Pediatr Infect Dis J, 1992 Jul, 11(7), 547 - 53 Pseudomonas infections in children with human immunodeficiency virus infection; Roilides E et al.; Thirteen bacteremias and 25 nonbacteremic infections caused by Pseudomonas spp . occurred in 22 of 236 children with human immunodeficiency virus infection with a rate of infection of 0.098 (bacteremia, 0.030) per patient year . Four patients were neutropenic (less than 500/microliters) . Central venous catheter (CVC)-related infections were most frequent (n = 20) followed by otitis externa (n = 6) and pneumonia (n = 5) . Pseudomonas aeruginosa was the most common isolate and caused both CVC-related and CVC-unrelated infections, whereas other Pseudomonas spp . and Xanthomonas maltophilia were almost exclusively associated with CVC-related infections . The children who received appropriate therapy had a favorable outcome . In 7 CVC-related infections (35%) the catheter was removed . Pseudomonas spp . are of increasing importance in human immunodeficiency virus-infected children causing significant morbidity and increased hospitalization . These infections may be life-threatening if appropriate therapy is not vigorously initiated. Appl Environ Microbiol, 1992 Jul, 58(7), 2188 - 95 Assessment of genetic diversity and population structure of Xanthomonas oryzae pv . oryzae with a repetitive DNA element; Leach JE et al.; A repetitive DNA element cloned from Xanthomonas oryzae pv . oryzae was used to assess the population structure and genetic diversity of 98 strains of X . oryzae pv . oryzae collected between 1972 and 1988 from the Philippine Islands . Genomic DNA from X . oryzae pv . oryzae was digested with EcoRI and analyzed for restriction fragment length polymorphisms (RFLPs) with repetitive DNA element as a probe . Twenty-seven RFLP types were identified; there was no overlap of RFLP types among the six races from the Philippines . Most variability (20 RFLP types) was found in strains of races 1, 2, and 3, which were isolated from tropical lowland areas . Four RFLP types (all race 5) were found among strains isolated from cultivars grown in the temperate highlands . The genetic diversity of the total population of X . oryzae pv . oryzae was 0.93, of which 42% was due to genetic differentiation between races . The genetic diversities of strains collected in 1972 to 1976, 1977 to 1981, and 1982 to 1986, were 0.89, 0.90, and 0.92, respectively, suggesting a consistently high level of variability in the pathogen population over the past 15 years . Cluster analysis based on RFLP banding patterns showed five groupings at 85% similarity . The majority of strains from a given race were contained within one cluster, except for race 3 strains, which were distributed in three of the five clusters. Lett Appl Microbiol, 1992 Jun, 14(6), 233 - 7 Effect of parB on plasmid stability and gene expression in Xanthomonas campestris; Pimenta Ade L et al.; The stabilization locus parB was subcloned into the broad host range plasmid pAP2, which contains the alpha-amylase gene from Bacillus subtilis, and introduced into Xanthomonas campestris pv campestris and X.c.pv manihotis . Analysis of the stability of plasmid pAP2 (parB-) and pAP23 (parB+) showed that the parB locus decreased significantly the plasmid loss rate mainly by X.c.pv campestris . The lower efficiency of stabilization in X.c.pv manihotis was probably due to the incompatibility system between the native plasmids and the newly introduced pAP23 . Although parB had conferred higher stability, it determined a lower rate of alpha-amylase activity even by the strain Cm where its stabilization rate was higher. J Hosp Infect, 1992 Jun, 21(2), 103 - 10 Microbial contamination of brushes used for preoperative shaving; Oie S et al.; Microbial contamination of brushes used for preoperative shaving was investigated . Of the 24 brushed examined, 18 were contaminated with 10(6)-10(9) colony forming units (cfu) per brush . Non-fermentative Gram-negative bacilli such as Pseudomonas aeruginosa and Xanthomonas maltophilia, and yeast-like fungi such as Candida parapsilosis were the primary contaminants . The mean bacterial count on the skin after the use of contaminated brushes (having a mean bacterial count 2.2 x 10(8) cfu) in 14 subjects was 4.6 x 10(5) cfu 25 cm-2, which was about 100 times (p less than 0.001) the control level . Contaminated brushes could not be disinfected with 80% ethyl alcohol, 0.1% sodium hypochlorite or 0.5% chlorhexidine . These findings suggest that the use of brushes should be avoided for preoperative shaving with a razor, and that sterile gauze and shaving foam should be used instead of a brush and soap. Mol Plant Microbe Interact, 1992 May-Jun, 5(3), 204 - 13 An Xanthomonas citri pathogenicity gene, pthA, pleiotropically encodes gratuitous avirulence on nonhosts; Swarup S et al.; The pathogenicity gene, pthA, of Xanthomonas citri is required to elicit symptoms of Asiatic citrus canker disease; introduction of pthA into Xanthomonas strains that are mildly pathogenic or opportunistic on citrus confers the ability to induce cankers on citrus (S . Swarup, R . De Feyter, R . H . Brlansky, and D . W . Gabriel, Phytopathology 81:802-809, 1991) . The structure and the function of pthA in other xanthomonads and in X . citri were further investigated . When pthA was introduced into strains of X . phaseoli and X . campestris pv . malvacearum (neither pathogenic to citrus), the transconjugants remained nonpathogenic to citrus and elicited a hypersensitive response (HR) on their respective hosts, bean and cotton . In X . c . pv . malvacearum, pthA conferred cultivar-specific avirulence . Structurally, pthA is highly similar to avrBs3 and avrBsP from X . c . pv . vesicatoria and to avrB4, avrb6, avrb7, avrBIn, avrB101, and avrB102 from X . c . pv . malvacearum . Surprisingly, marker-exchanged pthA::Tn5-gusA mutant B21.2 of X . citri specifically lost the ability to induce the nonhost HR on bean, but retained the ability to induce the nonhost HR on cotton . The loss of the ability of B21.2 to elicit an HR on bean was restored by introduction of cloned pthA, indicating that the genetics of the nonhost HR may be the same as that found in homologous interactions involving specific avr genes . In contrast with expectations of homologous HR reactions, however, elimination of pthA function (resulting in loss of HR) did not result in water-soaking or even moderate levels of growth in planta of X . citri on bean; the nonhost HR, therefore, may not be responsible for the "resistance" of bean to X . citri and may not limit the host range of X . citri on bean . The pleiotropic avirulence function of pthA and the heterologous HR of bean to X . citri are both evidently gratuitous. Appl Environ Microbiol, 1992 Apr, 58(4), 1183 - 9 Degradation of hydrogen sulfide by Xanthomonas sp . strain DY44 isolated from peat; Cho KS et al.; Xanthomonas sp . strain DY44, capable of degrading H2S, was isolated from dimethyl disulfide-acclimated peat . This bacterium removed H2S either as a single gas or in the presence of the sulfur-containing compounds methanethiol, dimethyl sulfide, and dimethyl disulfide . The maximum specific H2S removal rate, obtained in the late stationary phase, was 3.92 mmol g of dry cells-1 h-1 (6.7 x 10(-16) mol cell-1 h-1) at pH 7 and 30 degrees C through a batch experiment in a basal mineral medium . Since Xanthomonas sp . strain DY44 exhibited no autotrophic growth with H2S, the H2S removal was judged not to be a consequence of chemolithotrophic activity . By using X-ray photoelectron spectroscopy, the metabolic product of H2S oxidation was determined to be polysulfide, which has properties very similar to those of elemental sulfur . Autoclaved cells (120 degrees C, 20 min) did not show H2S degradation, but cells killed by gamma-irradiation and cell extracts both oxidized H2S, suggesting the existence of a heat-labile intracellular enzymatic system for H2S oxidation . When Xanthomonas sp . strain DY44 was inoculated into fibrous peat, this strain degraded H2S without lag time, suggesting that it will be a good candidate for maintaining high H2S removability in the treatment of exhaust gases. Infect Control Hosp Epidemiol, 1992 Apr, 13(4), 201 - 6 Risk factors for epidemic Xanthomonas maltophilia infection/colonization in intensive care unit patients; Villarino ME et al.; OBJECTIVE: To determine risk factors for and modes of transmission of Xanthomonas maltophilia infection/colonization . DESIGN: Surveillance and cohort study . SETTING: A 470-bed tertiary trauma-referral community hospital . PATIENTS: From January 1, 1988 to March 17, 1989, 106 intensive care unit patients developed X maltophilia infection/colonization . We defined a case as any intensive care unit patient who, from July 15, 1988, through March 17, 1989 (epidemic period), had X maltophilia infection/colonization greater than or equal to 48 hours after intensive care unit admission . We identified 45 case patients and 103 control patients (persons in the shock-trauma intensive care unit for greater than or equal to 72 hours during the epidemic period who had no X maltophilia-positive culture) . RESULTS: Cases were significantly more likely to occur in the shock-trauma intensive care unit than in all other intensive care units combined . Mechanical ventilation, tracheostomy, being transported to the hospital by airplane, and receipt of a higher mean number of antimicrobials were risk factors for X maltophilia infection/colonization . Risk of X maltophilia infection/colonization was significantly greater among cases exposed to a patient with a X maltophilia surgical wound infection than among those without such exposure (relative risk = 1.3, p = .03) . Animate and inanimate cultures revealed X maltophilia contamination of the hospital room of a patient with an X maltophilia surgical wound infection, of respiratory therapy equipment in this patient's room, of respirometers shared between patients, and of shock-trauma intensive care unit personnel's hands . Related environmental and clinical isolates were serotype 10 . CONCLUSIONS: Mechanically ventilated patients receiving antimicrobials in the shock-trauma intensive care unit were at increased risk of X maltophilia infection/colonization . Patients with draining X maltophilia surgical wound infections served as reservoirs for X maltophilia, and contamination of the respirometers and the hands of shock-trauma intensive care unit personnel resulted in patient-to-patient transmission of X maltophilia. Epidemiol Infect, 1992 Apr, 108(2), 337 - 41 Prevalence of serotypes of Xanthomonas maltophilia from world-wide sources; Schable B et al.; Since its development in 1988, a serologic typing scheme for Xanthomonas maltophilia, based on 31 O antigens, has been successfully used to serotype isolates involved in nosocomial outbreaks in the United States . To determine if this serotyping scheme would be useful in typing X . maltophilia isolates from world-wide sources, we obtained additional isolates from 10 countries; of 900 isolates tested, 795 (88.3%) were typable . In order of predominance, the three most common serotypes were 10, 3 and 19 . These three serotypes were most frequently associated with respiratory and blood isolates . This serotyping system is useful as an epidemiologic screening method for universal typing of outbreaks of X . maltophilia infections. Antibiot Khimioter, 1992 Apr, 37(4), 16 - 9 {Relation between the morphogenesis of Xanthomonas rubrilineans and biosynthesis of aminopeptidase in the process of growth and development of its producer}; Uvarov NN et al.; The dynamics of growth and development of Xanthomonas rubrilineans, a culture producing intracellular aminopeptidase, was studied . A difference between the growth rate determined by intensity of the total biomass accumulation and the rate of the culture multiplication was found . The difference was due to the presence of two phases in the culture development during the exponential growth: the phase of increasing the linear sizes of the cells and the phase of the culture intensive multiplication . The most intensive synthesis of aminopeptidase was observed during the phase of increasing the linear sizes of the cells . The dynamics of consumption of the main sources of carbon and nitrogen by the culture was investigated. Antibiot Khimioter, 1992 Apr, 37(4), 14 - 6 {Isolation of protoplasts of Xanthomonas rubrilineans and their use in the study of localization of aminopeptidases}; Telesnina GN et al.; The culture of Xanthomonas rubrilineans was able to synthesize a number of intracellular aminopeptidases . To study localization of the enzymes in the cells, a protoplasting procedure was developed providing the yield of 99.7 per cent . The following subcellular fractions were isolated: periplasmic, cytoplasmic and membranous . It was shown that alanine aminopeptidase was a cytoplasmic enzyme and glutamate peptidase was a membrane-bound enzyme. Farmaco, 1992 Apr, 47(4), 509 - 18 Bioactive polymers . 70 . The kinetics of controlled release of neomycin in an alkaline medium; Dumitriu S et al.; Neomycin is coupled on xanthan--a polysaccharide of microbial biosynthesis produced by Xanthomona campestris--through ionic complexation . The kinetics of neomycin release, in vitro, at pH = 8.2 is studied . A release of neomycin, following a zero order kinetics, is observed, regardless of the eluent flow-rate . The neomycin-xanthan complex, protected by a cellulosic membrane, behaves like a monolithic-type device . Diffusion coefficients--increasing with increasing the eluent flow-rate--are also calculated. J Bacteriol, 1992 Apr, 174(8), 2679 - 87 Cloning and characterization of a gene required for the secretion of extracellular enzymes across the outer membrane by Xanthomonas campestris pv . campestris; Hu NT et al.; Nonpathogenic mutants of Xanthomonas campestris pv . campestris, generated from transposon mutagenesis, accumulated extracellular polygalacturonate lyase, alpha-amylase, and endoglucanase in the periplasm . The transposon Tn5 was introduced by a mobilizable, suicidal plasmid, pSUP2021 or pEYDG1 . Genomic banks of wild-type X . campestris pv . campestris, constructed on the broad-host-range, mobilizable cosmid pLAFR1 or pLAFR3, were conjugated with one of the mutants, designated XC1708 . Recombinant plasmids isolated by their ability to complement XC1708 can be classified into two categories . One, represented by pLASC3, can complement some mutants, whereas the other, represented by a single plasmid, pLAHH2, can complement all of the other mutants . Restriction mapping showed that the two recombinant plasmids shared an EcoRI fragment of 8.9 kb . Results from subcloning, deletion mapping, and mini-Mu insertional mutation of the 8.9-kb EcoRI fragment suggested that a 4.2-kb fragment was sufficient to complement the mutant XC1708 . Sequence analysis of this 4.2-kb fragment revealed three consecutive open reading frames (ORFs), ORF1, ORF2, and ORF3 . Hybridization experiments showed that Tn5 in the genome of XC1708 and other mutants complemented by pLASC3 was located in ORF3, which could code for a protein of 83.5 kDa . A signal peptidase II processing site was identified at the N terminus of the predicted amino acid sequence . Sequence homology of 51% was observed between the amino acid sequences predicted from ORF3 and the pulD gene of Klebsiella species. Rev Argent Microbiol, 1992 Apr-Jun, 24(2), 86 - 90 {Production of xanthan gum in immobilized cultures of Xanthomonas campestris}; Anselmo RJ et al.; The efficiency of xanthan production through surface processes was evaluated . The best porous material was selected first . Thereafter, a comparative study was performed using submerged agitated process vs other without agitation but containing the selected porous material . The culture medium used was white potatoes infusion, buffered with K2HPO4 and supplemented with glucose in diverse concentrations . Besides, to evaluate a different type of surface process, three vegetables were valued: Ipomaea batatus, Solanum tuberosum and Daucus carota, with an without glucose supplement . Larger xanthan production was achieved with immobilization of X . campestris vs the conventional method, when the liquid culture medium was used . The highest yield was obtained when the white potatoes infusion was supplemented with glucose 2.5%, yielding a conversion of this saccharide to xanthan up to 58% . When X . campestris was cultured on fragmented vegetables, the highest xanthan gum yield (5.6g) was obtained with Solanum tuberosum supplemented with glucose . This yield indicators that X . campestris used the glucose added as well as the constitutive polysaccharide of this vegetable. Antimicrob Agents Chemother, 1992 Mar, 36(3), 669 - 71 Susceptibility of Xanthomonas maltophilia to six quinolones and study of outer membrane proteins in resistant mutants selected in vitro; Lecso-Bornet M et al.; The in vitro susceptibilities of 75 clinical isolates of Xanthomonas maltophilia to nalidixic acid, five fluoroquinolones, latamoxef, and doxycycline were determined . Spontaneous mutants were selected, at a frequency of about 10(-5) to 10(-7) from four strains by culturing the strains in the presence of each quinolone . Selection in the presence of nalidixic acid provided mutants that were either resistant only to that compound or that exhibited cross-resistance to all the fluoroquinolones tested . Cross-resistance was always observed for mutants selected on any of the five fluoroquinolones . It was always associated with chloramphenicol resistance and, frequently, with doxycycline resistance . The electrophoretic alterations of the outer membrane proteins of the mutants suggest that different mechanisms may be involved in quinolone resistance in X . maltophilia. Mol Microbiol, 1992 Mar, 6(6), 809 - 16 Rapid generation of directed and unmarked deletions in Xanthomonas; Kamoun S et al.; We have devised a rapid four-step procedure for the generation of directed and unmarked chromosomal deletions in bacteria, based on the use of a novel cloning vector containing the Bacillus subtilis sacB gene that encodes levansucrase and confers sucrose sensitivity, which can be used for counter-selection . Using this technique, we describe the construction of a 6.5 kb directed and unmarked deletion in a phytopathogenicity region of the chromosome in Xanthomonas campestris . This procedure allows rapid and easy transfer of a wide variety of mutant allelic DNA to the bacterial chromosome, and should be adaptable to various bacteria besides Xanthomonas spp. J Bacteriol, 1992 Mar, 174(6), 1923 - 31 Cloning and characterization of pathogenicity genes from Xanthomonas campestris pv . glycines; Hwang I et al.; Nonpathogenic mutants of Xanthomonas campestris pv . glycines 8ra were generated with N-methyl-N-nitro-N'-nitrosoguanidine to identify and characterize pathogenicity genes of the bacterium . A total of 16 nonpathogenic mutants were isolated from 2,000 colonies . One mutant, NP1, was chosen for further study . NP1 did not multiply in soybean cotyledons . A genomic library of strain 8ra was constructed in the cosmid pLAFR3, and the cosmids were tested for complementation in NP1 . One cosmid clone, pIH1, which contained a 31-kb insert, complemented mutant NP1 . A restriction map of pIH1 was constructed, and deletion analyses identified a 10-kb HindIII fragment that restored pathogenicity to NP1 . Southern hybridization analysis indicated that DNA sequences in the 10-kb HindIII fragment are conserved among other X . campestris pathovars tested . Three regions responsible for restoring pathogenicity have been identified by Tn3-HoHo1 mutagenesis . A 2.7-kb ClaI fragment was sequenced, and two possible open reading frames (ORF1 and ORF2) were found . Results indicated that ORF2 but not ORF1 may be expressed in Escherichia coli and in X . campestris pv . glycines . The carboxy terminus of the potential polypeptide encoded by ORF2 has an amino acid sequence similar to that of the gamma subunit of oxaloacetate decarboxylase, which is involved in sodium ion transport in Klebsiella pneumoniae. Anal Biochem, 1992 Feb 1, 200(2), 315 - 20 Use of delta-(alpha-aminoadipoyl) chromogenic amides in screening for aminoadipoyl amidohydrolases; Bouvrette P et al.; The synthesis of delta-(alpha-aminoadipoyl) aromatic amides and their use in screening for enzymes able to cleave delta-(alpha-aminoadipoyl) residues off the synthetic amides and cephalosporin C are described . A number of commercially available proteases and peptidases were not active with delta-(alpha-aminoadipoyl) chromogenic amides . Also, most tested microbial strains known to produce acylases did not hydrolyze these compounds . Only one microbial strain, Xanthomonas maltophila, had an appreciable activity toward the racemic form of chromogenic substrates . Activity measured in crude extracts from Xanthomonas cells indicated that this bacterium produces predominantly L-specific aminoadipoyl amidohydrolase and gamma-glutamyl hydrolase . A low level of cephalosporin C and glutaryl-cephalosporin acylase activities was also found. J Bacteriol, 1992 Feb, 174(3), 815 - 23 Expression of the Xanthomonas campestris pv . vesicatoria hrp gene cluster, which determines pathogenicity and hypersensitivity on pepper and tomato, is plant inducible; Schulte R et al.; The hrp gene cluster from Xanthomonas campestris pv . vesicatoria determines functions necessary not only for pathogenicity on the host plants pepper and tomato but also for the elicitation of the hypersensitive reaction on resistant host and nonhost plants . Transcriptional orientation and expression of the hrp loci were determined with hrp::Tn3-gus fusions . In addition, expression of the hrp loci was studied by RNA hybridization experiments . Expression of the hrp genes was not detectable after growth of the bacteria in complex medium or in minimal medium . However, high levels of induction of hrp gene expression were measured during growth of the bacteria in the plant . To search for a plant molecule responsible for this induction, we examined a variety of materials of plant origin for their ability to induce hrp gene expression . Filtrates from plant suspension cultures induced hrp genes to levels comparable to those induced in the plant . The inducing molecule(s) was found to be heat stable and hydrophilic and to have a molecular mass of less than 1,000 daltons. Lett Appl Microbiol, 1992 Feb, 14(2), 65 - 8 Electrotransformation of Xanthomonas campestris by RF DNA of filamentous phage phi Lf; Wang TW et al.; Conditions were optimized for electrotransformation of Xanthomonas campestris pv . campestris by the replicative form (RF) DNA of filamentous phase phi Lf . Early logarithmic cells were washed exhaustively with deionized water and subjected to a pulse at a field strength of 12.5 kV/cm with a 25 microF capacitor and a 400 omega resistor . An efficiency of 5.1 x 10(7) pfu per microgram RF DNA was obtained . Under the same conditions, the broad host range plasmid pLAFR1 (21.6 kb) transformed X . campestris strains at efficiencies around 10(5) pfu per microgram DNA prepared from XcP20H . The advantages of the protocol used in the present study are that the cells can be washed with water instead of complex buffer, and the DNA used can be prepared by the alkaline method of Birnboim & Doly without purification by ultracentrifugation. Lett Appl Microbiol, 1992 Feb, 14(2), 43 - 6 Increase of xanthan production by cloning xps genes into wild-type Xanthomonas campestris; Tseng YH et al.; Previously, genomic banks of Xanthomonas campestris were constructed in Escherichia coli, using mobilizable broad-host-range cosmids as the vectors . Following conjugal transfer, genes involved in the biosynthesis of xanthan polysaccharide (XPS) were cloned by the ability to restore the mucoid phenotype to the non-mucoid mutants . In this study, all clones were transferred into the wild-type strain Xc17 to evaluate the effects of the cloned genes on XPS production . Most clones showed no significant effect; however, two plasmids, pP2401 and pP2201, caused 10 and 15% yield increases, respectively, compared with that of controls . While it was not clear how pP2201 caused the yield increase, the effect of pP2401 seemed to result from elevated phosphomannose isomerase activity . Since XPS synthesis in X . campestris is a very efficient process, only relatively small increases are to be expected; an enhancement of productivity by 10-15% is important to the commercial production of xanthan. J Biomater Appl, 1992 Jan, 6(3), 251 - 60 Bioactive polymers: in vitro and in vivo study of controlled release neomycin; Dumitriu S et al.; Neomycin is coupled on xanthan-a polysaccharide of microbial biosynthesis produced by Xanthomonas campestris-through ionic complexation . The kinetics of neomycin release, in vitro, at pH = 8.2 is studied . A controlled release of neomycin, following a zero order kinetics is observed, regardless of the eluent flow . Neomycin complexed on xanthan, administered in a unique daily dose to patients suffering from dysentery in the 100 cases taken in study, has shown a high clinical efficiency as compared with the treatments with ampicillin or furazolidone, administered for 5-10 days or longer. Int J Artif Organs, 1992 Jan, 15(1), 19 - 24 Pseudomonas septicemia due to deficient disinfectant mixing during reuse; Vanholder R et al.; We describe a cluster of four septicemias with pseudomonas, that occurred in a unit performing formaldehyde reuse of capillary dialyzers . Samples of blood, heparin solutions, dialysate and effluent of reused dialyzers, were evaluated bacteriologically and upon the adequacy of the reuse procedure . Pseudomonas aeruginosa, vesicularis and/or xanthomonas maltophilia were found on the blood cultures obtained during the septicemic reactions, and in the effluent of two reprocessed dialyzers not yet used (greater than 10(4) CFU/ml) . These two dialyzers had also extremely low formaldehyde concentrations (0.0014 and 0.005% versus the expected 4%) . Membrane and antibiogram characteristics of a Pseudomonas aeruginosa strain, recovered from the blood cultures in one patient, and of a strain found in the effluent of one of the two contaminated reprocessed dialyzers, were the same . The problem was attributed to the inadequate mixing of the disinfectant with the tap water used in the automated reprocessing device, in the absence of an alarm disclosing this failure. Endocr Res, 1992, 18(2), 133 - 43 Stimulation of Candida albicans transition by human chorionic gonadotrophin and a bacterial protein; Caticha O et al.; Candida albicans, a dimorphic fungus, is involved commonly in human infections with the mycelium form more associated with pathogenicity . The influence of various hormones and a bacterial protein on the transition from blastospore to mycelium was assessed . Human luteinizing hormone (hLH), chorionic gonadotrophin (hCG), and an hCG-like material purified from a bacteria, Xanthomonas maltophilia (PCG), were able to increase the rate of transition when compared with the controls . The effect of the two hormones and the bacterial peptide were specific, as human follicle stimulating hormone (hFSH), thyroid stimulating hormone (hTSH), growth hormone (hGH), prolactin (hPrl) and rat and bovine LH (rLH, bLH), and bovine albumin and gamma globulin did not affect the transition . The binding of 125I-hCG or 125I-LH to spheroplasts of Candida albicans were competitively displaced by hCG, hLH, and PCG . Scatchard analysis of binding of all three ligands revealed two binding sites with a high-affinity nM Kd . Thus, hCG, hLH, and PCG induce transition of Candida albicans from a blastospore state to a mycelium form, suggesting that these hormones may modify the pathogenicity of Candida albicans. Folia Microbiol (Praha), 1992, 37(2), 102 - 4 Use of whey for production of exocellular polysaccharide by a mutant strain of Xanthomonas campestris; Konicek J et al.; Growth and kinetics of the production of exocellular polysaccharide was studied in a mutant strain of Xanthomonas campestris lac+ during cultivation in a submerged culture in a medium containing whey . The maximum production of the polymer was observed at the initial stage of the stationary growth phase of the culture . The mean production yield was about 1.4% . The results were comparable with those obtained during cultivation on a lactose medium. Int J Syst Bacteriol, 1992 Jan, 42(1), 193 - 8 Reinterpretation of the taxonomic position of Xanthomonas maltophilia and taxonomic criteria in this genus . Request for an opinion; van Zyl E et al.; The inclusion of "Pseudomonas maltophilia" Hugh 1981 in the genus Xanthomonas as Xanthomonas maltophilia (Hugh 1981) Swings et al . 1983 is questioned in view of the significant differences between these two taxa . This reclassification is not acceptable if practical means of differentiation in this genus are considered . The proposed alteration of the description of the genus Xanthomonas is also questionable because of the implications for everyday phytobacteriology . In view of the natural similarities, as well as the profound differences, between X . maltophilia and the genus Xanthomonas, we propose that a new genus should be created for X . maltophilia, which could be placed together with the genus Xanthomonas in a separate natural group. J Bacteriol, 1992 Jan, 174(1), 191 - 9 Genetics of xanthan production in Xanthomonas campestris: the xanA and xanB genes are involved in UDP-glucose and GDP-mannose biosynthesis; Koplin R et al.; The nucleotide sequence of a 3.4-kb EcoRI-PstI DNA fragment of Xanthomonas campestris pv . campestris revealed two open reading frames, which were designated xanA and xanB . The genes xanA and xanB encode proteins of 448 amino acids (molecular weight of 48,919) and 466 amino acids (molecular weight of 50,873), respectively . These genes were identified by analyzing insertion mutants which were known to be involved in xanthan production . Specific tests for the activities of enzymes involved in the biosynthesis of UDP-glucose and GDP-mannose indicated that the xanA gene product was involved in the biosynthesis of both glucose 1-phosphate and mannose 1-phosphate . The deduced amino acid sequence of xanB showed a significant degree of homology (59%) to the phosphomannose isomerase of Pseudomonas aeruginosa, a key enzyme in the biosynthesis of alginate . Moreover, biochemical analysis and complementation experiments with the Escherichia coli manA fragment revealed that xanB encoded a bifunctional enzyme, phosphomannose isomerase-GDP-mannose pyrophosphorylase. Chin J Biotechnol, 1992, 8(3), 187 - 93 Purification and partial characterization of an antibacterial protein LCIII; Liu J et al.; Total proteins were precipitated by (NH4)2SO4 from the overnight culture supernatant of antagonistic bacterium Bacillus subtilis A014, applied to CM52 column and separated into three main peaks . The preparation of peak III showed to inhibit specifically the growth of rice bacterial blight pathogen Xanthomonas compestris pv . oryzea was further purified with Mono S column on FPLC and named antibacterial protein LCIII . The molecular weight of this protein is 26915Da, pI = 9.12 . Analysis of amino acid composition was revealed to be rich in glycine, threonine and serine, and devoid of proline . Twenty-eight amino acids of N-terminal were sequenced by the Edman degradation and computer analysis of this partial sequence showed that antibacterial protein LCIII is a novel one. Chin J Biotechnol, 1992, 8(2), 139 - 44 The production of hybridoma cell line secreting monoclonal antibodies against Xanthomonas campestris pv . oryzae and its application in the classification of strains; Huang B et al.; By the fusion of mouse myeloma cells (SP2/0-Ag14) and spleen cells derived from BALB/c mice immunized with the preparation of Xanthomonas campestris pv . oryzae Ks-6-6, Os-213, Yz-32 and Yz-24, we obtained 12 hybridoma cell lines secreting monoclonal antibodies . None of the McAbs cross-reacted with the other varieties of plant pathogenetic and non-pathogenetic bacteria . The McAbs could distinguish three variant serotypes of strains . Antibody titers of ascites were about 1:10(3)-1:10(6) when measured by ELISA method . The McAbs could differentiate 6 epitopes . Based on the epitopes, the 63 strains of X . campestris pv . oryzae we collected were grouped into nine groups. Ann Intern Med, 1991 Dec 1, 115(11), 849 - 59 Beta-lactam antibiotic therapy in febrile granulocytopenic patients . A randomized trial comparing cefoperazone plus piperacillin, ceftazidime plus piperacillin, and imipenem alone; Winston DJ et al.; OBJECTIVE: To compare the efficacy, toxicity, and cost-effectiveness of double beta-lactam therapy with monotherapy . DESIGN: A randomized, controlled trial . PATIENTS: Febrile, granulocytopenic patients (429) . INTERVENTIONS: Patients were randomly assigned to receive iv cefoperazone (3 g every 12 hours) plus piperacillin (75 mg/kg body weight every 6 hours), ceftazidime (2 g every 8 hours) plus piperacillin (75 mg/kg every 6 hours), or imipenem alone (1.0 g or 0.5 g every 6 hours) . Patients also received prophylactic vitamin K . MEASUREMENTS: Clinical improvement, eradication of the infecting organism, and toxicity in 403 evaluable patients with one or more infections . MAIN RESULTS: Cefoperazone and ceftazidime, when given in combination with piperacillin, were equally effective (response rates of 75% (104 of 138 patients) and 74% (101 of 137 patients), respectively) . Monotherapy with imipenem had a response rate of 82% (111 of 136 patients) and was as effective as double beta-lactam therapy . Overall antibiotic-related toxicity was minimal, although seizures were associated with high doses of imipenem . Seizures occurred in 3 of 29 patients (10.3%) who were receiving 4 g/d of imipenem, in 3 of 136 patients (2.2%) who were receiving cefoperazone plus piperacillin, in 0 of the 132 patients who were receiving ceftazidime plus piperacillin, and in 1 of 106 patients (0.9%) who were receiving 2 g/d of imipenem (P less than 0.005) . The 2-g daily dose of imipenem was as effective as the 4-g daily dose . Diarrhea was more frequent in patients receiving cefoperazone, whereas nausea occurred more often with imipenem . No antibiotic-related hemorrhage or nephrotoxicity was observed . Superinfections caused by beta-lactam-resistant, gram-negative bacilli were uncommon but occurred more frequently with double beta-lactam therapy than with imipenem monotherapy (11 of 268 patients compared with 1 of 135 patients; P = 0.06) . Xanthomonas maltophilia superinfections occurred only in patients receiving imipenem (3 of 135 patients compared with 0 of 268 patients; P = 0.03) . Imipenem monotherapy was the least expensive therapy . CONCLUSIONS: Cefoperazone and ceftazidime were equally effective when used in combination antibiotic therapy with piperacillin . Twice-daily cefoperazone is less expensive than ceftazidime given three times daily . Monotherapy with imipenem, at a daily dose of 2 g, is as efficacious as double beta-lactam therapy and costs less than combination therapy. J Antimicrob Chemother, 1991 Dec, 28(6), 837 - 42 Effect of media composition on the susceptibility of Xanthomonas maltophilia to beta-lactam antibiotics; Bonfiglio G et al.; The susceptibility of Xanthomonas maltophilia strains to beta-lactams was shown to depend on the concentrations at which individual media were prepared . MIC and disc susceptibility tests were performed on solidified Mueller-Hinton and Iso-Sensitest media prepared at 0.1, 0.3, 1, and 3 x the concentrations recommended by the manufacturers . Nine of ten X . maltophilia strains tested showed increasing sensitivity to meropenem, cefotaxime, cefoperazone, piperacillin and latamoxef as the nutrient concentrations of the two media were increased . The opposite pattern was found with one strain (NCTC 10257) on Mueller-Hinton agar . This strain behaved inconsistently on Iso-Sensitest agar . Previous studies have shown that medium-dependent susceptibility in X . maltophilia is not related to beta-lactamase expression . The present study demonstrated that 22 and 25 kDa outer membrane proteins were induced on media with higher nutrient concentrations . The possible relationship of these proteins to sensitivity is considered. J Bacteriol, 1991 Dec, 173(23), 7519 - 24 Location and cloning of the ketal pyruvate transferase gene of Xanthomonas campestris; Marzocca MP et al.; Genes required for xanthan polysaccharide synthesis (xps) are clustered in a DNA region of 13.5 kb in the chromosome of Xanthomonas campestris . Plasmid pCHC3 containing a 12.4-kb insert of xps genes has been suggested to include a gene involved in the pyruvylation of xanthan gum (N.E . Harding, J.M . Cleary, D.K . Cabanas, I . G . Rosen, and K . S . Kang, J . Bacteriol . 169:2854-2861, 1987) . An essential step toward understanding the biosynthesis of xanthan gum and to enable genetic manipulation of xanthan structure is the determination of the biochemical function encoded by the xps genes . On the basis of biochemical characterization of an X . campestris mutant which produces pyruvate-free xanthan gum, complementation studies, and heterologous expression, we have identified the gene coding for the ketal pyruvate transferase (kpt) enzyme . This gene was located on a 1.4-kb BamHI fragment of pCHC3 and cloned in the broad-host-range cloning vector pRK404 . An X . campestris kpt mutant was constructed by mini-Mu(Tetr) mutagenesis of the cloned gene and then by recombination of the mutation into the chromosome of the wild-type strain. J Bacteriol, 1991 Nov, 173(22), 7142 - 50 Expression of the avirulence gene avrBs3 from Xanthomonas campestris pv . vesicatoria is not under the control of hrp genes and is independent of plant factors; Knoop V et al.; The avirulence gene avrBs3 from Xanthomonas campestris pv . vesicatoria pepper race 1 is responsible for the induction of a race-specific hypersensitive reaction in resistant pepper cultivars . A DNA region of 3.7 kb, containing several open reading frames and an internal repetitive region, was shown previously to be necessary for avirulence activity (U . Bonas, R . E . Stall, and B . Staskawicz, Mol . Gen . Genet . 218:127-136, 1989) . The promoter of avrBs3 was identified by using gene fusions to beta-glucuronidase . Also, we mapped the transcription start site and showed that the avrBs3 gene is expressed constitutively in cells grown in minimal or complex medium and in planta . Polyclonal antibodies raised against a fusion protein produced in Escherichia coli allowed the identification of a 122-kDa protein in X . campestris pv . vesicatoria cells expressing the avrBs3 gene . The antibody is specific for AvrBs3 in X . campestris pv . vesicatoria cells but also recognizes homologous proteins in other pathovars of X . campestris . We found that AvrBs3 is localized intracellularly in X . campestris pv . vesicatoria and is mainly in the soluble fraction . The effect of mutations in the hrp gene cluster on the function of AvrBs3 was examined . Expression of AvrBs3 in X . campestris pv . vesicatoria grown in minimal or complex medium is independent of the hrp gene cluster that determines pathogenicity and hypersensitivity to X . campestris pv . vesicatoria . In the plant, however, the hrp genes are required for elicitation of a race-specific resistance response. Mol Plant Microbe Interact, 1991 Nov-Dec, 4(6), 628 - 32 A gene from Xanthomonas campestris pv . vesicatoria that determines avirulence in tomato is related to avrBs3; Canteros B et al.; Strains of Xanthomonas campestris pv . vesicatoria that were avirulent in tomato leaves but virulent in pepper leaves were identified . A cloned gene, avrBsP, from one of the strains, Xv 87-7, converted a virulent strain in tomato to avirulent in tomato . A 1.7-kb subclone containing the avirulence gene cross-hybridized with the avirulence gene, which determines race 1 within the pepper group of strains (avrBs3) . However, the two avirulence genes differ in their biological activity . The base sequences of the two avirulence genes were almost identical through the 1.7-kb segment of avrBsP, with significant differences only in some bases in the repeat region. Mol Plant Microbe Interact, 1991 Nov-Dec, 4(6), 593 - 601 Xanthomonas campestris contains a cluster of hrp genes related to the larger hrp cluster of Pseudomonas solanacearum; Arlat M et al.; All Xanthomonas campestris pathovars tested contain DNA which hybridizes to the large hrp gene cluster of Pseudomonas solanacearum (C.A . Boucher, F . Van Gijsegem, P.A . Barberis, M . Arlat, and C . Zischek, J . Bacteriol . 169:5626-5632, 1987) . Clones carrying these sequences were isolated from genomic libraries of X . campestris pvs . campestris and vitians . Mutagenesis of the corresponding genomic regions of both pathovars gave strains defective in both pathogenicity and hypersensitive response induction . X . c . pv . campestris contained a hrp gene cluster covering about 25 kb, which was homologous and colinear over a continuous 19-kb DNA region with the P . solanacearum hrp cluster . Cross-complementation showed that X . c . pv . vitians and X . c . pv . campestris hrp sequences are functionally interchangeable, but the source of the hrp genes did not determine the compatibility-incompatibility of the host-pathogen interaction . One X . c . pv . campestris Hrp- mutant was "complemented" by specific subclones of the P . solanacearum hrp cluster, suggesting the existence of some functional homology between the clusters of the two species . Expression of hrp genes (studied by lacZ fusions) was repressed in rich medium, and in minimal medium the level of expression depended on the carbon source supplied to the cells . Transcription of hrp genes was not regulated by genes that control the synthesis of extracellular enzymes, which are required for pathogenicity . In addition X . campestris Hrp- mutants produced wild-type levels of these extracellular enzyme activities . These results suggest the existence of two independent sets of pathogenicity genes that are regulated differently. J Med Microbiol, 1991 Oct, 35(4), 208 - 13 Susceptibility to beta-lactam antibiotics of mutant strains of Xanthomonas maltophilia with high- and low-level constitutive expression of L1 and L2 beta-lactamases; Akova M et al.; Xanthomonas maltophilia produces two inducible beta-lactamases, L1 and L2, and resists the antimicrobial activity of beta-lactam antibiotics, including carbapenems . L1 is a zinc-metaloenzyme with carbapenemase activity; L2 is an unusual cephalosporinase . Mutant strains with high- and low-level constitutive expression of these enzymes were derived from three reference strains of X . maltophilia . With a single exception, the mutant strains had altered expression of both enzymes, indicating that these beta-lactamases share regulatory components . The exception was a mutant strain that had low-level constitutive (basal) expression of L1 enzyme but remained inducible for L2 . A parent strain with low-level beta-lactamase inducibility was more susceptible to penicillins, cephalosporins and carbapenems than were those in which higher levels of enzyme activity were inducible . Mutations that caused high-level constitutive beta-lactamase expression increased resistance to penicillins and newer cephalosporins . beta-Lactamase basal mutant strains, including the one that remained inducible for L2 enzyme, were more susceptible than inducible strains to these drugs . Organisms with inducible or high-level constitutive beta-lactamase expression were equally resistant to meropenem and imipenem but basal mutant strains, including the one that remained inducible for L2 enzyme, were more susceptible to meropenem than imipenem . Minimal inhibitory concentrations of meropenem, penicillins and cephalosporins, but not imipenem, were greater on Mueller Hinton agar than on IsoSensitest or Diagnostic Sensitivity Test agars . This behaviour was independent of beta-lactamase inducibility, and may reflect permeability differences between cells grown on different media. Mol Gen Genet, 1991 Oct, 229(2), 278 - 84 Conservation of xcp genes, involved in the two-step protein secretion process, in different Pseudomonas species and other gram-negative bacteria; de Groot A et al.; The two-step protein secretion pathway in Pseudomonas aeruginosa is dependent on the xcp genes . We investigated whether a similar secretion mechanism is present in non-pathogenic Pseudomonas spp . and in other gram-negative bacteria . The plant growth stimulating Pseudomonas strains P . putida WCS358, P . fluorescens WCS374 and Pseudomonas B10 appeared to secrete proteins into the extracellular medium . Southern hybridization experiments showed the presence of xcp genes in these strains and also in other gram-negative bacteria, including Xanthomonas campestris . Complementation experiments showed that the xcp gene cluster of P . aeruginosa restored protein secretion in an X . campestris secretion mutant . The secretion gene cluster of X . campestris however, restored secretion capacity in P . aeruginosa mutants only to a low degree . Two heterologous proteins were not secreted by P . fluorescens and P . aeruginosa . The results suggest the presence of a similar two-step protein secretion mechanism in different gram-negative bacteria, which however, is not always functional for heterologous proteins. Mol Microbiol, 1991 Oct, 5(10), 2503 - 9 Environmentally regulated algD promoter is responsive to the cAMP receptor protein in Escherichia coli; DeVault JD et al.; The environmentally activated algD promoter of Pseudomonas aeruginosa has been shown to be influenced by DNA supercoiling . It is believed that protein-induced bending or looping is required for this activation . We studied the role of Escherichia coli cAMP-CRP on algD promoter activation in E . coli and show that a functional CRP is required for this activation . We also demonstrate that the algD promoter is sensitive to glucose repression both in E . coli and P . aeruginosa . Deletion of a putative consensus CRP binding sequence upstream of the algD promoter renders the promoter non-responsive to glucose repression . The involvement of cAMP-CRP complex in the activation of the algD promoter in E . coli has been demonstrated directly through binding of a 255 base pair DNA fragment containing the putative consensus CRP binding sequence . Other fragments, upstream or downstream but without any consensus CRP binding sequence, did not show any binding with CRP . A CRP-like analogue, similar to that in Xanthomonas campestris, but capable of activating genes without forming a complex with cAMP, is believed to allow glucose repression in P . aeruginosa. J Bacteriol, 1991 Oct, 173(20), 6421 - 7 Use of cloned DNA methylase genes to increase the frequency of transfer of foreign genes into Xanthomonas campestris pv . malvacearum; De Feyter R et al.; In vitro-packaged cosmid libraries of DNA from the bacterium Xanthomonas campestris pv . malvacearum were restricted 200- to 1,000-fold when introduced into Mcr+ strains of Escherichia coli compared with restriction in the Mcr- strain HB101 . Restriction was predominantly associated with the mcrBC+ gene in E . coli . A plasmid (pUFR052) encoding the XmaI and XmaIII DNA methylases was isolated from an X . campestris pv . malvacearum library by a screening procedure utilizing Mcr+ and Mcr- E . coli strains . Transfer of plasmids from E . coli strains to X . campestris pv . malvacearum by conjugation was enhanced by up to five orders of magnitude when the donor cells contained pUFR052 as well as the plasmid to be transferred . Subcloning of pUFR052 revealed that at least two regions of the plasmid were required for full modification activity . Use of such modifier plasmids is a simple, novel method that may allow the efficient introduction of genes into any organism in which restriction systems provide a potent barrier to such gene transfer. J Biol Chem, 1991 Sep 25, 266(27), 18154 - 61 Fructose catabolism in Xanthomonas campestris pv . campestris . Sequence of the PTS operon, characterization of the fructose-specific enzymes; de Crecy-Lagard V et al.; In Xanthomonas campestris pv . campestris, fructose is transported and phosphorylated into fructose 1-phosphate through a phosphoenolpyruvate-dependent phosphotransferase system . The nucleotide sequence of the fruA gene encoding the phosphotransferase system permease specific of fructose (EIIFru) was determined . The fructose 1-phosphate produced by the phosphotransferase system is phosphorylated into fructose 1,6-bisphosphate by a 1-phosphofructokinase . This enzyme was characterized and the corresponding gene (fruK) was sequenced . Sequence comparisons revealed that FruK is a member of a new family of ATP-binding proteins composed of sugar (or sugar-phosphate) kinases . In phosphotransferase system-deficient strains, fructose can still be transported by an unidentified permease . The intracellular fructose is then phosphorylated by a multimeric fructokinase of 135 kDa specific for fructose and inhibited by fructose, fructose 1,6-bisphosphate, and mannose . Several other enzymes of fructose metabolism were assayed and a potential pathway for fructose catabolism is presented. Diagn Microbiol Infect Dis, 1991 Sep-Oct, 14(5), 447 - 50 In vitro susceptibility of 33 clinical case isolates of Xanthomonas maltophilia . Inconsistent correlation of agar dilution and of disk diffusion test results; Hohl P et al.; Xanthomonas maltophilia is an emerging nosocomial pathogen, possibly selected by a changing antimicrobial usage and patient population . In the present study, we tested the susceptibility of 33 recent clinical case isolates to 12 commonly employed antimicrobials . Trimethoprim-sulfamethoxazole (1:19 ratio) and doxycycline were uniformly the most active agents; ciprofloxacin and fleroxacin were slightly less active and, along with tetracycline and ceftazidime, more variable in their potency . Interestingly, the disk diffusion method routinely overstated the activity of ciprofloxacin (12% very major errors, 58% minor errors) . The present in vitro data and the hitherto accumulated clinical experience suggest that in the absence of unequivocal clinical efficacy of ciprofloxacin against this increasingly recognized nosocomial pathogen, the decision to use ciprofloxacin or any other fluoroquinolone against these pathogens should rely preferentially on the dilution susceptibility test method results . In contrast, the present study confirms the excellent predictive value of trimethoprim-sulfamethoxazole, tetracycline, and fleroxacin disks as well as the higher (9% minor errors) inhibitory activity of these drugs . Hence, pending the elaboration of clinical efficacy data of alternative antimicrobial agents against X . maltophilia infections, trimethoprim-sulfamethoxazole remains a sound therapeutic choice. New Biol, 1991 Aug, 3(8), 780 - 8 Site-specific recombination promoted by a short DNA segment of plasmid R1 and by a homologous segment in the terminus region of the Escherichia coli chromosome; Clerget M; A short DNA segment located in the kanamycin resistance region of plasmid R1 promotes site-specific recombination and plasmid maintenance . This segment has been reduced to 100 bp and subsequently to 44 bp without losing these properties . It can recombine with a similar segment located in the terminus region of the Escherichia coli chromosome . It is proposed that this recombination is responsible for the plasmid maintenance properties of the R1 segment . The chromosomal site has been isolated; it also shows site-specific recombination activity . Sequence homologies were also found with a phage site-specific integration locus in the chromosome of Xanthomonas campestris and with the plasmid ColE1 site-specific recombination locus . The recombinase required in all these systems is probably XerC, an E . coli enzyme acting on the cer site of plasmid ColE1 for the conversion of plasmid dimers to monomers . It is postulated that site-specific recombination in the terminus region of the chromosome intervenes in the partitioning of the two daughter chromosomes. Appl Environ Microbiol, 1991 Aug, 57(8), 2435 - 9 DNA probes for detection of copper resistance genes in Xanthomonas campestris pv . vesicatoria; Garde S et al.; The copper resistance (Cur) genes encoded on pXV10A, a 190-kb plasmid in Xanthomonas campestris pv . vesicatoria XV10, were isolated on a 44-kb cosmid clone designated pCuR1 . Tn5 mutagenesis of pCuR1 indicated that a 4.0-kb region was required for copper resistance . Three restriction fragments located within the 4.0-kb region demonstrated high specificity for the Cur genes present in X . campestris pv . vesicatoria and will be useful in monitoring the presence of these genes in the environment. J Clin Microbiol, 1991 Jul, 29(7), 1348 - 50 DNA restriction fragment length polymorphism differentiates crossed from independent infections in nosocomial Xanthomonas maltophilia bacteremia; Bingen EH et al.; Restriction fragment length polymorphisms of total DNA and rDNA were used to study the relationship between 11 isolates of Xanthomonas maltophilia, obtained from seven patients with nosocomial bacteremia in four distinct wards of a single hospital, and the type strain of the species, ATCC 13637 . Our results indicated that there were episodes of cross-infection among the patients of two wards, but there were also independent infectious episodes in the two other wards. Mol Gen Genet, 1991 Jul, 227(3), 465 - 72 Identification of two fructose transport and phosphorylation pathways in Xanthomonas campestris pv . campestris; de Crecy-Lagard V et al.; Fructose was shown to be phosphorylated by a specific phosphoenolpyruvate-dependent phosphotransferase system (PTS) in Xanthomonas campestris pv . campestris . Transposon mutagenesis of X . campestris was performed and two mutants affected in growth on fructose were isolated . Both mutants were deficient in PTS activity . Comparison of the rate of uptake and phosphorylation of fructose in the wild-type and in the mutant strains revealed the presence of a second fructose permeation and phosphorylation pathway in this bacterium: an unidentified permease coupled to an ATP-dependent fructokinase . One of the two mutants was also deficient in fructokinase activity . Chromosomal DNA fragments containing the regions flanking the transposon insertion site were cloned from both mutant strains . Their physical study revealed that the insertion sites were separated by 1.4 kb, allowing the reconstruction of a wild-type DNA fragment which complemented one of the two mutants . The region flanking the transposon insertion site was sequenced in one of the mutants, showing that the transposon had interrupted the gene encoding the fructose EII . The mutant strains also failed to utilize mannose, sucrose and mannitol, suggesting the existence of a branch point between the metabolism of fructose and of these latter carbohydrates. J Chemother, 1991 Jun, 3(3), 143 - 6 In-vitro activity of meropenem, a new carbapenem, against imipenem-resistant Pseudomonas aeruginosa and Xanthomonas maltophilia; Garcia-Rodriguez JA et al.; The activity of meropenem, a new carbapenem, as well as imipenem, ceftazidime, aztreonam, tobramycin, amikacin and ciprofloxacin against 18 strains of Xanthomonas maltophilia and 23 strains of Pseudomonas aeruginosa resistant to imipenem was tested . All strains of X . maltophilia were resistant to both penems . Ceftazidime, tobramycin and ciprofloxacin were the most active antimicrobial agents against this specie . 17% of imipenem-resistant strains of P . aeruginosa were sensitive to meropenem . Ciprofloxacin, amikacin and aztreonam were the most effective agents against these strains. J Antimicrob Chemother, 1991 Jun, 27(6), 793 - 9 Comparative in-vitro susceptibilities of Pseudomonas aeruginosa, Xanthomonas maltophilia, and Pseudomonas spp . to sparfloxacin (CI-978, AT-4140, PD131501) and reference antimicrobial agents; Louie A et al.; The susceptibility of sparfloxacin, a new broad spectrum fluoroquinolone, was determined for 72 clinical isolates of Pseudomonas aeruginosa, 15 Xanthomonas maltophilia, and 19 Pseudomonas spp . The activity of sparfloxacin was compared with that of ciprofloxacin and other reference antibiotics . Sparfloxacin was the most active antibiotic tested against X . maltophilia (MIC90 1 mg/l) and the most active quinolone against P . cepacia and P . putrifaciens . Ciprofloxacin, however, demonstrated greater activity than sparfloxacin against P . fluorescens and P . stutzeri . P . aeruginosa was most susceptible to ciprofloxacin with an MIC90 of 2 mg/l, compared with an MIC90 of 8 mg/l for sparfloxacin and ofloxacin . Although cross-resistance between quinolones was noted, cross-resistance between antibiotic classes was not seen . Aminoglycoside-resistant and aminoglycoside-susceptible P . aeruginosa strains were equally susceptible to sparfloxacin . Kill curves showed sparfloxacin to be rapidly bactericidal against P . aeruginosa at 1 x MIC . Sparfloxacin demonstrated greater bactericidal activity than ciprofloxacin at 1 x and 2 x their MICs . Unlike ciprofloxacin and gentamicin, sparfloxacin showed sustained bactericidal activity at greater than or equal to 1 MIC for 24 h. Diagn Microbiol Infect Dis, 1991 May-Jun, 14(3), 239 - 43 Antibiotic susceptibility profile of Xanthomonas maltophilia . In vitro activity of beta-lactam/beta-lactamase inhibitor combinations; Garcia-Rodriguez JA et al.; The susceptibility of 42 strains of Xanthomonas (Pseudomonas) maltophilia to 37 antibiotics (mainly beta-lactams, aminoglycosides, and fluorinated quinolones) was tested . Xanthomonas maltophilia was resistant to most beta-lactams, with ceftazidime, moxalactam, and ICI-194008 being the most active ones . Aminoglycosides had a very modest activity, with quinolones showing only moderate activity against this species . Trimethoprim/sufamethoxazole was effective against all strains tested . We also tested the synergy of several beta-lactam/beta-lactamase inhibitors against X . maltophilia . Only aztreonam/clavulanic acid at 3:1, 1:1 and, mainly, 2:1 combinations had synergistic activity, decreasing the rate of resistance from 92.8% for aztreonam alone to 32.4% for aztreonam-clavulanic acid at 1:1 and 0% for aztreonam-clavulanic acid at 2:1. Mol Gen Genet, 1991 May, 226(3), 409 - 17 Genetic and molecular analysis of a cluster of rpf genes involved in positive regulation of synthesis of extracellular enzymes and polysaccharide in Xanthomonas campestris pathovar campestris; Tang JL et al.; The cosmid clone pIJ3020 containing DNA from the plant pathogenic bacterium Xanthomonas campestris pathovar campestris has previously been shown to complement a non-pathogenic mutant defective in synthesis of extracellular enzymes . The DNA cloned in pIJ3020 was analysed by mutagenesis with Tn5 and Tn5lac and by nucleotide sequencing . The results indicate that this region of the genome contains a cluster of genes, mutation in any of which results in failure of the enzymes and extracellular polysaccharide to be synthesized . The designation rpf (regulation of pathogenicity factors) is proposed for these genes . The nucleotide sequence of one gene (rpfC) predicts a protein product with homology to conserved domains of both sensor and regulator proteins of prokaryotic two-component regulatory systems, which are usually involved in regulating gene expression in response to environmental stimuli. J Dermatol, 1991 Apr, 18(4), 225 - 9 Purpura fulminans secondary to Xanthomonas maltophilia sepsis in an adult with aplastic anemia; Kato N et al.; Purpura fulminans is a rare disease characterized by purpura ecchymosis, hypotension, and fever associated with disseminated intravascular coagulation . It often begins as a benign infectious process and subsequently progresses to a severe, catastrophic outcome . It is recognized to originate from congenital or acquired protein C deficiency . We present an unusual case of an adult with Xanthomonas maltophilia sepsis that subsequently developed into purpura fulminans with involvement of the four extremities . We discuss the importance of the protein C system in coagulation homeostasis and its relationship to purpura fulminans. Rev Argent Microbiol, 1991 Apr-Jun, 23(2), 97 - 100 {Production of xanthan gums}; Pares EP et al.; Xanthomonas campestris was investigated in 70 samples of infected plants in the neighbourhood of Lujan, province of Buenos Aires, between February and August, 1990 . The production of xanthan gum was determined from 50 strains of Xanthomonas campestris, as well as the conversion efficiency of substrate concentration into gum and the number of colony forming units (CFU) of Xanthomonas campestris/ml of broth culture . The highest number of strains producing extracellular polysaccharide was obtained from alfalfa . Xanthomonas campestris pv . alfalfa gave elevated cell concentration and conversion efficiency of glucose in xanthan gum. Infect Control Hosp Epidemiol, 1991 Mar, 12(3), 163 - 7 Application of multilocus enzyme electrophoresis to epidemiologic investigations of Xanthomonas maltophilia; Schable B et al.; OBJECTIVE: To test the utility of a newly developed multilocus enzyme electrophoresis typing method for Xanthomonas maltophilia . DESIGN: Isolates were first screened by slide agglutination, which served as the standard to characterize the outbreak strains . All isolates were then subjected to multilocus enzyme electrophoresis and the results analyzed based on epidemiological data . SETTING: This outbreak occurred in a shock-trauma intensive care unit of a large general community hospital . PATIENTS: Patients admitted to the shock-trauma intensive care unit who had X maltophilia isolated from any site greater than or equal to 24 hours after admission met the case definition . Specimens from patients who fit the case definition were characterized, as were specimens from other patients that were used as controls for nonoutbreak isolates . Environmental samples were also evaluated for X maltophilia . RESULTS: Most of the 64 isolates received during this outbreak were serotype 10, and when they were subjected to multilocus enzyme electrophoresis, one electrophoretic type predominated and correlated to most outbreak isolates . Unrelated isolates of serotype 10 from other institutions all exhibited unique electrophoretic types . CONCLUSION: Application of multilocus enzyme electrophoresis to X maltophilia outbreaks is a valuable addition to the characterization of suspected outbreak strains. J Hosp Infect, 1991 Mar, 17(3), 187 - 95 Rapid inter-strain comparison by pyrolysis mass spectrometry in nosocomial infection with Xanthomonas maltophilia; Orr K et al.; Seventeen strains of Xanthomonas maltophilia and one strain of Pseudomonas cepacia were examined by pyrolysis mass spectrometry (PYMS) . The Xanthomonas strains comprised 11 clinical and environmental isolates from a suspected outbreak of colonization and infection on a heart-lung transplant intensive care unit, two strains from patients elsewhere in the same hospital and four strains from a national reference collection . The single isolate of Pseudomonas cepacia was from a sink in the same affected intensive care unit . A series of discriminant analyses performed on the PYMS-derived data showed that, whereas six strains of Xanthomonas from the respiratory tract, blood and ventilatory equipment of one of the affected patients were indistinguishable, all the other isolates were distinct . The results of PYMS rapid inter-strain comparison were in accord with those of an epidemiological investigation which suggested that the episode was due to unauthorized reuse of disposable nebulizers and not to cross-infection between patients . Pyrolysis mass spectrometry with rapid data analysis is a potentially useful technique for the investigation of nosocomial infections due to organisms such as X . maltophilia. Chemotherapy, 1991, 37(4), 246 - 50 Antibiotic susceptibility and outer membrane proteins of clinical Xanthomonas maltophilia isolates; Cullmann W; Twenty clinical Xanthomonas maltophilia isolates were studied for their susceptibility to various antibiotics and for their outer membrane protein profiles and compared to Pseudomonas aeruginosa isolates . Among the antibiotics studied, fleroxacin and ciprofloxacin exhibited the greatest activity (MIC90 4 micrograms/ml) . All the X . maltophilia isolates exhibited similar outer membrane protein profiles with 40, 23 and 21 major proteins, whereas the outer membrane of P . aeruginosa revealed at least 7 major outer membrane proteins, as is known from the literature . Thus, it is assumed that the outer membrane profile of X . maltophilia contributes to the resistance of this nosocomial pathogen to most antibiotics. Rev Argent Microbiol, 1991 Jan-Feb, 23(1), 41 - 7 {Evaluation of culture media for detecting the starch hydrolysis reaction in pathovars of Xanthomonas campestris}; Alippi AM; Sixty strains of different pathovars of Xanthomonas campestris have been tested for the evaluation of various starch agars and compounds of starch degradation on six media: soluble starch, potato insoluble starch, corn insoluble starch, potato amylopectin, corn amylopectin and potato amylose . The purpose of the present investigation was the selection of the most suitable medium for the visualization of the starch hydrolysis test, presenting this reaction as a distinct character between pathovars of the Xanthomonas campestris group . From 60 strains tested, 74% gave positive reactions . Pathovars holcicola, pelargonii, pruni and vitians were negative . Regarding X . campestris pv . vesicatoria cultures, results were variable . Potato and corn insoluble starch agars were the most suitable media for the visualization of the starch hydrolysis reaction and at the same time the most appropriate for direct isolation . Differentiation at species level could be practicable, but within the Xanthomonas campestris group, variation amongst pathovars suggest the unsuitability of the test in spite of the high percentage of positive reactions. Biokhimiia, 1990 Dec, 55(12), 2226 - 38 {Intracellular aminopeptidase from Xanthomonas rubrilineans, hydrolyzing alpha-amino acid esters and cefalexin}; Krest'ianova IN et al.; The aminopeptidase was isolated from cell-free extracts of Xanthomonas rubrilineans by protein precipitation by isopropyl ester with subsequent purification by affinity chromatography on CABS-Sepharose, bacitracin-Sepharose, gel filtration through Sephadex G-200 and ultrafiltration, the total yield being 32% with 2200-fold purification . The enzyme was homogeneous during SDS-PAAG electrophoresis . Apart from the broad spectrum of the peptidase activity, aminopeptidase possesses a hydrolase activity towards beta-lactam antibiotics and an esterase activity towards L- and D-amino acids . Besides, this enzyme catalyzes the acetyl transfer reaction during cephalexin synthesis from the D-phenylglycine ester and 7-aminodesacetoxycephalosporanic acid . The maximal enzyme activity during L-Ala-pNA and cephalexin hydrolysis is manifested at pH 6.5 . The enzyme is stable at pH 4.0-8.0 and is inhibited by o-phenanthroline, p-chloromercuribenzoate, hydrogen acetate and N-bromosuccinimide . The molecular mass of the enzyme is 270-280 kDa . The enzyme is a tetramer; the molecular mass of each of its four subunits is 70 +/- 2 kDa . The isoelectric point for the enzyme is 6.8 . The amino acid composition of the enzyme appears as follows: Asp63, Thr33, Ser32, Glu72, Gly55, 1/2Cys3-4, Val45, Ile24, Leu53, Tyr23, Phe24, Lys23, His16, Arg36, Pro60, Met25, Ala55. Appl Environ Microbiol, 1990 Oct, 56(10), 2994 - 8 Extracellular proteases from Xanthomonas campestris pv . campestris, the black rot pathogen; Dow JM et al.; Two proteases (PRT1 and PRT2) were fractionated from culture supernatants of wild-type Xanthomonas campestris pv . campestris by cation-exchange chromatography on SP-5PW . Inhibitor experiments showed that PRT 1 was a serine protease which required calcium ions for activity or stability or both and that PRT 2 was a zinc-requiring metalloprotease . PRT 1 and PRT 2 showed different patterns of degradation of beta-casein . The two proteases comprised almost all of the extracellular proteolytic activity of the wild type . A protease-deficient mutant which lacked both PRT 1 and PRT 2 showed considerable loss of virulence in pathogenicity tests when bacteria were introduced into mature turnip leaves through cut vein endings . This suggests that PRT 1 and PRT 2 have a role in black rot pathogenesis. Int J Syst Bacteriol, 1990 Oct, 40(4), 348 - 69 Numerical analysis of 295 phenotypic features of 266 Xanthomonas strains and related strains and an improved taxonomy of the genus; Van den Mooter M et al.; An extensive phenotypic description and an improved classification and nomenclature of the genus Xanthomonas are presented . A total of 266 strains obtained from different geographical areas, including representative strains of all species of the genus Xanthomonas and most pathovars of Xanthomonas campestris, as well as strains which might be genetically related to the genus Xanthomonas, were examined for 295 morphological, biochemical, and physiological features . Similarities among the strains were expressed numerically by using the coefficient of Sokal and Michener . Clustering was performed by using the unweighted average pair group method . The conclusions described below were reached . (i) The genus Xanthomonas comprises at least the following eight phena: X . campestris, Xanthomonas albilineans, Xanthomonas axonopodis, Xanthomonas fragariae, Xanthomonas populi, Xanthomonas maltophilia, Xanthomonas oryzae Swings et al . 1990, and X . campestris pv . graminis Egli and Schmidt 1982 {not X . campestris pv . graminis (Egli et al . 1975) ISPP List 1980} . (ii) X . populi (Ride 1958) Ride and Ride 1978 is a separate species . (iii) X . maltophilia Swings et al . 1983 forms a separate species . (iv) X . campestris pv . oryzae ISPP List 1980 can no longer be regarded as pathovar of X . campestris, and its recent reclassification as a new species, X . oryzae (Swings et al., Int . J . Syst . Bacteriol . 40:309-311, 1990), is supported . (v) X . campestris pv . graminis Egli and Schmidt 1982 {not X . campestris pv . graminis (Egli et al . 1975) ISPP List 1980} seems to form a separate complex of highly related pathovars obtained from members of the Poaceae; the taxonomic implications of this are discussed . (vi) Strains of nearly all X . campestris pathovars cluster together in the X . campestris phenon . Within this species we were able to differentiate some entities on phenotypic grounds; these groups sometimes corresponded to named pathovars (e.g., X . campestris pv . manihotis, X . campestris pv . cassavae, X . campestris pv . phlei) . In several other cases, pathovars were found to be heterogeneous . (vii) A number of dubious Pseudomonas species were identified as members of or as being close to Xanthomonas species . Both Pseudomonas betle and Pseudomonas hibiscicola are synonyms of X . maltophilia . We also confirmed that Pseudomonas mangiferaeindicae, Pseudomonas vitiswoodrowii, and Pseudomonas gardneri belong to X . campestris . (viii) Forty phenotypic features allow the differentiation of the eight Xanthomonas phena . (ix) A number of additional features of the genera Xanthomonas and Xylophilus are described. J Bacteriol, 1990 Oct, 172(10), 5877 - 83 A Xanthomonas campestris pv . campestris protein similar to catabolite activation factor is involved in regulation of phytopathogenicity; de Crecy-Lagard V et al.; A DNA fragment from Xanthomonas campestris pv . campestris that partially restored the carbohydrate fermentation pattern of a cya crp Escherichia coli strain was cloned and expressed in E . coli . The nucleotide sequence of this fragment revealed the presence of a 700-base-pair open reading frame that coded for a protein highly similar to the catabolite activation factor (CAP) of E . coli (accordingly named CLP for CAP-like protein) . An X . campestris pv . campestris clp mutant was constructed by reverse genetics . This strain was not affected in the utilization of various carbon sources but had strongly reduced pathogenicity . Production of xanthan gum, pigment, and extracellular enzymes was either increased or decreased, suggesting that CLP plays a role in the regulation of phytopathogenicity. Medicine (Baltimore), 1990 Sep, 69(5), 296 - 306 Septicemia due to Xanthomonas species and non-aeruginosa Pseudomonas species: increasing incidence of catheter-related infections; Elting LS et al.; We reviewed 149 episodes of septicemia caused by X . maltophilia and Pseudomonas spp . occurring over a 15-year period . The incidence of septicemia caused by these organisms increased in recent years and was most frequently associated with central venous catheterization . These infections were occasionally complicated by pneumonia or endocarditis, which was often fatal . Although the survival rate was superior to that seen with septicemia caused by other gram-negative organisms, recurrence of infection was significantly more frequent . Removal of central venous catheters is an essential component of therapy of this infection. J Bacteriol, 1990 Sep, 172(9), 5165 - 72 A plant-inducible gene of Xanthomonas campestris pv . campestris encodes an exocellular component required for growth in the host and hypersensitivity on nonhosts; Kamoun S et al.; Using Tn4431, a transposon that allows transcriptional fusions to a promoterless luciferase (lux) operon, we have isolated a nonpathogenic mutant of Xanthomonas campestris pv . campestris, i.e., JS111, that does not incite any of the black rot symptoms on all tested cruciferous host plants (J . J . Shaw, L . G . Settles, and C . I . Kado, Mol . Plant Microbe Interact . 1:39-45, 1988) . In the study reported here, we determined that in contrast to the wild-type strain, JS111 is unable to induce a hypersensitive necrotic response on nonhost plants such as datura, tomato, and cucumber, suggesting that JS111 is a nonpathogenic, nonhypersensitive Hrp mutant . JS111 displayed culture growth rates, exopolysaccharide production, and protease, pectate lysase, cellulase, amylase, and phosphatase activities comparable to those of the wild-type strain . However, the growth of JS111 in host leaves was markedly attenuated . Coinoculation of JS111 with the wild-type strain in cauliflower or radish leaves rescued the growth deficiency of the mutant to normal levels . The locus mutated in JS111 was cloned and named hrpXc, and transcriptional and genetic complementation analyses of the hrpXc locus were conducted . The regulation of hrpXc expression was also investigated in vitro and in planta, using fusions to a lux or chloramphenicol acetyltransferase reporter gene . The hrpXc gene was found to be strongly induced in radish leaves . This is the first report and analysis of a hrp locus from a Xanthomonas species. Mol Plant Microbe Interact, 1990 Sep-Oct, 3(5), 280 - 5 Identification and DNA sequence of a pathogenicity gene of Xanthomonas campestris pv . campestris; Osbourn AE et al.; A region of Xanthomonas campestris pv . campestris DNA containing at least two pathogenicity genes was identified . Mutants in one gene were clearly reduced in pathogenicity while mutants in the other were only moderately reduced . Both classes of mutants were prototrophic and motile, and had wild-type levels of extracellular enzymes and extracellular polysaccharide . They also grew in vitro and in planta at the same rate as the wild type . Experiments involving one of the clear pathogenicity mutants indicated that the recovery of mutant cells from turnip seedlings 24 hr after inoculation was lower than for the wild type . This may be due to cell death as a result of action by some preformed or induced plant factor . From DNA sequencing an open reading frame was identified that encompassed the site of the mutations giving a clear reduction in pathogenicity . The predicted protein sequence had no homology with other proteins in the computer data base. J Gen Virol, 1990 Aug, 71 ( Pt 8), 1881 - 4 Characterization of filamentous bacteriophage phi Lf from Xanthomonas campestris pv . campestris; Tseng YH et al.; A filamentous phage, phi Lf, which specifically infects Xanthomonas campestris pv . campestris was isolated . The phage particle measured 1,000 (+/- 200) x 8 nm . It formed turbid plaques of about 1 mm in diameter . During multiplication, the progeny virions extruded into the medium without retarding host cell growth . Stocks were stable for 6 months at 4 degrees C and survived treatment at 80 degrees C for 10 min . Treatment with chloroform, ethanol or acetone completely destroyed infectivity; ethyl ether and methanol inactivated 98 to 99% of the phage . SDS-polyacrylamide gel electrophoresis showed a major coat protein band of approximate Mr 4000 whereas an immunoprecipitation test detected the existence of two coat protein species . The phage genome was shown to be a single-stranded DNA molecule . A physical map was constructed and the DNA size was calculated to be 5.9 kb . Cells treated with Tris-HCl containing CaCl2 and polyethylene glycol 6000 were transfected by replicative form DNA at a frequency of 3.4 x 10(3) p.f.u./micrograms. Antimicrob Agents Chemother, 1990 Aug, 34(8), 1609 - 10 In vitro susceptibility of Xanthomonas (Pseudomonas) maltophilia to newer antimicrobial agents; Khardori N et al.; The susceptibilities of 45 clinical and 3 environmental isolates of Xanthomonas maltophilia to 14 antimicrobial agents was determined by broth microdilution . The newer quinolones PD117596, PD117558, PD127391, A-56620, amifloxacin, and fleroxacin were the most active agents tested, with 70 to 99% of isolates being susceptible to these agents . All isolates were resistant to trospectomycin . The new aminoglycosides SCH24120 and SCH22591 were active against 12 and 1% of isolates, respectively. Nature, 1990 Jul 26, 346(6282), 385 - 6 Widespread distribution and fitness contribution of Xanthomonas campestris avirulence gene avrBs2; Kearney B et al.; Disease-resistance genes introduced into cultivated plants are often rendered ineffective by the ability of pathogen populations to overcome host resistance . The bacterial pathogen Xanthomonas campestris pathovar vesicatoria causes bacterial spot disease of tomato and pepper, and this pathogen has been shown to overcome disease resistance in pepper (Capsicum annuum) by evading the recognition and defence response of the host plant . Numerous resistance genes to bacterial spot have been identified in pepper and its wild relatives, each providing resistance to specific races of X.c . vesicatoria . The resistance gene Bs1, for example, provides resistance to X.c . vesicatoria strains expressing the avirulence gene avrBs1; Bs2 provides resistance to stains expressing avrBs2 and so on . We now report that avr Bs2 is highly conserved among strains of X.c . vesicatoria, and among many other pathovars of X . campestris . Furthermore, we find that avrBs2 is in fact needed for full virulence of the pathogen on susceptible hosts . This implies that plants carrying Bs2 can recognize an essential gene of the bacterial pathogen, which may explain why Bs2 confers the only effective field resistance to X.c . vesicatoria in pepper. Mol Gen Genet, 1990 Jul, 222(2-3), 452 - 6 Identification of a pathogenicity locus in Xanthomonas campestris pv . vesicatoria; Seal SE et al.; Mutants of a tomato strain of Xanthomonas campestris pv . vesicatoria (XCV), causal agent of bacterial spot of tomato and pepper, were produced using the transposon Tn5 carried in the suicide plasmid pGS9 . One prototrophic mutant, M461, was isolated which caused no visible reaction on tomato or pepper, but maintained the wild-type ability to induce a hypersensitive reaction (HR) on tobacco . This mutant showed similar growth characteristics to the wild-type in culture, but growth in planta was reduced . A genomic library of wild-type XCV was constructed in the broad host range cosmid vector pLAFR3 . Clone p6AD4 restored pathogenicity to M461 on tomato and the ability to induce a HR on pepper . This clone contained ca . 22 kb of XCV DNA . The insertion in M461 was in a site corresponding to a 1.1 kb EcoRI fragment of p6AD4. Mol Gen Genet, 1990 Jun, 222(1), 145 - 51 Use of oligonucleotide probes to identify members of two-component regulatory systems in Xanthomonas campestris pathovar campestris; Osbourn AE et al.; Two-component regulatory systems comprising a sensor and a regulator protein, both with highly conserved amino acid domains, and commonly genetically linked, have been described in a range of bacterial species and are involved in sensing environmental stimuli . We used two oligonucleotide probes matching the postulated coding regions for domains of sensor and regulator proteins respectively in Xanthomonas campestris pathovar campestris (Xcc) to identify possible two-component regulatory systems in Xcc . Two different fragments of Xcc DNA with homology to both of these probes were cloned . The DNA sequence of part of one of these fragments encompassed a potential open reading frame (ORF), the predicted amino acid sequence of which had extensive homology with regulator proteins of two-component regulatory systems . Analysis of the predicted amino acid sequence for the 3' end of an adjacent ORF revealed a very high level of homology with the C-terminal end of sensor proteins . Strains of Xcc with Tn5-induced mutations in the regulator gene were affected in extracellular polysaccharide production, and also in resistance to salt and chloramphenicol . No effects of mutation in the second clone were observed. Mol Gen Genet, 1990 Jun, 222(1), 157 - 60 Cloning of genes involved in negative regulation of production of extracellular enzymes and polysaccharide of Xanthomonas campestris pathovar campestris; Tang JL et al.; A recombinant plasmid pIJ3079 contains DNA sequences from Xanthomonas campestris pv campestris involved in coordinate negative regulation of production of the extracellular enzymes protease, endoglucanase, amylase and polygalacturonate lyase, and extracellular polysaccharide (EPS) . Wild-type bacteria harbouring pIJ3079 and therefore carrying extra copies of the gene(s) therein showed reduced enzyme and EPS production and reduced aggressiveness to plants . Localised Tn5 mutagenesis of the corresponding region of the genome gave mutants producing higher levels of enzymes and EPS than the wild type, suggesting that the gene(s) may negatively regulate production in the normal cell . Enzyme and EPS production in the mutants was still dependent on previously characterised positive regulatory genes. Lett Appl Microbiol, 1990 Jun, 10(6), 241 - 4 Production of monoclonal antibodies to Pseudomonas syringae pv . phaseolicola and Xanthomonas campestris pv . phaseoli; Wong WC; The production of monoclonal antibodies (MAbs) to ethylenediamine tetraacetic acid (sodium salt) soluble antigens of Pseudomonas syringae pv . phaseolicola and Xanthomonas campestris pv . phaseoli (fuscans strain) is described . MAbs A6-1 and A6-2 produced to Ps . syringae pv . phaseolicola are pathovar specific . Although MAb XP2 produced to X . campestris pv . phaseoli recognized surface antigens of all strains of this pathovar (including fuscans strains) it cross-reacted specifically with X . campestris pv . malvacearum; it did not react with any other known bacteria or unidentified epiphytes from navy bean seed or leaves . The isotype of both MAbs XP2 and A6-1 is IgG3 whereas that of MAb A6-2 is IgG2a . The reactive antigens are thermostable, but their chemical nature has not been determined. Zhonghua Min Guo Wei Sheng Wu Ji Mian Yi Xue Za Zhi, 1990 May, 23(2), 162 - 5 A simple method for maintaining Xanthomonas campestris pv . citri; Wu WC et al.; A typical colony of each of strains XW17, XW45, XW47, XW82, XW86, XW118, and XW138 of Xanthomonas campestris pv . citri was streaked onto nutrient agar, GY agar, minimal agar, and semi-enriched minimal agar plates, respectively . The agar plates, after incubated at 30 degrees C for 2-4 days, were inverted and stored at 4 degrees C in darkness . All of the X . campestris pv . citri strains retained their viability for at least 26 weeks on the semi-enriched minimal agar plates; whereas, cultures of these bacterial strains survived for only 2-10 weeks on the nutrient agar, 2-5 weeks on the GY agar plates and 12-26 weeks on the minimal agar plates . The bacterial strains which survived after 22-26 weeks on the semi-enriched minimal agar and minimal agar plates, respectively, also retained their ability to produce typical colonies and virulence . Thus, this semi-enriched minimal agar plate method is a simple and efficient way for maintaining the X . campestris pv . citri strains for a relatively long period. J Bacteriol, 1990 May, 172(5), 2804 - 7 Cloning and analysis of a 35.3-kilobase DNA region involved in exopolysaccharide production by Xanthomonas campestris pv . campestris; Hotte B et al.; Cosmid clones able to restore exopolysaccharide production in possibly insertion sequence element-induced surface mutants of Xanthomonas campestris pv . campestris were isolated . By fragment-specific Tn5-lac mutagenesis of one of the cosmids, pXCB1002, a new DNA region which is involved in exopolysaccharide biosynthesis and which is organized into at least 12 complementation groups was identified. Chin Med J (Engl), 1990 May, 103(5), 435 - 9 First isolation of Xanthomonas campestris from the blood of a Chinese woman; Li ZX et al.; Xanthomonas campestris isolated from the blood of a patient with a fever was first reported . Xanthomonas campestris is a bacterium that can cause black rot of some vegetables, such as rape . Chinese cabbage, etc . Human infection due to X . campestris has not been reported so far . The characteristics of this organism, including morphology, staining, physiology and biochemistry were studied . We believe that X . campestris is also one of the opportunistic pathogens, which can infect compromised host. Biotechnol Prog, 1990 May-Jun, 6(3), 182 - 7 Genetic engineering of polysaccharide structure: production of variants of xanthan gum in Xanthomonas campestris; Hassler RA et al.; Xanthan gum is an extracellular heteropolysaccharide produced by the bacterium Xanthomonas campestris . Xanthan has wide commercial application as a viscosifier of aqueous solutions . Previously, through genetic engineering, a set of mutants defective in the xanthan biosynthetic pathway has been obtained . Certain mutants were shown to synthesize and polymerize structural variants of the xanthan repeating unit and thus produce "variant xanthans" . Initial studies of solution viscosities of these polymers, presented here, indicate that the variants have rheological properties similar to, but not identical with, xanthan . These results indicate that acetylation and pyruvylation can affect the viscometric properties of xanthan . Specifically, the presence of pyruvate increases viscosity, whereas acetate decreases viscosity . In addition, the elimination of sugar residues from xanthan side chains also has a major effect on viscosity . Compared to wild-type xanthan, polymer lacking the terminal mannose (polytetramer) is a poor viscosifier . In contrast, polymer lacking both the terminal mannose and glucuronic acid (polytrimer) is a superior viscosifier, on a weight basis . There is a negative effect of acetylation on the viscosity of polytetramer xanthan, but there is seemingly no effect of acetylation on polytrimer xanthan viscosity . The further study of these materials should provide insight into the relationship between xanthan structure and rheological behavior. Gene, 1990 Apr 30, 89(1), 53 - 9 Nucleotide sequence of the engXCA gene encoding the major endoglucanase of Xanthomonas campestris pv . campestris; Gough CL et al.; The nucleotide sequence of the gene (engXCA) encoding the major extracellular endoglucanase (ENGXCA) of the phytopathogenic bacterium Xanthomonas campestris pv . campestris (X . c . campestris) was determined and compared with the N-terminal amino acid (aa) sequence of the purified enzyme . An open reading frame of 1479 bp encoding 493 aa was identified, of which the N-terminal 25 aa represent a potential signal peptide . Determination of the exact position of a Tn5 insertion within engXCA, which did not reduce the encoded enzyme activity, indicated that the C-terminal region of the protein is not crucial for ENGXCA activity . Comparison of the complete deduced aa sequence with those deduced from other endoglucanase- and exoglucanase-encoding genes revealed a region with a high degree of homology, located towards the C terminus of the protein . These data indicate that the X . c . campestris ENGXCA may have a domain structure similar to that of many other bacterial and fungal cellulolytic enzymes . Hydrophobic cluster analysis was performed on the deduced aa sequence . Comparison of this analysis with those of 30 other cellulase sequences belonging to six different families indicated that the X . c . campestris enzyme can be classified in family A . The two aa residues which had previously been identified as 'potentially catalytic' within this family of cellulases, are conserved in the X . c . campestris ENGXCA. Appl Environ Microbiol, 1990 Apr, 56(4), 919 - 23 Construction of lactose-utilizing Xanthomonas campestris and production of xanthan gum from whey; Fu JF et al.; Xanthomonas campestris pv . campestris possesses a low level of beta-galactosidase and therefore is not able to grow and produce significant amounts of xanthan gum in a medium containing lactose as the sole carbon source . In this study, a beta-galactosidase expression plasmid was constructed by ligating an X . campestris phage phi LO promoter with pKM005, a ColE1 replicon containing Escherichia coli lacZY genes and the lpp ribosome-binding site . It was then inserted into an IncP1 broad-host-range plasmid, pLT, and subsequently transferred by conjugation to X . campestris 17, where it was stably maintained . The lacZ gene under the control of the phage promoter was expressed at a high level, enabling the cells to grow in a medium containing lactose . Production of xanthan gum in lactose or diluted whey by the engineered strain was evaluated, and it was found to produce as much xanthan gum in these substrates as the cells did in a medium containing glucose. Int J Biol Macromol, 1990 Apr, 12(2), 71 - 8 Influence of acetyl and pyruvate substituents on the solution properties of xanthan polysaccharide; Shatwell KP et al.; Xanthan, an exocellular polysaccharide produced by the plant pathogenic bacterium Xanthomonas campestris has been the subject of considerable interest in recent years because of its unusual rheological properties in solution ('weak gel') and consequent range of applications . The polymer consists of a cellulosic backbone with trisaccharide side chains linked to alternate backbone residues; acetyl and pyruvate substituents are carried in variable amounts on these side chains . In this study a series of xanthans differing in the percentage of substituent groups and in molecular weight range have been prepared by culturing a variety of different strains of X . campestris . All of the xanthans have been characterized by a range of physicochemical techniques . In particular, the intrinsic viscosities at low shear rates, and at a range of ionic strengths, have been determined and the geometric persistence lengths evaluated by the Smidsrod-Haug method . Intensity light scattering measurements have been made using the procedure of Coviello and co-workers to promote molecular dispersion . Despite significant differences in the acetyl and pyruvate contents, the molecular weight vs mean square radius behaviour of our samples did not differ substantially from each other or from those reported for other xanthan samples in the literature . The persistence length, determined by the method of Schmidt et al . (120 +/- 8 nm) was also, within experimental error, the same for all the samples measured . These values differed considerably from those calculated from the ionic strength dependence of intrinsic viscosity (the Smidsrod-Haug method) was reported by Tinland and Rinaudo and calculated for our samples.(ABSTRACT TRUNCATED AT 250 WORDS) Infect Control Hosp Epidemiol, 1990 Mar, 11(3), 134 - 8 Nosocomial infection caused by Xanthomonas maltophilia: a case-control study of predisposing factors; Elting LS et al.; Factors predisposing to clinically significant nosocomial infection with Xanthomonas maltophilia were examined in a matched case-control study using multivariate techniques . Sixteen cases occurred among cancer patients in a six-month period, including an apparent cluster of three cases in an intensive care unit . These infections were unusually serious; eight patients had disseminated infection caused by X maltophilia and six died as a result of their infections . Among the 64 factors that were examined, therapy with broad-spectrum antibiotics and central venous catheterization were found to significantly increase susceptibility to infection . Therapy with imipenem was more than ten times more frequent among cases than among controls (p less than .001) . All fatal infections occurred in patients who had received imipenem, including two patients who died before the organism could be identified and appropriate therapy instituted . Infection with X maltophilia should be suspected in patients who develop superinfection while receiving imipenem, and prompt therapy should be instituted to improve chances of survival . Because a common environmental source of X maltophilia was not identified, further study is necessary to determine specific preventive measures. Mol Gen Genet, 1990 Feb, 220(3), 433 - 40 A multipurpose broad host range cloning vector and its use to characterise an extracellular protease gene of Xanthomonas campestris pathovar campestris; Liu YN et al.; A multipurpose broad host range plasmid, pIJ3200, was constructed by inserting the polylinker-containing 445 bp PvuII fragment of Bluescript M13 into the EcoRI site of the cosmid pLAFR1 . Using this vector a protease gene of Xanthomonas campestris pathovar campestris, previously cloned in the recombinant plasmid pIJ3070, was located by deletion to a 2.2 kb DNA region . Sequencing of the protease gene revealed an open reading frame encoding a 580 amino acid polypeptide with molecular weight of 57,000 . The deduced amino acid sequence showed strong homology with the subtilisin family of serine proteases . This, together with its sensitivity to inhibition by phenylmethylsulphonyl fluoride, suggests that the enzyme belongs to this family of proteases. Gene, 1990 Jan 31, 86(1), 123 - 8 The melanin operon of Streptomyces antibioticus: expression and use as a marker in gram-negative bacteria; Tseng HC et al.; The melC operon of Streptomyces antibioticus contains two genes, melC1 and melC2, necessary for the production of melanin pigment . We transferred the coding sequence of melC1 and melC2 to Escherichia coli plasmid pMTL23 such that its transcription was under the control of the lac promoter and melC1 was translationally fused to the lacZ alpha fragment . E . coli cultures containing this plasmid, pIF413, produced melanin after overnight incubation on 2YT agar supplemented with 0.1 mM CuCl2, 0.36 mM IPTG (or 0.2% lactose), and 2 mM tyrosine . Erwina carotovora could also be transformed by pIF413 to produce melanin . Two shuttle vectors were constructed: pLUS415 for E . coli and Streptomyces, and pLAF413 for E . coli and Xanthomonas campestris . These vectors confer melanin pigmentation in all the hosts that harbor them . The melC sequence provides the vectors with a convenient cloning marker for insertional or replacement inactivation. Eur J Biochem, 1990 Jan 26, 187(2), 381 - 6 Isolation and characterization of abaecin, a major antibacterial response peptide in the honeybee (Apis mellifera); Casteels P et al.; Honeybee (Apis mellifera) are frequently exposed to and likely to be infected by plant-associated bacteria . We mimicked this process by injecting bees with live bacteria and isolated five induced antibacterial substances by comparative liquid chromatographic mapping of the hemolymph . Three of these antibiotics belong to a unique family of small (18 amino acids) peptides: the apidaecins {Casteels et al . (1989) EMBO J . 8, 2387-2391} . We have now characterized a fourth bee immune response peptide . The complete sequence was established by Edman degradation of the peptide and fragments thereof . It is 34 amino acids long and contains 10 proline residues . The amino-terminal half is related to the apidaecins; similar proline motifs are also present in the amino-terminal quarter of the much longer fly diptericins . The newly identified peptide's broad spectrum, lower specific activities against Gram-negative plant pathogens and its inability to inhibit bacterial growth at medium ionic strength are different from the apidaecins . Moreover, the highest observed specific activity was against an apidaecin-resistant Xanthomonas strain . In contrast to the immediate action of apidaecins, bactericidal activity is delayed . We propose the name 'abaecin' for this new antibacterial response peptide. J Bacteriol, 1990 Jan, 172(1), 143 - 8 Characterization of IS476 and its role in bacterial spot disease of tomato and pepper; Kearney B et al.; IS476 is an endogenous insertion sequence present in copper-tolerant strains of Xanthomonas campestris pv . vesicatoria . Sequence analysis has revealed that the element is 1,225 base pairs in length, has 26-base-pair inverted repeats, and causes a 4-base-pair target site duplication upon insertion into the avirulence gene avrBs1 . Comparison of the full-length sequence with sequences in the National Biomedical Research Foundation and National Institutes of Health data bases showed that one of the predicted IS476 proteins is partially homologous to the putative transposase of IS3 from Escherichia coli, and the inverted repeats of IS476 have significant homology to the inverted repeats of the IS51 insertion sequence of Pseudomonas syringae pv . savastanoi . A transposition assay based on the insertional inactivation of the sacRB locus of Bacillus subtilis was used to demonstrate that one of the three copies of IS476 residing on the 200-kilobase copper plasmid pXVCU1 is capable of transposition in several strains of Xanthomonas campestris . The position of IS476 insertion in several avrBs1 mutants was established and was shown to influence both induction of hypersensitivity and bacterial growth in planta. J Antibiot (Tokyo), 1989 Nov, 42(11), 1556 - 61 Altemicidin, a new acaricidal and antitumor substance . I . Taxonomy, fermentation, isolation and physico-chemical and biological properties; Takahashi A et al.; Screening of new insecticidal and acaricidal antibiotics was carried out with reference to anti-brine shrimp activity from actinomycete strains isolated from marine environments . Of 200 actinomycete isolates, one isolate was found to produce a new substance, altemicidin . The strain was isolated from sea mud collected at Gamo, Miyagi Prefecture, Japan, and identified as Streptomyces sioyaensis SA-1758 . Altemicidin was purified by Diaion CHP-20P and Sephadex LH-20 column chromatographies . The molecular formula was determined as C13H20N4O7S by elemental analysis, MS and 13C NMR spectrum . Altemicidin showed not only acaricidal activity but also antitumor activity . The compound showed no antimicrobial activity except the inhibitory activity to Xanthomonas strains. J Antimicrob Chemother, 1989 Sep, 24 Suppl A, 85 - 99 Bacteriostatic and bactericidal in-vitro activity of meropenem against clinical isolates, including Mycobacterium avium complex; Inderlied CB et al.; For clinical isolates the MICs of meropenem were significantly lower than the MICs of imipenem, especially against Pseudomonas aeruginosa . Furthermore, meropenem was bactericidal for Pseudomonas spp., including Ps . (Xanthomonas) maltophilia, and staphylococci, with MBCs on average only two-fold above the respective MICs . The bactericidal activity was confirmed by killing curve assays . Strains with high meropenem MICs (greater than or equal to 8 mg/l) were killed by a combination of the carbapenem and amikacin, with kinetics that indicated synergism between the two antimicrobial agents. J Antimicrob Chemother, 1989 Sep, 24 Suppl A, 187 - 96 Meropenem: activity against resistant gram-negative bacteria and interactions with beta-lactamases; Sanders CC et al.; The activity of meropenem, a new carbapenem, was determined against 82 Gram-negative bacteria in agar dilution tests . Many of these isolates were resistant to one or more beta-lactam antibiotics and the mechanisms responsible for the resistance had been characterized . The production of beta-lactamases had little influence on susceptibility to either meropenem or imipenem except in tests with Aeromonas hydrophila and Pseudomonas (Xanthomonas) maltophilia . These species produced metalloenzymes capable of hydrolyzing the carbapenems, and strains expressing high levels of these enzymes were resistant to both meropenem and imipenem . Clinical isolates of P . aeruginosa that had developed resistance to imipenem during therapy with the drug were two- to 32-fold less susceptible to meropenem than the corresponding pretreatment isolates . Alterations in outer membrane proteins were associated with this change in susceptibility to the carbapenems . Meropenem was a less potent inducer of Class I beta-lactamases than imipenem but was still a better inducer than ceftazidime or piperacillin . Overall, meropenem showed excellent activity against bacteria producing a variety of beta-lactamases, but cross-resistance between meropenem and imipenem due to enzymatic and non-enzymatic mechanisms did occur. Mayo Clin Proc, 1989 Sep, 64(9), 1097 - 104 Xanthomonas maltophilia: an emerging nosocomial pathogen; Marshall WF et al.; Xanthomonas maltophilia is a potentially pathogenic organism with a broad clinical spectrum . Nosocomial colonization and infection are the most common manifestations . The incidence of clinical isolation of X . maltophilia is on the rise, possibly in part because of the selective pressure from the new antimicrobial agents to which it is resistant . The organism is usually resistant to commonly used antimicrobial agents, including most cephalosporins, aztreonam, antipseudomonal penicillins, imipenem, and the quinolones. J Antimicrob Chemother, 1989 Sep, 24 Suppl A, 1 - 7 The carbapenems: new broad spectrum beta-lactam antibiotics; Moellering RC Jr et al.; The carbapenems differ from the penicillins (penams) in having an unsaturated bond between C2 and C3 and a carbon atom replacing sulphur at position 1 of the thiazolidine ring . The various carbapenems differ primarily in the configuration of the side chains at C2 and C6 . Carbapenems include the thienamycins, olivanic acids, carpetimycins, asparenomycins, pluracidomycins, and other natural and semi-synthetic compounds . Carbapenems vary in their stability and resistance to beta-lactamases, ability to inhibit and to induce beta-lactamases, and in-vitro spectra of activity . Many are highly unstable in solution . Some are degraded by mammalian dehydropeptidases in vivo . The hydroxyethyl side chain in the alpha or trans-configuration at C6 in thienamycin provides striking resistance to beta-lactamases, but this compound is highly unstable in concentrated solution and the solid state . The N-formimidoyl derivative of thienamycin (imipenem) is more stable in solution and has broad-spectrum activity against aerobic and anaerobic bacteria . However, imipenem is not stable to renal dehydropeptidases and its degradation products are nephrotoxic in certain animals . It is thus administered with the dehydropeptidase inhibitor cilastatin . High serum levels of imipenem (especially in patients with renal failure and central nervous system disease) have been associated with seizures . The drug is therefore not appropriate for meningitis . Meropenem is a new carbapenem which has the same side chain as imipenem at C6 . Its unique side chain at C2 assures a broad spectrum of activity which includes Pseudomonas aeruginosa and other aerobic and anaerobic organisms . Only Ps . (Xanthomonas) maltophilia is generally resistant . This species is resistant also to imipenem.(ABSTRACT TRUNCATED AT 250 WORDS) Zhonghua Min Guo Wei Sheng Wu Ji Mian Yi Xue Za Zhi, 1989 Aug, 22(3), 151 - 62 Identification and nucleotide sequence of attachment site of the Cflt filamentous phage from Xanthomonas campestris pv . citri; Fann JH et al.; It has been reported that the attachment site on the phage attP is located from 69.2 to 73.8 min on Cflt RF DNA . KpnI and PstI were used, which cut respectively at 67.2 and 72.6 min of Cflt RF DNA . A 0.54 kb fragment containing attP was obtained . For isolation of the right (attR) and left (attL) junctions of prophage and host chromosomal DNA, lysogen DNA was digested with HindIII and used to prepare a recombinant plasmid library . With Cflt RF DNA as a probe, three types of recombinant plasmids respectively containing inserts of 1.7, 4.3 and 2.8 kb DNA fragments were obtained . Since 1.7 kb represents the internal HindIII fragment of Cflt, 2.8 kb were from the junctional regions of prophage and host chromosomal DNA . Further analysis of restriction fragment patterns suggested that the 2.8 kb fragment contains attR, while the 4.3 kb fragment contains attL . To isolate the attachment site on the host bacteria (attB), recombinant plasmids constructed from HindIII DNA fragments of uninfected cells are screened by using molecular probes prepared from the host DNA sequences immediately adjacent to the prophage in the lysogenic host chromosomal DNA . A 1.45 kb fragment was obtained . Further analysis with HindIII site on this fragment established that it represents attB . The DNA nucleotide sequences of attP, attB attR and attL were determined . All of them contain a common 15 nucleotide core with the sequence of 5'-TATACATTATGCGAA-3' . The common core region of the recombination site shows two inverted-repeat DNA sequence. ASAIO Trans, 1989 Jul-Sep, 35(3), 314 - 6 Recovery of bacteria from reprocessed high flux dialyzers after bacterial contamination of the header spaces and O-rings; Bland LA et al.; The Centers for Disease Control (CDC) have received reports of bacteremia in patients on high flux dialysis attributed to contamination of dialyzer header spaces or o-rings . A study was performed in which header spaces and o-rings of Hemoflow F-80 dialyzers (Fresenius AG, Bad Homburg, FRG) were exposed to an aqueous suspension of Xanthomonas maltophilia and Mycobacterium chelonae for 1 hour . After exposure, the dialyzers were reprocessed manually with 4% formaldehyde, 4% Renalin, 2.5% Renalin, or sterile water (SW) as a control, or with an automated reprocessing machine using 3.25% Renalin . After 48 hours the blood compartment (BC) was drained and rinsed twice with 500 ml of SW . Each BC sample was cultured . To simulate dialysis, separate circulates of SW were pumped through the DC and the BC . After 15 minutes, the BC circulate was cultured, headers were unscrewed, and o-rings, header caps, and fiber bundle ends were cultured . For each germicide, bacteria were recovered in low numbers, primarily from the o-rings and the o-ring groove in the header caps . In 38 tests, a total of 60 of 342 assays (17.5%) were positive . In only one of these tests one bacterial colony forming unit (cfu) was recovered from the BC circulate during simulated dialysis . It was concluded that if header spaces and o-rings are contaminated, bacteria could be sealed protectively from the germicide . However, concentrations of surviving bacteria were low, probably outside the BC, and did not effectively contaminate the BC circulate during simulated dialysis. Mol Gen Genet, 1989 Jul, 218(1), 127 - 36 Genetic and structural characterization of the avirulence gene avrBs3 from Xanthomonas campestris pv . vesicatoria; Bonas U et al.; The avirulence gene avrBs3 from Xanthomonas campestris pv . vesicatoria was cloned and found to be localized on a self-transmissable plasmid . Genetic analysis of an avrBs3 insertion mutation revealed that avrBs3 constitutes a single locus, specifying the resistant phenotype on pepper plants . Southern blot experiments showed that no DNA sequences homologous to avrBs3 were present in other races of X . c . pv . vesicatoria, which are unable to induce a hypersensitive reaction on ECW-30R . However, the DNA of several different pathovars of X . campestris hybridized to the avrBs3 probe . A deletion analysis defined a region of 3.6-3.7 kb essential for avrBs3 activity . The nucleotide sequence of this region was determined . A 3561 nucleotide open reading frame (ORF1), encoding a 125,000 dalton protein, was found in the 3.7 kb region that was sufficient for avrBs3 activity . A second long ORF (2351 nucleotides) was identified on the other strand . A remarkable feature of both ORFs is the presence of 17 direct repeats of 102 bp which share 91%-100% homology with each other. Int J Biol Macromol, 1989 Jun, 11(3), 137 - 44 Long-term storage of xanthan in seawater at elevated t