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 th