al.; The molybdenum- and iron-containing protein components of nitrogenase purified from Klebsiella pneumoniae, Azotobacter vinelandii, Azotobacter chroococcum and Rhizobium japonicum bacteroids all gave either one or two protein-staining bands after sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, depending on the commercial brand of sodium dodecyl sulphate used . The single band obtained with K . pneumoniae Mo-Fe protein when some commercial brands of sodium dodecyl sulphate were used in the preparation of the electrode buffer was resolved into two bands by the addition of 0.01% (v/v) dodecanol to the buffer . Protein extracted from the two bands obtained after electrophoresis of K . pneumoniae Mo-Fe protein gave unique and distinct peptide 'maps' after tryptic digestion . Undissociated Mo-Fe protein contained both sets of tryptic peptides . These data are consistent with Mo-Fe protein from K . pneumoniae being composed of non-identical subunits . Amino acid analyses of the subunit proteins revealed some clear differences in amino acid content, but the two subunits showed close compositional relatedness, with a different index {Metzer, H., Shapiro, M.B., Mosiman, J.E . & Vinton, J.G . (1968) Nature (London) 219, 1166-1168} of 4.7.

J Histochem Cytochem, 1976 May, 24(5), 674 - 8
A phenomenon of photoenhancement of acridine orange-induced fluorescence; De DN et al.; It is a common experience that, with exposure to exciting radiation of the fluorescence microscope, the acridine orange-induced red fluorescence of the nucleus, produced by Feulgen hydrolysis, fades with a concomitant shift to green . The present investigation reports a phenomenon of photoenhancement observed in the hydrolyzed cytoplasm where pale green fluorescence increases in intensity with exposure to exciting radiation . The phenomenon has been noticed in Rhizobium, Oscillatoria, tomato root tip cells and human buccal epithelial cells . It is tentatively concluded that the gain in fluorescence yield is due to certain conformational changes of the acridine orange-protein complex induced by ultraviolet light flux.

J Bacteriol, 1976 Mar, 125(3), 1188 - 94
Immunofluorescent polar tips of Rhizobium japonicum: possible site of attachment or lectin binding; Bohlool BB et al.; Rhizobium japonicum USDA 31 demonstrated marked polarity by binding homologous fluorescent antibody (FA) heavily on one end of the cell . FA prepared against R . japonicum strains 110 and 138, and against R . trifolii TA1 cross-reacted with strain 31 only in the polar tip region . No polar immunofluorescing tips could be seen with FA against two other strains of R . japonicum or with those against several unrelated microorganisms . Common antigens localized only in a polar region were seen in many rhizobia stained with R . japonicum 31 FA: 22 of 23 strains of R . japonicum, 10 of 17 strains of R . trifolii, 3 of 7 strains of R . melitolii, 3 of 6 strains of R . phaseoli, and 3 of 9 strains of R . leguminosarum had some cells with detectable polar tips . The proportion of R . japonicum 31 cells with polar tips was high throughout the growth cycle . Polar tip staining was not affected by drastic cell treatments . A function was proposed for the polar tip region as a site for attachment . R . japonicum 31 cells attached to each other in a tip-to-tip fashion and endwise to fungal hyphae with the polar tip in contact with the hyphal wall . Binding of fluorescein isothiocyanate-labeled soybean lectin to certain strains of R . japonicum gave additional evidence of polarity . Polar binding of both antibody and lectin may provide insights into relationships between rhizobia and roots of host legumes.

Biochem J, 1976 Mar 1, 153(3), 597 - 606
The purification and properties of the glutamine synthetase from the cytosol of Soya-bean root nodules; McParland RH et al.; The major portion of glutamine synthetase activity in root nodules of soya-bean plants is associated with the cytosol rather than with Rhizobium japonicum bacteroids . Glutamine synthetase accounts for about 2% of the total soluble protein in nodule cytosol . Glutamine synthetase from nodule cytosol has been purified by a procedure involving fractionation with protamine sulphate, ammonium sulphate and polypropylene glycol, chromatography on DEAE-Bio-Gel A and Bio-Gel A-5m and affinity chromatography on glutamate-agarose columns . The purified preparation appeared to be homogeneous in the analytical ultracentrifuge . From sedimentation-equilibrium experiments a mol . wt . of about 376000 was determined for the native enzyme and 47300 for the enzyme in guanidinium chloride . From these data and measurements of electron micrographs, we have concluded that glutamine synthetase from nodule cytosol consists of eight subunits arranged in two sets of planar tetramers which form a cubical configuration with dimensions of about 10 nm (100 A) across each side . Glutamine synthetase from nodule cytosol has a higher glycine and proline content and a lower content of phenylalanine than the glutamine synthetase that has been prepared from pea seed . The cytosol enzyme contains four half-cystine molecules per subunit, which is in contrast with two reported for the enzyme from pea seed . Enzyme activity is striking influenced by the relative proportion of Mg2+ and Mn2+ in the assay medium . Activity is inhibited by feedback inhibitors and is influenced by energy charge.

Can J Microbiol, 1976 Feb, 22(2), 204 - 12
Morphology and host range of virulent phages of lotus rhizobia; Patel JJ; Nineteen virulent bacteriophages for fast- and slow-growing rhizobia were isolated . Most of the phage isolates were of two morphological types, and these showed specificity for either the fast- or the slow-growing rhizobia . The ecological distribution, morphology, and host range of the phages is presented . Classification of lotus rhizobia is discussed on the basis of phage typing.

Can J Microbiol, 1976 Feb, 22(2), 150 - 3
Glycerol metabolism in Rhizobium; Arias A et al.; Four strains of Rhizobium japonicum and one strain of R . trifolii were grown on glycerol and found to contain a soluble ATP-glycerol kinase and a particulate glycerolphosphate dehydrogenase . Both enzymes are induced by glycerol . The presence of NAD+-or NADP+-glycerol dehydrogenase was not detected in any of the strains . No significant differences were found in the glycerol metabolic pathway between fast-and slow-growing rhizobia.

Biochim Biophys Acta, 1976 Jan 20, 420(1), 105 - 11
A search for a leghaemoglobin-like compound in root nodules of Trema cannabina Lour; Coventry DR et al.; Root nodules collected from the non-leguminous plant Trema cannabina Lour . grown under natural field conditions were examined for the presence of leghaemoglobin . No trace of any soluble haemoglobin-like compound could be detected by spectrophotometric analysis or molecular weight comparison studies, although a small amount of soluble haemoprotein with peroxidase activity was isolated . Possible alternatives to the possession of a leghaemoglobin in non-legume/Rhizobium N2-fixing associations are discussed.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1976, 131(7), 665 - 70
Effect of phosphate fertilization and seed inoculation with ""Okadin'' at high rate on yield of broadbean and lentil; Badawy FH; The effect of phosphate fertilization and seed inoculation with ""Okadin'' preperation of rhizobia strains on the yield of broadbean and lentil was tested in field experiments during the seasons 1969 to 1972 in the farm of Faculty of Agriculture, Assiut University . Superphosphate was added at the rate of 0, 50, 100, or 200 kg/fa., and ""Okadin'' preparation, specific for the kind of legume planted, was applied to the seeds at 10 times the recommended rate . Application of superphosphate at any of the tested rates did not significantly affect total yield obtained, seeds yield, or the nitrogen content of seeds of lentil or braodbean . Seed inoculation with Okadin showed no significant effect on the yield of broadbean, but resulted in significant reduction in the yield of lentil seeds in the two seasons of the experiment.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1976, 131(3), 522 - 8
Effect of some pesticides on the efficiency of the inoculated Rhizobium associated with broad bean plants; Salem SH et al.; The effect of some pesticides on the efficiency of the inoculated rhizobium in broad bean plants (Vicia faba) was studied in greenhouse experiments . Different pesticides were used in this work, including insecticides, herbicides, nematocides, and a molecide in different concentrations . The study revealed the following conclusions . Application of insecticides in different concentrations generally affected the formation of efficient nodules on the root system of broad bean plants . The inhibitory effect was also reflected to some extent on the dry weight of the plants and total nitrogen fixed by rhizobia in association with the mentioned plants . Birlane (insecticide) was found to be the most inhibitory insecticide on the inoculated rhizobium . Some of the insecticides, such as Temik and Dursban, at lower concentration were found to be a stimulant to symbiotic N-fixation, giving higher amounts of nitrogen fixed in the macrosymbiont.

Mikrobiologiia, 1976 Jan-Feb, 45(1), 85 - 91
{The effect of nitrate and nitrite on the respiration and cytochrome system of Rhizobium lupini}; Romanov VI et al.; Differential spectrophotometry and oxygen electrode were used to study the effect of nitrate and nitrite on the cytochrome system and respiration of Rhizobium lupini cultivated in the conditions of different aeration, and bacteroids of this strain isolated from lupine nodules . In the anaerobic conditions, nitrate (10(-3) M) accepts electrons from the cytochrome system in suspensions of bacteroids and bacterial cells grown in the microaerophilic conditions (12 muM O2), but does not oxidize cytochromes of the cells cultivated in the aerobic conditions (240 muM 32) . Nitrate (10(-3) M) oxidizes actively only the cytochrome system of the cells grown in the microaerophilic conditions . Nitrite inhibits oxygen uptake by suspension of the bacteroids and pure culture of the cells; its necessary concentrations and the mode of action depend on the conditions of cultivation . Nitrite, like cyanide, blocks the terminal step in the cytochrome chain of Rh . lupini . Some properties of the cytochrome system are similar in the bacteroids and the bacterial culture grown in the conditions of oxygen deficiency.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1976, 131(3), 517 - 21
Effect of lindane on radio-carbon (14C) incorporation by Rhizobium japonicum; Balasubramanian A; Experiments conducted in vitro with three levels (1, 2, and 5 ppm active ingredient) of the insecticide lindane (gamma-BHC) showed no effect on the growth of Rhizobium japonicum, but altered the incorporation of radio-carbon (14C-glucose) into the different constituents of the growing cells . While all the three levels of the insecticide significantly depressed the incorporation of radiocarbon in the alcohol-extractable fraction, with no effect on the alcohol-ether soluble fraction of the cells, the 2 and 5 ppm levels enhanced the incorporation rate in the cold-TCA soluble fraction, but reduced it in the hot-TCA soluble fraction . Only with the 5ppm level of the insecticide treatment an increase in the specific activity of the insoluble protein fraction of the cells was observed . The results indicated that lindane, at various concentrations, affected the carbon (glucose) metabolism of the Rhizobium cells.

Acta Microbiol Pol, 1976, 25(2), 129 - 31
The effect of rhizobiophages on the effectiveness of Rhizobium meliloti in symbiosis with lucerne . II . Effects of phages on the R . meliloti strains during passing them through the plant; Sawicka A et al.; Studies were carried out of the effectiveness of Rhizobium meliloti strains reisolated from the roots of lucerne inoculated with effective and non-effective strains in the presence or absence of rhizobiophages . Estimates were made of the changes in phage-sensitivity and lysogeny found in these strains compared with the parent strains . It was found that the character of the reisolated strains depended on the changes brought about by passing through the plant and on the activity of the phages.

Acta Microbiol Pol, 1976, 25(2), 123 - 8
The effect of rhizobiophages on the effectiveness of Rhizobium meliloti in symbiosis with lucerne . I . Effect of various strains of R . meliloti and rhizobiophages on the yield and nitrogen fixation in lucerne; Sawicka A et al.; Pot and test-tube experiments were carried out on the effect of phages on yield and nitrogen fixation in lucerne inoculated with effective and non-effective strains of Rhizobium meliloti . It was found that some strains of R . meliloti became activated by the phages, which was reflected in an increase in yield and in crude protein content in the plants, while others lost their effectiveness . The results of pot experiments were in line with those of the test-tube experiments and have demonstrated that the effect of phages on the effectiveness of Rhizobium is not simply negative or positive, but depends on the properties of the bacterial strains used.

Antonie Van Leeuwenhoek, 1976, 42(4), 471 - 82
Purification and properties of an NADP+-specific isocitrate dehydrogenase from Rhizobium meliloti; Chandrasekharan Nambiar PT et al.; An NADP+-specific isocitrate dehydrogenase has been purified and characterized from Rhizobium meliloti . The enzyme showed Mn++ or Mg++ requirement . The apparent Km values were 2.00 x 10(-5) M and 1.51 x 10(-5) M for DL-isocitrate and NADP+, respectively . The enzyme was inhibited by ATP, to a lesser extent by ADP and AMP . alpha-Ketoglutarate also inhibited the enzyme activity . Oxalacetate and glyoxylate together inhibited the enzyme activity . The inhibition was competitive . Studies with thiol inhibitors suggested that the enzyme contained a sulfhydryl group at or near the active site . The enzyme has an approximate molecular weight of 60,000 . Fluorescence studies suggested that the enzyme contained tryptophan.

Biochim Biophys Acta, 1975 Dec 4, 414(2), 206 - 16
A comparison of DNA from free living and endosymbiotic Rhizobium leguminosarum (strain PRE); Reijnders L et al.; 1 . Bacteroids of Rhizobium leguminosarum (strain PRE) purified from root nodules of Pisum sativum (var . 'Rondo') by the standard procedure of differential centrifugation contained considerable contamination of mitochondrial material . This could be removed by incubation of the bacteroid preparation with 1 M KCl/1% deoxycholate . 2 . The DNA content of bacteroid cells of R . leguminosarum was found to have increased about three fold in comparison with the DNA content of free living R . leguminosarum bacteria . 3 . No significant difference in DNA composition of free living R . leguminosarum bacteria and bacteroids could be detected by CsCl equilibrium centrifugation, RNA - DNA hybridization and DNA - DNA reassociation studies.

J Gen Microbiol, 1975 Dec, 91(2), 345 - 54
Leghaemoglobin and the supply of O2 to nitrogen-fixing root nodule bacteroids: presence of two oxidase systems and ATP production at low free O2 concentration; Bergersen FJ et al.; Studies of rates of consumption of dissolved O2 by suspensions of bacteroids (Rhizobium japonicum, strain CB1809) from soybean root nodules showed the presence of two different terminal oxidase systems . A high-affinity system, sensitive to inhibition by N-phenylimidazole and by carbon monoxide, was most active when the dissolved O2 was between 0-01 and 0-1 muM . At 1 muM-O2 or higher, this oxidase system had little activity and O2 was consumed largely by a low-affinity system insensitive to these inhibitors . At low concentrations of dissolved O2, bacteroid respiration rates appeared to be diffusion-limited . When purified oxyleghaemoglobin was added to such systems, this restriction was relieved and respiration was maintained to much lower concentrations of free dissolved O2, where nitrogenase activity was greatest . Analysis of reactions which were terminated at various stages during the depletion of O2 from oxyleghaemoglobin showed that at low free O2 concentration, the high-affinity pathway produced up to five times greater bacteroid ATP concentrations than the low-affinity oxidase pathway operating about 1 muM free O2 in the absence of leghaemoglobin . At intermediate free O2 concentrations, occurring during the later stages of deoxygenation of oxymyoglobin, intermediate concentrations of ATP were found in the bacteroids.

Appl Microbiol, 1975 Dec, 30(6), 1003 - 9
Ultrastructure of Rhizobium-induced infection threads in clover root hairs; Napoli CA et al.; Ultrastructural studies of Rhizobium-induced infection threads in clover root hairs show that the infection thread is initiated by an invagination process . Root hair wall growth is redirected at a localized point, resulting in the formation of an open pore . There is no direct penetration through the wall, and the bacteria remain extracellular within the root hair.

Appl Microbiol, 1975 Dec, 30(6), 1017 - 33
Cross-reactive antigens and lectin as determinants of symbiotic specificity in the Rhizobium-clover association; Dazzo FB et al.; Cross-reactive antigens of clover roots and Rhizobium trifolii were detected on their cell surfaces by tube agglutination, immunofluorescent, and radioimmunoassay techniques . Anti-clover root antiserum had a higher agglutinating titer with infective strains of R . trifolii than with noninfective strains . The root antiserum previously adsorbed with noninfective R . trifolii cells remained reactive only with infective cells, including infective revertants . When adsorbed with infective cells, the root antiserum was reactive with neither infective nor noninfective cells . Other Rhizobium species incapable of infecting clover did not demonstrate surface antigens cross-reactive with clover . Radioimmunoassay indicated twice as much antigenic cross-reactivity of clover roots and R . trifolii 403 (infective) than R . trifolii Bart A (noninfective) . Immunofluorescence with anti-R . trifolii (infective) antiserum was detected on the exposed surface of the root epidermal cells and diminished at the root meristem . The immunofluorescent crossreaction on clover roots was totally removed by adsorption of anti-R . trifolii (infective) antiserum with encapsulated infective cells but not with noninfective cells . The cross-reactive capsular antigens from R . trifolii strains were extracted and purified . The ability of these antigens to induce clover root hair deformation was much greater when they were obtained from the infective than noninfective strains . The cross-reactive capsular antigen of R . trifolii 403 was characterized as a high-molecular-weight (greater than 4.6 times 10(6) daltons), beta-linked, acidic heteropolysaccharide containing 2-deoxyglucose, galactose, glucose, and glucuronic acid . A soluble, nondialyzable, substance (clover lectin) capable of binding to the cross-reactive antigen and agglutinating only infective cells of R . trifolii was extracted from white clover seeds . This lectin was sensitive to heat, Pronase, and trypsin . inhibition studies indicated that 2-deoxyglucose was the most probable haptenic determinant of the cross-reactive capsular antigen capable of binding to the root antiserum and the clover lectin . A model is proposed suggesting the preferential adsorption of infective versus noninfective cells of R . trifolii on the surface of clover roots by a cross-bridging of their common surface antigens with a multivalent clover lectin.

J Gen Microbiol, 1975 Dec, 91(2), 403 - 13
Properties of some bacteriocins produced by Rhizobium trifolii; Schwinghamer EA; Bacteriocins produced by six strains of Rhizobium trifolii were found to be of the relatively low molecular weight, non-phage type . The molecular weights ranged from approximately 1-8 X 105 to 2-0 X 105 . All were of protein composition, as indicated by buoyant density (1-32 to 1-34 g/cm3) in CsC1 and by sensitivity to proteolytic enzymes . They were resistant to RNAase but sensitive to DNAase . The six bacteriocins could further be separated into two subgroups on the basis of sensitivity to extremes of pH, binding to filter membranes, activity spectrum on sensitive strains of R . trifolii, and possibly mode of action on sensitive bacteria . Bacteriocin production occurred spontaneously during the early-to mid-exponential phase of bacterial growth in broth culture.

Arch Microbiol, 1975 Sep 30, 105(1), 27 - 32
Adsorption and selection of rhizobia with ion-exchange papers; Werner D et al.; Ion exchange papers were used to study the adsorption of 32P-labelled rhizobia on defined surfaces . Two strains of Rhizobium japonicum and one each of R . leguminosarum and R . lupini were compared with Escherichia coli and Bacillus subtilis . The ratio of adsorption to strong and to weak acid papers/strong and weak basic papers was consistantly higher for all rhizobial strains compared to the other bacteria . The process of desorption by increasing the ion-concentration causes about 35% desorption between 0.02 and 0.1 M MgCl2, however, an increase to 1 M does not desorb more labelled Rhizobium japonicum or E . coli cells . The ratio of adsorbed cpm to colony formers, desorbed by 0.1 M NaCl was similar with Rhizobium japonicum for all six ion exchange papers . For E . coli this ratio varied widely for the different papers . The selection of Rhizobium against a more closely related bacterium by this adsorption/desorption procedure was demonstrated with mixed cultures of Rhizobium japonicum and Chromobacterium violaceum giving a more than 80 fold enrichment of the former . Rhizobium japonicum cells, ad/desorbed from all ion exchange papers kept their infectivity and formed nodules on Glycine max with an activity of 20-40 nM C2H4-hr(-1)-mg nodule(-1) . A desorption of Rhizobium japonicum from soybean roots also occurred by increasing the ion concentration . 2-3 times as many cells were removed in this way compared to washing with water.

Mikrobiologiia, 1975 Sep-Oct, 44(5), 820 - 4
{Synthesis and breakdown of poly-beta-hydroxybutyric acid in Rhizobium lupini}; Romanov VI et al.; The effect of various substrates on synthesis and decomposition of poly-beta-hydroxybutyric acid (PHBA) was studied in cell suspensions of the effective strain of Rhizobium lupini and in suspensions of the bacteroids of this strain which were isolated from lupine nodules at different growth stages of the plants . Glucose and beta-hydroxybutyrate were found to be the best substrates for synthesis of PHBA in all variants . The content of PHBA in the presence of these substrates increased in suspensions by 2.0 to 2.5 times during ten hours of incubation . In the presence of succinate, PHBA was actively synthesized only by the bacteroids isolated during the stage of active nitrogen fixation (flowering of the plants) . In the absence of exogenous substrates, PHBA was decomposed, especially if ammonium ions were present in suspensions . No synthesis of PHBA was registered in the presence of ammonium and glucose, and the rate of PHBA decomposition was high in this case during the stage of active nitrogen fixation.

J Gen Microbiol, 1975 Sep, 90(1), 69 - 75
Inhibition of protein synthesis by D-threo-chloramphenicol in the laboratory and nodule forms of Rhizobium lupini; Coventry DR et al.; Protein synthesis by both laboratory-grown bacteria and isolated nodule bacteroids of Rhizobium lupini (strain WU8) is inhibited by D-threo-chloramphenicol, the bacteroid form being the more sensitive to the antibiotic . A comparison between the two forms of the uptake of {14C}chloramphenicol showed that the bacteria always attained a lower intracellular chloramphenicol concentration . It is proposed that the sensitivity difference is due to a difference in membrane permeability between the two forms.

J Bacteriol, 1975 Sep, 123(3), 1265 - 8
Acetylene reduction by pure cultures of Rhizobia; Keister DL; Acetylene reduction has been demonstrated in pure cultures of rhizobia . The requirements and conditions necessary for the activity in Rhizobium sp . 32H1 are described . The most important factors are a low cell density and a very low oxygen concentration.

Z Naturforsch {C}, 1975 Sep-Oct, 30(5), 687 - 8
Nitrogen fixing activity in Rhizobium japonicum separated from plant cell cultures; Werner D et al.; Induced by soy bean tissue cultures in socalled "tissue chambers", Rhizobium japonicum str . 61-A-96 developed nitrogenase activity separated from the plant cells . The activity proceded for 48 h with a rate of 1 X 10(-8) nmol C2H4h-1 cell-1, which is about 6% of the activity measured for bacteroids from Rhizobium japonicum in nodules of Glycine max.

Carbohydr Res, 1975 Aug, 43(1), 145 - 9
Fragmentation analysis of extracellular acid polysaccharides from seven Rhizobium strains . Part I . D-glucuronic acid-containing oligosaccharides; Somme R; The extracellular, bacterial polysaccharides from seven Rhizobium strains have been submitted to partial hydrolysis with acid . Several neutral oligosaccharides, some containing pyruvic acid, were isolated together with D-glucuronic acid-containing oligosaccharides . The polysaccharide from Rh . meliloti did not contain glucuronic acid . For the other six strains, the following components were characterized: 4-O-(beta-D-glucopyranosyluronic acid)-D-glucuronic acid, 4-O-(beta-D-glucopyranosyluronic acid)-D-glucose, and O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-D-glucose . These results indicate the presence of chains containing two beta-(1leads to4)-linked D-glucuronic acid residues, beta-linked to D-glucose at position 4.

Can J Microbiol, 1975 Aug, 21(8), 1254 - 8
Role of pectic and cellulolytic enzymes in the invasion of the soybean by Rhizobium japonicum; Hunter WJ et al.; Past workers have suggested pectic enzyme involvement in the invasion of legumes by Rhizobium . However, no role for pectic acid, pectin, or methyl cellulose depolymerase enzymes in the invasion of R . japonicum was suggested by the current study . Seedling inoculation with infective bacteria did not result in increased enzyme activity . Rhizobium japonicum cell-free culture extracts and 3-indoleacetic acid did not affect the activation, induction, or binding of these enzymes.

Appl Microbiol, 1975 Aug, 30(2), 172 - 7
Antigenic differences between infective and noninfective strains of Rhizobium trifolii; Dazzo FB et al.; Immunodiffusion and immunoelectrophoresis techniques have revealed the presence of soluble antigens in sonicated preparations of four infective strains of Rhizobium trifolii which were absent in similar preparations of related noninfective mutants derived from the infective strains . The soluble antigens unique to the infective strains were cross-reactive with one another.

Biochim Biophys Acta, 1975 Jul 27, 397(1), 24 - 35
Nitrate reductase from bacteroides of Rhizobium japonicum: enzyme characteristics and possible interaction with nitrogen fixation; Kennedy IR et al.; The soluble nitrate reductase of Rhizobium japonicum bacteroids has been purified and its properties compared to those of aerobically grown cells . The enzymes from both sources are similar with molecular weights of about 70 000 suggesting no close relationship with the molybdo-protein component of nitrogenase . Nitrite, the product of nitrate reductase, strongly inhibited the nitrogenase activity from bacteroids, at concentrations less than 100 muM . Thus, an interference in the rate of nitrogen fixation is possible as a result of nitrate reductase activity . A study of the distribution of nitrate reductase in bacteroids indicates that a proportion of the total activity is membrane-bound but that this activity is similar to that in the soluble fraction . Purified nitrate reductase required reduced viologen dyes for activity . Neither NADPH or NADH or FAD could substitute as electron donors . Dithionite is a strong inhibitor and inactivated nitrate reductase from all sources examined . This inactivation is prevented by methyl viologen . Purified nitrate reductase from bacteroids and bacteria Rhizobium japonicum is practically unaffected by exposure to oxygen.

Ann Microbiol (Paris), 1975 Jul-Aug, 126B(1), 3 - 15
{A study of polysaccharides in fast growing "Rhizobium" (author's transl)}; Courtois B et al.; This work is an attempt to use the composition of exopolysaccharides in the Rhizobium genus as a criterium of taxonomic importance . The organisms were first cultured in media and under conditions which led to the production of as many polysaccharides as possible . The medium chosen for proliferation conditions was Wright's medium; for conditions of non-proliferation conditions was Wright's medium; for conditions of non-proliferation, a minimal medium without nitrogen was used . The polysaccharides synthesised in Wright's medium consists in neutral sugars such as glucose, galactose, mannose and sometimes rhamnose and in uronic acid in various quantities . If no mannose is found in the polysaccharides when they are synthesised in non-proliferation conditions and if mannans are found in yeast broth, it may be thought, as suggested by Humphrey, that mannose would come from those mannans . The study of the composition of these polysaccharides enables us to sort out two groups of fast growing Rhizobium . The first one, relatively uniform, corresponds to the strains of R . leguminosarum, trifolii and phaseoli . In these strains, the polysaccharides are made of about 70% of neutral sugars and 20% of glucuronic acid.

Appl Microbiol, 1975 Jul, 30(1), 123 - 31
Production of cellulose microfibrils by Rhizobium; Napoli C et al.; Electron microscope examination of Rhizobium spp . revealed microfibrils produced by flocculating strains but not by nonflocculating strains . The microfibrils from R . trifolii (NA30) were isolated and identified as cellulose by enzymatic, X-ray diffraction, and infrared spectral analyses . Both infective and noninfective strains of R . trifolii flocculated and produced microfibrils . More infection threads were observed in clover root hairs growing in the presence of flocs in comparison with root hairs where single bacterial cells predominated.

Can J Microbiol, 1975 Jul, 21(7), 1009 - 12
Enzymes of ammonia assimilation in Rhizobium leguminosarum bacteroids; Kurz WG et al.; The activities of the following enzymes were studied in connection with dinitrogen fixation in pea bacteroids: glutamine synthetase(L-glutamate: ammonia ligase (ADP-forming)(EC 6.3.1.2)(GS); glutamate dehydrogenase (NADP+)(L-glutamate: NADP+ oxidoreductase (deaminating)(EC 1.4.1.4)(GDH); glutamate synthase (L-glutamine: 2-exeglutarate aminotransferase (NADPH-oxidizing))(EC 2.6.1.53)(GOGAT) . GS activity was high throughout the growth of the plant and GOGAT activity was always low . It is unlikely that GDH or the GS-GOGAT pathway can account for the incorporation of ammonia from dinitrogen fixation in the pea bacteroid,

Arch Microbiol, 1975 Jun 22, 104(2), 171 - 8
Electron microscopic characterization of Rhizobium bacteriophage 16-6-12 and its isolated deoxyribonucleic acid; Lurz R et al.; Bacteriophage 16-6-12 of Rhizobium lupini has a long, non-contractile tail and a head which is hexagonal in outline . The tail is 140 nm in length, 11 nm in diameter, and carries a short term fiber . Analysis of the tail structure by optical diffraction indicates that it is of the helical "stacked disc" type . After phenol-extraction from purified particles, the DNA of phage 16-6-12 can circularize in vitro . No significant difference in contour length was observed between the linear (14.34 plus or minus 0.28 mum) and circular (14.44 plus or minus 0.24 mum) forms of molecules . After partial denaturation with alkali an AT-GC-map was constructed, which shows an asymmetric distribution of AT- and GC-rich regions . It is concluded that this phage DNA can circularize due to the presence of cohesive ends and that it is not circularly permuted.

Biochim Biophys Acta, 1975 Jun 17, 387(3), 461 - 74
Involvement of oxyleghaemoglobin and cytochrome P-450 in an efficient oxidative phosphorylation pathway which supports nitrogen fixation in Rhizobium; Appleby CA et al.; Cellular ATP level, ATP/ADP ratio and nitrogenase activity rise when oxyleghaemoglobin is added to respiring suspensions of Rhizobium japonicum bacteroids from soybean root nodules . Increased gaseous O2 tension is much less efficient than oxyleghaemoglobin in stimulation of bacteroid ATP production . Studies with the inhibitor carbonyl cyanide m-chlorophenylhydrazone show this ATP to be generated as a consequence of oxidative phosphorylation . N-Phenylimidazole, a specific cytochrome P-450 inhibitor, also lowers the efficiency of bacteroid oxidative phosphorylation . An approximately linear relationship is observed between ATP/ADP ratio and nitrogenase activity as N-phenylimidazole concentration is lowered . It is suggested that cytochrome P-450 is a component of the leghaemoglobin-facilitated respiration pathway and that it may act as intracellular O2 carrier rather than terminal oxidase . A less efficient oxidase appears to function when cytochrome P-450 is inhibited.

J Gen Virol, 1975 Jun, 27(3), 379 - 83
Isolation and characterization of a rod-shaped bacteriocin from a strain of Rhizobium; Gissmann L et al.; A bactericidal agent ('bacteriocin 16-2') produced by rhizobial strain 16-2 had been characterized as a sheathless rod-shaped particle with a length of 200 nm and a diam . of 8 nm . One end of the rod is pointed and carries short fibre-like appendages, while the other end appears square . The particles specifically adsorb with their pointed end to bacteriocin-sensitive, but not to bacteriocin-resistant, cells . The possible mode of action of this bacteriocin in discussed.

Can J Microbiol, 1975 Jun, 21(6), 884 - 95
Protozoa and the decline of Rhizobium populations added to soil; Danso SK et al.; A fall in Rhizobium abundance occurred in nonsterile soil inoculated with large numbers of the root-nodule bacteria, but many of the rhizobia still survived . No such decline was evident in sterile soil . Protozoa feeding on these bacteria were isolated from soil and other environments . As the abundance of Rhizobium meliloti and a cowpea Rhizobium strain in soil decreased, the protozoan density increased . The inability of the predators to eliminate their prey from soil was not the result of the presence of organisms feeding on the protozoa because many rhizobia survived in sterile soil inoculated with the prey and cultures of individual protozoa, nor was it the result of the rapid multiplication of the bacteria to replace those consumed because survivors were still numerous in essentially organic matter free soil in which the bacteria did not grow appreciably . The lack of elimination also was not associated with a protective effect of soil particles because survivors were still abundant in solutions inoculated with protozoa and bacteria . It is suggested that the size of the prey population diminishes until a density is attained at which the energy used by the predator in hunting for the survivors equals that obtained from the feeding.

Biochim Biophys Acta, 1975 May 23, 391(1), 9 - 14
Effect of adenine nucleotides on NAD-dependent isocitrate dehydrogenases in rhizobia and bacteroids of legume root nodules; Moustafa E et al.; ATP, ADP, AMP and cyclic AMP inhibit NAD-dependent isocitrate dehydrogenase (L-s-isocitrate : NAD-+ oxidoreductase, EC 1.1.1.41) from rhizobia but have no effect on the enzyme from corresponding bacteroids . This was observed using three rhizobial strains two of which are effective, and one ineffective, with Lotus pedunculatus . Using partially purified enzyme from each of the three rhizobial strains it was found that the adenine nucleotides inhibit the enzyme by competing with NAD-+, not with isocritrate . The rate of reaction catalysed by the enzyme (expressed as activity per mg protein) in cell-free extracts of each of the effective rhizobial strains was about three times that of the reaction in extracts of the corresponding bacteroids . No correlation was found between effectiveness and NAD-dependent isocitrate dehydrogenase activity in the rhizobial cells.

J Bacteriol, 1975 May, 122(2), 691 - 4
Structural similarity of the membrane envelopes of rhizobial bacteroids and the host plasma membrane as revealed by freeze-fracturing; Tu JC; The freeze-fracture technique was used to study the host plasma membrane and the membrane envelope of bacteroids in rhizobial root nodules of three host-rhizobium combinations . In all three combinations studied, the membrane envelopes of bacteroids are structurally similar to their host plasma membrane . However, the membrane appears to be reversed, because the number and arrangement of particles in the outer fractured face (face A, concave) and in the inner fractured face (face B, convex) of the host plasma membrane are seen, respectively, in the inner fractured face (face B, convex) and in the outer fractured face (face A, concave) of the membrane envelope of the bacteroids at an early stage . This reversion of the membrane surface is consistent with the hypothesis that the membrane envelopes of bacteroids are derived from the host plasma membrane during endocytotic engulfment.

C R Acad Sci Hebd Seances Acad Sci D, 1975 Apr 28, 280(16), 1911 - 4
{Symbiotic efficiency in spontaneous mutants of Rhizobium legumino-sarum resistant to streptomyocin, spectinomycin, or kanamycin}; Amarger N; Symbiotic effectiveness of 45 mutant strains selected from four wild effective strains of Rhizobium leguminosarum for resistance to streptomycin, spectinomycin or kanamycin was determined on Vicia faba . Loss of effectiveness occurred in twenty of these mutants; distribution of ineffective mutants was uniform among the three types of antibiotic resistant mutants but varied with the parent strain from which mutants have been derived.

Arch Microbiol, 1975 Apr 7, 103(2), 151 - 4
Loss of agglutinating specificity in stock cultures of Rhizobium meliloti; Wilson MH et al.; Several strains of Rhizobium meliloti which have been subcultured for 23-33 years have changed from being markedly specific in their somatic agglutination reactions to become widely cross-reactive . On the other hand a fresh collection of the same species obtained from naturally nodulated, field-grown plants revealed the high degree of agglutinating specificity which had previously characterised the old cultures . Attempts to reselect a specific substrain from old cross-agglutinating cultures by six plant passages, or to detect change to cross reactivity by ten successive subcultures of recent isolates were unsuccessful . However, one strain, isolated in 1939, was recently found to contain both specific and cross-reactive substrains . Practically all the cultures, both old and recent, showed considerable mutability in colony characteristics but none of these was consistently correlated with cross agglutinability . Instability in 6.4% (w/v) NaCl was characteristic of the cross-agglutinating cultures . Cross reactivity was associated with a shared lipopolysaccharide antigen (LPS) which appeared to be obscured by an outer antigen in most strains still showing specific agglutinability . In the exceptional case of strain SU27, agglutination could be attributed to its specific LPS.

Appl Microbiol, 1975 Apr, 29(4), 515 - 21
Regulation of predation by prey density: the protozoan-Rhizobium relationship; Danso SK et al.; Tetramitus rostratus and strains of Hartmanella, Naegleria, and Vahlkampfia consumed large numbers of Rhizobium meliloti cells in a salt solution, but protozoan multiplication and the bacterial decline stopped when the prey density fell to about 10-6 to 10-7 cells/ml . At higher prey densities, the maximum numbers of Hartmanella sp . and Naegleria sp . were proportional to the quantity of R . meliloti initially provided to the amoebas . When supplemental rhizobia were supplied to Hartmanella sp . or Naegleria sp . after their active feeding had terminated, presumably because the remaining 10-6 or 10-7 bacteria/ml could not be captured, replication of the protozoa was initiated . The rate of elimination of rhizobia present in large populations was proportional to the initial abundance of Naegleria sp., but the final numbers of amoebas and surviving R . meliloti cells were independent of initial numbers of predators . The surviving bacteria were not intrinsically resistant to attack because 98% of the survivors, when concentrated, were consumed . It is suggested that large populations of bacteria in nature may be reduced in size by predatory protozoa, but many of the prey cells will not be eliminated.

J Gen Microbiol, 1975 Apr, 87(2), 343 - 50
Identification of the rhizobium strains in pea root nodules using genetic markers; Johnston AW et al.; Pea plants were inoculated jointly with pairs of genetically marked strains of Rhizobium leguminosarum . Out of 297 modules examined 56 contained both inoculant strains . The ratios of the strains in the inoculum did not affect the frequencies of mixed nodules . Generally one of the strains consistently occupied the majority of the nodules and ithe mixed nodules comprised the majority of bacteria . Transfer of the P-group R factor, RP4, between certain strains of Rhizobium within mixed nodules was detected . In some cases the non-parental progeny comprised 10% of the rhizobia isolated from such nodules.

Prikl Biokhim Mikrobiol, 1975 Mar-Apr, 11(2), 203 - 6
{Effect of cultivation conditions on the accumulation of poly-beta-hydroxy-butyric acid in Rhizobium lupini}; Yushkova LA et al.; The influence of the age of the culture and nitrogen source on the accumulation of poly-beta-hydroxybutyric acid by different strains of Rhizobium lupini was studied . The accumulation depended on the age of the culture and reached maximum at the end of the logarithmic and at the beginning of the stationary phase of the bacterial growth (about 50-60% dry weight) . The accumulation varied in relation to the nitrogen source used: it was the highest in the glutamate medium and the lowest on nitrate nitrogen; the culture grown on ammonium phosphate was intermediate.

Lipids, 1975 Mar, 10(3), 134 - 9
Some unusual fatty acids of Rhizobium; Gerson T et al.; A number of unusual fatty acids were identified after isolation from Rhizobium . They include 11-methyl-octadec-11-enoic, 12-methoxy-11-methyl- and 11-methoxy-12-methyloctadecanoic, and 11-methoxy- and 13-methoxynonadecanoic acids.

Biochim Biophys Acta, 1975 Feb 13, 381(2), 248 - 56
Immunological evidence for the capability of free-living Rhizobium japonicum to synthesize a portion of a nitrogenase component; Bishop PE et al.; Immunodiffusion tests conducted under aerobic conditions demonstrated that cross-reactive material to antiserum prepared against the Mo-Fe protein component of nitrogenase from soybean nodule bacteroids was detectable in extracts of free-living Rhizobium japonicum cells cultured in a standard medium under: aerobic conditions; aerobic conditions with nitrate; aerobic conditions with ammonia; anaerobic conditions with nitrate; and anaerobic conditions with nitrate and ammonia . The most intense precipitin bands resulted from cross-reaction of the antiserum with extracts of cells cultured anaerobically with nitrate or anaerobically with ammonia and nitrate . Immunodiffusion experiments with crude bacteroid extract and purified Mo-Fe protein revealed a greater number of precipitin bands in tests conducted under aerobic conditions than those conducted under anaerobic conditions . These results indicate that some of the cross-reactive material observed under aerobic conditions resulted from breakdown of the Mo-Fe protein . Bacteroid extracts of nodules from plants supplied with ammonia exhibited only a trace of nitrogenase activity . The addition of an excess of the Fe protein component of nitrogenase, however, resulted in 270-fold enhancement of activity indication the presence of active Mo-Fe protein in these extracts . Our experiments together with results published elsewhere provide evidence that the genetic information for synthesis of a part of the Mo-Fe component of nitrogenase is carried by Rhizobium.

Can J Microbiol, 1975 Feb, 21(2), 196 - 204
Conversion of spheroplast symbiotes in a leafhopper, Helochara communis Fitch (Cicadellidae: Homoptera); Chang KP et al.; In mycetomes of leafhoppers, Helochara communis, ultrastructural and histochemical studies revealed that spheroplast symbiotes (t-symbiotes) were converted to 'a-symbiotes' (so-called), with apparent loss of DNA--a phenomenon reminiscent of rhizobium-bacteroid conversion in certain legume nodules . Additional t-symbiotes were incorporated into the substance of these 'a-symbiotes'.

Acta Biol, 1975, 26(1-2), 1 - 7
Insecticides and soil microorganisms . III . Fate of 14C-labelled Dipterex as affected by two nodule-forming rhizobium spp . and roots of their respective leguminous host plants; Salama AM et al.; Chromatographic analysis led to the identification of monomethyl- and dimethyl-phosphates as metabolites resulting from the enzymatic degradation of 14C-labelled Dipterex in the buffer solutions and root tissues of broad bean and clover plants, as well as in the culture media of rhizobium leguminosarum and Rhizobium trifolii . The formation of 14CO2 from rhizobial cultures containing radioactive Dipterex suggests that some of the liberated methanol groups (during breakdown of Dipterex) are oxidatively degraded by the two Rhizobium spp.

Acta Microbiol Pol A, 1975, 8(3), 151 - 60
Frequency of infection and efficiency of transfection of Rhizobium meliloti cells and spheroplasts; Staniewski R et al.; Competent cultures of Rhizobium meliloti cells and spheroplasts obtained by various methods were infected with DNA of phage 1A . The Frequency of infection among the cells and spheroplasts was 2 X 10(-8)-5 X 10(-10) . The efficiency of transfection calculated from the ratio of plaque forming units to infective DNA molecule of phage 1A was 5 X 10(-8) to 10(-10) . Frequency of infection and efficiency of transfection among the competent cells were by one order of magnitude higher in the case of the spheroplasts . The use of various media did not noticeably alter the efficiency of transfection.

Acta Microbiol Pol A, 1975, 7(4), 181 - 8
Studies on phage 1P receptors in Rhizobium trifolii and Rhizobium leguminosarum; Zajac E et al.; The rate of phage 1P attachment to Rhizobium cell walls was increased in the presence of ethylenediaminetetraacetic acid (EDTA) . On the other hand the rate of adsorption of phage 1P to the Triton -- insoluble cell walls was diminished . The subsequent treatment of cell walls with 2% Triton X-100 and 5mM EDTA caused a more substantial decline of the phage inactivating capacity . Lipopolysaccharides (LPS) isolated from the sensitive strains, contrary to those from phage-resistant mutants, inactivated effectively phage 1P . The content of sugars in LPS preparations was determined by using gas liquid chromatography.

J Gen Microbiol, 1975 Jan, 86(1), 39 - 48
Ammonia assimilation by rhizobium cultures and bacteroids; Brown CM et al.; The enzymes involved in the assimilation of ammonia by free-living cultures of Rhizobium spp . are glutamine synthetase (EC . 6.o.I.2), glutamate synthase (L-glutamine:2-oxoglutarate amino transferase) and glutamate dehydrogenase (ED I.4.I.4) . Under conditions of ammonia or nitrate limitation in a chemostat the assimilation of ammonia by cultures of R . leguminosarum, R . trifolii and R . japonicum proceeded via glutamine synthetase and glutamate synthase . Under glucose limitation and with an excess of inorganic nitrogen, ammonia was assimilated via glutamate dehydrogenase, neither glutamine synthetase nor glutamate synthase activities being detected in extracts . The coenzyme specificity of glutamate synthase varied according to species, being linked to NADP for the fast-growing R . leguminosarum, R . melitoti, R . phaseoli and R . trifolii but to NAD for the slow-growing R . japonicum and R . lupini . Glutamine synthetase, glutamate synthase and glutamate dehydrogenase activities were assayed in sonicated bacteroid preparations and in the nodule supernatants of Glycine max, Vicia faba, Pisum sativum, Lupinus luteus, Medicago sativa, Phaseolus coccineus and P . vulgaris nodules . All bacteroid preparations, except those from M . sativa and P . coccineus, contained glutamate synthase but substantial activities were found only in Glycine max and Lupinus luteus . The glutamine synthetase activities of bacteroids were low, although high activities were found in all the nodule supernatants . Glutamate dehydrogenase activity was present in all bacteroid samples examined . There was no evidence for the operation of the glutamine synthetase/glutamate synthase system in ammonia assimilation in root nodules, suggesting that ammonia produced by nitrogen fixation in the bacteroid is assimilated by enzymes of the plant system.

Folia Microbiol (Praha), 1975, 20(5), 412 - 7
Fructose 1,6-bisphosphate aldolase activity of Rhizobium species; Siddiqui KA et al.; FDP aldolase was found to be present in the cell-free extracts of Rhizobium leguminosarum, Rhizobium phaseoli, Rhizobium trifolii, Rhizobium meliloti, Rhizobium lupini, Rhizobium japonicum and Rhizobium species from Arachis hypogaea and Sesbania cannabina . The enzyme in 3 representative species has optimal activity at pH 8.4 in 0.2M veronal buffer . The enzyme activity was completely lost by treatment at 60 degrees C for 15 min . The Km values were in the range from 2.38 to 4.55 X 10(-6)M FDP . Metal chelating agents inhibited enzyme activity, but monovalent or bivalent metal ions failed to stimulate the activity . Bivalent metal ions in general were rather inhibitory.

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