| bioaugmentation of activated sludge by an indigenous 3-chloroaniline-degrading comamonas testosteroni strain, i2gfp. | a strain identified as comamonas testosteroni i2 was isolated from activated sludge and found to be able to mineralize 3-chloroaniline (3-ca). during the mineralization, a yellow intermediate accumulated temporarily, due to the distal meta-cleavage of chlorocatechol. this strain was tested for its ability to clean wastewater containing 3-ca upon inoculation into activated sludge. to monitor its survival, the strain was chromosomally marked with the gfp gene and designated i2gfp. after inoculatio ... | 2000 | 10877785 |
| molecular analysis of surfactant-driven microbial population shifts in hydrocarbon-contaminated soil. | we analyzed the impact of surfactant addition on hydrocarbon mineralization kinetics and the associated population shifts of hydrocarbon-degrading microorganisms in soil. a mixture of radiolabeled hexadecane and phenanthrene was added to batch soil vessels. witconol sn70 (a nonionic, alcohol ethoxylate) was added in concentrations that bracketed the critical micelle concentration (cmc) in soil (cmc') (determined to be 13 mg g(-1)). addition of the surfactant at a concentration below the cmc' (2 ... | 2000 | 10877792 |
| variation among strains of xanthomonas campestris pv. vasculorum from mauritius and other countries based on fatty acid analysis. | fatty acid profiling was used to study variation amongst strains of xanthomonas campestris pv. vasculorum (xcv). they could be divided into five groups using cellular fatty acid profiles. group a strains represent a new and little known taxon and all came from plants of broom bamboo (thysanolaena maxima) from mauritius. group b strains included the xcv pathotype reference strain and were from palms, broom bamboo and sugarcane from mauritius, reunion and australia. group c contained southern afri ... | 2000 | 10879989 |
| cultivar-specific avirulence and virulence functions assigned to avrpphf in pseudomonas syringae pv. phaseolicola, the cause of bean halo-blight disease. | the avrpphf gene was cloned from pseudomonas syringae pathovar phaseolicola (pph:) races 5 and 7, based on its ability to confer avirulence towards bean cultivars carrying the r1 gene for halo-blight resistance, such as red mexican. avrpphf comprised two open reading frames, which were both required for function, and was located on a 154 kb plasmid (pav511) in pph: strain rw60 of pph:, lacking pav511, displayed a loss in virulence to a range of previously susceptible cultivars such as tendergree ... | 2000 | 10880434 |
| [major-polygene effect analysis of resistance to bacterial blight (xanthomonas campestris pv. oryzae) in rice]. | five crosses between resistance and susceptible were analyzed to study major-polygene effect using major-polygene mixed mode. the result showed that 3 of 5 crosses were controlled by both major gene and polygene. in addition, there were large variation of additive effect, variance as well as heredity of major gene polygene in 3 crosses. major gene was predominant in resistant variation, but durability should be considered. we suggested that construct major-polygene system be constructed in the l ... | 2000 | 10883537 |
| enhancement of induced disease resistance by simultaneous activation of salicylate- and jasmonate-dependent defense pathways in arabidopsis thaliana. | the plant-signaling molecules salicylic acid (sa) and jasmonic acid (ja) play an important role in induced disease resistance pathways. cross-talk between sa- and ja-dependent pathways can result in inhibition of ja-mediated defense responses. we investigated possible antagonistic interactions between the sa-dependent systemic acquired resistance (sar) pathway, which is induced upon pathogen infection, and the ja-dependent induced systemic resistance (isr) pathway, which is triggered by nonpatho ... | 2000 | 10890883 |
| sequence and molecular analysis of the rpoa cluster genes from xanthomonas campestris pv. campestris. | the xanthomonas campestris rpsm (s13)-rpsk (s11)-rpsd (s4)-rpoa (alpha)-rplq (l17) cluster, encoding rna polymerase alpha-subunit and four ribosomal proteins, reside in a 3164-bp dna region. the n-terminal sequence of the authentic alpha-protein determined chemically matches that predicted from the nucleotide sequence. rplq is monocistronic, instead of being co-transcribed with the other genes as in escherichia coli. antiserum against the his-tagged alpha-protein cross-reacted with the e. coli a ... | 2000 | 10899600 |
| requirement of the pseudomonas aeruginosa tonb gene for high-affinity iron acquisition and infection. | to investigate the contribution of the tonb protein to high-affinity iron acquisition in pseudomonas aeruginosa, we constructed tonb-inactivated mutants from strain pao1 and its derivative deficient in producing the siderophores pyoverdin and pyochelin. the tonb mutants could not grow in a free-iron-restricted medium prepared by apotransferrin addition, even though the medium was supplemented with each purified siderophore or with a heme source (hemoglobin or hemin). the tonb inactivation was sh ... | 2000 | 10899848 |
| role of phosphoglucomutase of bordetella bronchiseptica in lipopolysaccharide biosynthesis and virulence. | the phosphoglucomutase (pgm)-encoding gene of bordetella bronchiseptica is required for lipopolysaccharide (lps) biosynthesis. an insertion mutant of the wild-type b. bronchiseptica strain bb7865 which disrupted lps biosynthesis was created and characterized (bb7865pgm). genetic analysis of the mutated gene showed it shares high identity with pgm genes of various bacterial species and forms part of an operon which also encompasses the gene encoding phosphoglucose isomerase. functional assays for ... | 2000 | 10899872 |
| a protease-resistant catalase, kata, released upon cell lysis during stationary phase is essential for aerobic survival of a pseudomonas aeruginosa oxyr mutant at low cell densities. | a pseudomonas aeruginosa oxyr mutant was dramatically sensitive to h(2)o(2), despite possessing wild-type catalase activity. oxygen-dependent oxyr phenotypes also included an inability to survive aerobic serial dilution in luria broth and to resist aminoglycosides. plating the oxyr mutant after serial dilution in its own spent culture supernatant, which contained the major catalase kata, or under anaerobic conditions allowed for survival. kata was resistant to sodium dodecyl sulfate, proteinase ... | 2000 | 10913089 |
| novel insertion sequence elements associated with genetic heterogeneity and phenotype conversion in ralstonia solanacearum. | three insertion sequences (is) elements were isolated from the phytopathogen ralstonia solanacearum. southern hybridization using these is elements as probes revealed hybridization profiles that varied greatly between different strains of the pathogen. during a spontaneous phenotype conversion event, the promoter of the phca gene was interrupted by one of these is elements. | 2000 | 10913109 |
| effect of field inoculation with sinorhizobium meliloti l33 on the composition of bacterial communities in rhizospheres of a target plant (medicago sativa) and a non-target plant (chenopodium album)-linking of 16s rrna gene-based single-strand conformation polymorphism community profiles to the diversity of cultivated bacteria. | fourteen weeks after field release of luciferase gene-tagged sinorhizobium meliloti l33 in field plots seeded with medicago sativa, we found that the inoculant also occurred in bulk soil from noninoculated control plots. in rhizospheres of m. sativa plants, s. meliloti l33 could be detected in noninoculated plots 12 weeks after inoculation, indicating that growth in the rhizosphere preceded spread into bulk soil. to determine whether inoculation affected bacterial diversity, 1,119 bacteria were ... | 2000 | 10919821 |
| pseudomonas syringae hrp type iii secretion system and effector proteins. | pseudomonas syringae is a member of an important group of gram-negative bacterial pathogens of plants and animals that depend on a type iii secretion system to inject virulence effector proteins into host cells. in p. syringae, hrp/hrc genes encode the hrp (type iii secretion) system, and avirulence (avr) and hrp-dependent outer protein (hop) genes encode effector proteins. the hrp/hrc genes of p. syringae pv syringae 61, p. syringae pv syringae b728a, and p. syringae pv tomato dc3000 are flanke ... | 2000 | 10922033 |
| molecular and cell biology aspects of plague. | a 70-kb virulence plasmid (sometimes called pyv) enables yersinia spp. to survive and multiply in the lymphoid tissues of their host. it encodes the yop virulon, a system consisting of secreted proteins called yops and their dedicated type iii secretion apparatus called ysc. the ysc apparatus forms a channel composed of 29 proteins. of these, 10 have counterparts in almost every type iii system. secretion of some yops requires the assistance, in the bacterial cytosol, of small individual chapero ... | 2000 | 10922034 |
| parameters affecting gene expression from the pm promoter in gram-negative bacteria. | the pm promoter inserted chromosomally or in broad-host-range replicons based on plasmid rsf1010 or rk2 are useful systems for both high- and low-level expression of cloned genes in several gram-negative bacterial species. the positive pm regulator xyls is activated by certain substituted benzoic acid derivatives, and here we show that these effectors induce expression of pm at similar relative ranking levels in both escherichia coli and pseudomonas aeruginosa however, the kinetics of expression ... | 2000 | 10935724 |
| genomic and phenotypic characterization of xanthomonas cynarae sp. nov., a new species that causes bacterial bract spot of artichoke (cynara scolymus l.). | a bacterial disease of artichoke (cynara scolymus l.) was first observed in 1954 in brittany and the loire valley, france. this disease causes water-soaked spots on bracts and depreciates marketability of the harvest. ten strains of the pathogen causing bacterial spot of artichoke, previously identified as a member of the genus xanthomonas, were characterized and compared with type and pathotype strains of the 20 xanthomonas species using a polyphasic study including both phenotypic and genomic ... | 2000 | 10939652 |
| stationary-phase variation due to transposition of novel insertion elements in xanthomonas oryzae pv. oryzae. | xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. spontaneous mutants which are deficient for virulence and extracellular polysaccharide (eps) production accumulate in large numbers in stationary-phase cultures of this bacterium, a phenomenon which we have called stationary-phase variation. a clone (psd1) carrying the eps biosynthetic gene (gum) cluster of x. oryzae pv. oryzae restored eps production and virulence to several spv (for stationary-phase variatio ... | 2000 | 10940020 |
| evaluation of xanthomonas campestris survival in a soil microcosm system. | xanthomonas campestris pv. campestris is a pathogen of cruciferous plants. we studied the survival of the wild type strain and mutant derivatives which are deficient in exopolysaccharide (eps) or in extracellular protease synthesis in soil microcosms in order to test the hypothesis that, in this environment, adherence to soil particles and scavenging of nutrients are very important strategies for bacterial survival. in sterile soil microcosms, differences in survival were only observed between t ... | 1999 | 10943401 |
| modified pyrogallol-initiated immunogold-silver enhancement technique applicable to prokaryotes. | a modified immunogold-silver enhancement technique that was designed to reduce the nonspecific granular background staining, particularly for application on prokaryotic organisms, is reported. aerial oxidation of pyrogallol contained in the commercial silver enhancer solution was effectively controlled during storage and in the reaction mixture. a combination of strategies such as storing the reagent under argon, modifying it using 0.5% (w/v) anhydrous sodium sulfite, reducing the concentration ... | 2000 | 10958966 |
| the redox-sensitive transcriptional activator oxyr regulates the peroxide response regulon in the obligate anaerobe bacteroides fragilis. | the peroxide response-inducible genes ahpcf, dps, and katb in the obligate anaerobe bacteroides fragilis are controlled by the redox-sensitive transcriptional activator oxyr. this is the first functional oxidative stress regulator identified and characterized in anaerobic bacteria. oxyr and dps were found to be divergently transcribed, with an overlap in their respective promoter regulatory regions. b. fragilis oxyr and dps proteins showed high identity to homologues from a closely related anaer ... | 2000 | 10960088 |
| characterization of the incw cryptic plasmid pxv2 from xanthomonas campestris pv. vesicatoria. | the gram-negative plant pathogen xanthomonas campestris pv. vesicatoria strain xv2 harbors an indigenous, cryptic plasmid pxv2 of 14.6 kb. this plasmid can only be maintained in xanthomonas and is incapable of self-transmission. however, incompatibility testing classified it in incw, a group containing the smallest number of naturally occurring, broad-host-range, conjugative plasmids. a pxv2 derivative containing only a 5.5-kb psti fragment is stably maintained. deletion of a 3.0-kb region from ... | 2000 | 10964626 |
| a serine protease-encoding gene (aprii) of alteromonas sp. strain o-7 is regulated by the iron uptake regulator (fur) protein. | the ferric uptake regulator (fur) box-like sequence was located upstream of the serine protease-encoding gene (aprii) from a marine bacterium, alteromonas sp. strain o-7. to clarify whether the production of aprii (the gene product of aprii) is regulated by the environmental iron concentrations, this strain was cultured under iron-depleted or iron-rich conditions and the level of aprii in the culture supernatant was analyzed by western blotting. the production of aprii was significantly represse ... | 2000 | 10966390 |
| starvation improves survival of bacteria introduced into activated sludge. | a phenol-degrading bacterium, ralstonia eutropha e2, was grown in luria-bertani (lb) medium or in an inorganic medium (called mp) supplemented with phenol and harvested at the late-exponential-growth phase. phenol-acclimated activated sludge was inoculated with the e2 cells immediately after harvest or after starvation in mp for 2 or 7 days. the densities of the e2 populations in the activated sludge were then monitored by quantitative pcr. the e2 cells grown on phenol and starved for 2 days (p- ... | 2000 | 10966407 |
| a novel gene encoding xanthan lyase of paenibacillus alginolyticus strain xl-1. | xanthan-modifying enzymes are powerful tools in studying structure-function relationships of this polysaccharide. one of these modifying enzymes is xanthan lyase, which removes the terminal side chain residue of xanthan. in this paper, the cloning and sequencing of the first xanthan lyase-encoding gene is described, i. e., the xala gene, encoding pyruvated mannose-specific xanthan lyase of paenibacillus alginolyticus xl-1. the xala gene encoded a 100, 823-da protein, including a 36-amino-acid si ... | 2000 | 10966413 |
| phylogenetic analysis of bacterial communities in mesophilic and thermophilic bioreactors treating pharmaceutical wastewater. | the phylogenetic diversity of the bacterial communities supported by a seven-stage, full-scale biological wastewater treatment plant was studied. these reactors were operated at both mesophilic (28 to 32 degrees c) and thermophilic (50 to 58 degrees c) temperatures. community fingerprint analysis by denaturing gradient gel electrophoresis (dgge) of the pcr-amplified v3 region of the 16s rrna gene from the domain bacteria revealed that these seven reactors supported three distinct microbial commu ... | 2000 | 10966414 |
| exposure of phytopathogenic xanthomonas spp. to lethal concentrations of multiple oxidants affects bacterial survival in a complex manner. | during plant-microbe interactions and in the environment, xanthomonas campestris pv. phaseoli is likely to be exposed to high concentrations of multiple oxidants. here, we show that simultaneous exposures of the bacteria to multiple oxidants affects cell survival in a complex manner. a superoxide generator (menadione) enhanced the lethal effect of an organic peroxide (tert-butyl hydroperoxide) by 1, 000-fold; conversely, treatment of cells with menadione plus h(2)o(2) resulted in 100-fold protec ... | 2000 | 10966423 |
| effect of oxygen on formation and structure of azotobacter vinelandii alginate and its role in protecting nitrogenase. | the activity of nitrogenase in the nitrogen-fixing bacterium azotobacter vinelandii grown diazotrophically under aerobic conditions is generally considered to be protected against o(2) by a high respiration rate. in this work, we have shown that a high rate of respiration is not the prevailing mechanism for nitrogenase protection in a. vinelandii grown in phosphate-limited nitrogen-free chemostat culture. instead, the formation of alginate appeared to play a decisive role in protecting the nitro ... | 2000 | 10966426 |
| dna-based diagnostic approaches for identification of burkholderia cepacia complex, burkholderia vietnamiensis, burkholderia multivorans, burkholderia stabilis, and burkholderia cepacia genomovars i and iii. | bacteria of the burkholderia cepacia complex consist of five discrete genomic species, including genomovars i and iii and three new species: burkholderia multivorans (formerly genomovar ii), burkholderia stabilis (formerly genomovar iv), and burkholderia vietnamiensis (formerly genomovar v). strains of all five genomovars are capable of causing opportunistic human infection, and microbiological identification of these closely related species is difficult. the 16s rrna gene (16s rdna) and reca ge ... | 2000 | 10970351 |
| bacteria in the leaf ecosystem with emphasis on pseudomonas syringae-a pathogen, ice nucleus, and epiphyte. | the extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. this review focuses on the bacterial component of leaf microbial communities, with emphasis on pseudomonas syringae-a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. among the diversity of bacteria that colonize leaves, none has received wider attention than p. syringae, as it gained notoriety for being the firs ... | 2000 | 10974129 |
| [xanthan production by xanthomonas campestris in a non-conventional culture medium]. | among 3 varieties of xanthomonas campestris, the variety ocumo (x. campestris pv. ocumo), showed the greatest capacity for producing xanthan. this bacteria grows appropriately and produces this polysaccharide in a wide diversity of carbohydrate sources. however, this strain does not produce xanthan when the carbohydrate comes from lignocellulosic materials. the glucose syrup favepro was the carbon source that showed the best yield (23 g/l) with the greatest viscosity (7000 cps) of xanthan. the o ... | 1999 | 10974710 |
| resistance of tomato and pepper to t3 strains of xanthomonas campestris pv. vesicatoria is specified by a plant-inducible avirulence gene. | tomato race 3 (t3) of xanthomonas campestris pv. vesicatoria (xcv) elicits a hypersensitive response (hr) in leaves of lycopersicon esculentum near-isogenic line (nil) 216 and pepper genotypes. one cosmid clone (35 kb) selected from a genomic library of a t3 strain induced an hr in all resistant plants. a 1.5-kb active subclone containing the putative avirulence (avr) gene, designated avrxv3, was sequenced. the avrxv3 gene encodes a 654-bp open reading frame (orf) with no homology to any known g ... | 2000 | 10975648 |
| in vitro antimicrobial properties of recombinant asabf, an antimicrobial peptide isolated from the nematode ascaris suum. | asabf is a csalphabeta-type antimicrobial peptide that contains four intramolecular disulfide bridges (y. kato and s. komatsu, j. biol. chem. 271:30493-30498, 1996). in the present study, a recombinant asabf was produced by using a yeast expression system, and its antimicrobial activity was characterized in detail. the recombinant asabf was active against all gram-positive bacteria tested (7 of 7; minimum bactericidal concentration [mbc], 0.03 to 1 microg/ml) except leuconostoc mesenteroides, so ... | 2000 | 10991847 |
| molecular and physiological analysis of an oxyr-regulated ahpc promoter in xanthomonas campestris pv. phaseoli. | in xanthomonas campestris pv. phaseoli, a gene for the alkyl hydroperoxide reductase subunit c (ahpc) had unique patterns of regulation by various forms of oxyr. reduced oxyr repressed expression of the gene, whereas oxidized oxyr activated its expression. this dual regulation of ahpc is unique and unlike all other oxyr-regulated genes. the ahpc transcription start site was determined. analysis of the region upstream of the site revealed promoter sequences that had high homology to the xanthomon ... | 2000 | 10998180 |
| identification of essential amino acids in the bacterial alpha -mannosyltransferase acea. | the alpha-mannosyltransferase acea from acetobacter xylinum belongs to the cazy family 4 of retaining glycosyltransferases. we have identified a series of either highly conserved or invariant residues that are found in all family 4 enzymes as well as other retaining glycosyltransferases. these residues included glu-287 and glu-295, which comprise an ex(7)e motif and have been proposed to be involved in catalysis. alanine replacements of each conserved residue were constructed by site-directed mu ... | 2000 | 11001941 |
| leafy gall formation is controlled by fasr, an arac-type regulatory gene in rhodococcus fascians. | rhodococcus fascians can interact with many plant species and induce the formation of either leafy galls or fasciations. to provoke symptoms, r. fascians strain d188 requires pathogenicity genes that are located on a linear plasmid, pfid188. the fas genes are essential for virulence and constitute an operon that encodes, among other functions, a cytokinin synthase gene. expression of the fas genes is induced by extracts of infected plant tissue only. we have isolated an arac-type regulatory gene ... | 2000 | 11004184 |
| identification of a copper-responsive two-component system on the chromosome of escherichia coli k-12. | using a genetic screen we have identified two chromosomal genes, cusrs (ylca ybcz), from escherichia coli k-12 that encode a two-component, signal transduction system that is responsive to copper ions. this regulatory system is required for copper-induced expression of pcoe, a plasmid-borne gene from the e. coli copper resistance operon pco. the closest homologs of cusr and cuss are plasmid-borne two-component systems that are also involved in metal responsive gene regulation: pcor and pcos from ... | 2000 | 11004187 |
| pcr assays that identify the grapevine dieback fungus eutypa lata. | eutypa lata is the causal fungal agent of eutypa dieback, a serious grapevine necrotic disease. the erratic and delayed (1 to 2 months) appearance of characteristic conidia on culture media and the presence of numerous microorganisms in decaying wood make it difficult either to identify or to detect e. lata in grapevine wood samples. we designed six pairs of pcr primers for diagnosis of e. lata. three primer pairs were derived from ribosomal dna internal transcribed spacer sequences, and three p ... | 2000 | 11010901 |
| pepper gene encoding a basic class ii chitinase is inducible by pathogen and ethephon. | a chitinase cdna clone (designated cachi2) was isolated from the cdna library of pepper leaves infected with xanthomonas campestris pv. vesicatoria. the 1004-bp full-length cachi2 cdna encodes a basic chitinase with an n-terminal 24 amino acid signal peptide followed by a catalytic region. an analysis of its sequence indicates that cachi2 is a class ii chitinase, because it does not have chitin-binding domain and c-terminal extension sequences. the deduced amino acid sequence of cachi2 has a hig ... | 2000 | 11011091 |
| pepper gene encoding a basic beta-1,3-glucanase is differentially expressed in pepper tissues upon pathogen infection and ethephon or methyl jasmonate treatment. | a basic beta-1,3-glucanase cdna clone (cabglu) was isolated from the cdna library constructed from hypersensitive response lesions of pepper leaves infected with avirulent strain of xanthomonas campestris pv. vesicatoria. the deduced polypeptide of cabglu which contains a c-terminal extension n-glycosylated at a single site characterized as typical structure of class i beta-1,3-glucanase has a high level of identity with tobacco basic beta-1,3-glucanase (77.4%), but only a moderate level of iden ... | 2000 | 11011097 |
| intracellular glucosaminidase of the bacterium xanthomonas campestris ibpm b-124: purification and properties. | a system of intracellular autolytic enzymes of the bacterium xanthomonas campestris ibpm b-124 was found to include enzymes with muramidase and glucosaminidase activities, while a system of extracellular bacteriolytic enzymes of the same bacterium includes muramidase, muramoylalanine amidase, and endopeptidase. using a purification technique including fractional precipitation with ammonium sulfate, gel-filtration on toyopearl hw-55f, and fplc ion-exchange chromatography on mono q, a preparation ... | 2000 | 11042495 |
| o-specific polysaccharide structure of the aqueous lipopolysaccharide fraction from xanthomonas campestris pv. vitians strain 1839. | the structure of xanthomonas campestris pv. vitians o-specific polysaccharide of the lipopolysaccharide fraction, extracted from the aqueous phase, was defined, on the basis of chemical and spectroscopical methods, as constituted by the following repeating unit: [--> 3)-alpha-l-rhap-(1 -->]n 3)-beta-l-rhap-(1 --> where n is more frequently equal to 2, but it also assumes values equal to 1 and to 3. | 2000 | 11072852 |
| s-adenosylmethionine decarboxylase from the archaeon methanococcus jannaschii: identification of a novel family of pyruvoyl enzymes. | polyamines are present in high concentrations in archaea, yet little is known about their synthesis, except by extrapolation from bacterial and eucaryal systems. s-adenosylmethionine (adomet) decarboxylase, a pyruvoyl group-containing enzyme that is required for spermidine biosynthesis, has been previously identified in eucarya and escherichia coli. despite spermidine concentrations in the methanococcales that are several times higher than in e. coli, no adomet decarboxylase gene was recognized ... | 2000 | 11073910 |
| a xanthomonas alkyl hydroperoxide reductase subunit c (ahpc) mutant showed an altered peroxide stress response and complex regulation of the compensatory response of peroxide detoxification enzymes. | alkyl hydroperoxide reductase subunit c (ahpc) is the catalytic subunit responsible for alkyl peroxide metabolism. a xanthomonas ahpc mutant was constructed. the mutant had increased sensitivity to organic peroxide killing, but was unexpectedly hyperresistant to h(2)o(2) killing. analysis of peroxide detoxification enzymes in this mutant revealed differential alteration in catalase activities in that its bifunctional catalase-peroxidase enzyme and major monofunctional catalase (kat1) increased s ... | 2000 | 11073935 |
| molecular signals required for type iii secretion and translocation of the xanthomonas campestris avrbs2 protein to pepper plants. | strains of xanthomonas campestris pv. vesicatoria (xcv) carrying avrbs2 are specifically recognized by bs2 pepper plants, resulting in localized cell death and plant resistance. agrobacterium-mediated transient expression of the xcv avrbs2 gene in plant cells results in bs2-dependent cell death, indicating that the avrbs2 protein alone is sufficient for the activation of disease resistance-mediated cell death in planta. we now provide evidence that avrbs2 is secreted from xcv and that secretion ... | 2000 | 11078519 |
| structure and sequence analysis of yersinia yada and moraxella uspas reveal a novel class of adhesins. | the non-fimbrial adhesins, yada of enteropathogenic yersinia species, and uspa1 and uspa2 of moraxella catarrhalis, are established pathogenicity factors. in electron micrographs, both surface proteins appear as distinct 'lollipop'-shaped structures forming a novel type of surface projection on the outer membranes. these structures, amino acid sequence analysis of these molecules and yada gene manipulation suggest a tripartite organization: an n-terminal oval head domain is followed by a putativ ... | 2000 | 11080146 |
| improvement in bioreactor productivities using free radicals: hocl-induced overproduction of xanthan gum from xanthomonas campestris and its mechanism. | free-radical induction has been employed as a novel strategy to improve bioreactor productivity and, more specifically, the quality and productivity of xanthan gum from xanthomonas campestris cultures. a 210% increase in xanthan yield and a 20% increase in viscosity (quality) resulted from hocl (oxidant) treatment. the acetate mass fraction in xanthan gum decreased by 42% and its pyruvate mass fraction increased by 63% as a result of hocl treatment. the growth rate was almost unaffected by hocl ... | 2001 | 11084595 |
| a telomeric avirulence gene determines efficacy for the rice blast resistance gene pi-ta. | genetic mapping showed that the rice blast avirulence gene avr-pita is tightly linked to a telomere on chromosome 3 in the plant pathogenic fungus magnaporthe grisea. avr-pita corresponds in gene-for-gene fashion to the disease resistance (r) gene pi-ta. analysis of spontaneous avr-pita(-) mutants indicated that the gene is located in a telomeric 6.5-kb bglii restriction fragment. cloning and dna sequencing led to the identification of a candidate gene with features typical of metalloproteases. ... | 2000 | 11090206 |
| molecular evolution of virulence in natural field strains of xanthomonas campestris pv. vesicatoria. | the avrbs2 avirulence gene of the bacterial plant pathogen xanthomonas campestris pv. vesicatoria triggers disease resistance in pepper plants containing the bs2 resistance gene and contributes to bacterial virulence on susceptible host plants. we studied the effects of the pepper bs2 gene on the evolution of avrbs2 by characterizing the molecular basis for virulence of 20 x. campestris pv. vesicatoria field strains that were isolated from disease spots on previously resistant bs2 pepper plants. ... | 2000 | 11092868 |
| characterization of a major cluster of nif, fix, and associated genes in a sugarcane endophyte, acetobacter diazotrophicus. | a major 30.5-kb cluster of nif and associated genes of acetobacter diazotrophicus (syn. gluconacetobacter diazotrophicus), a nitrogen-fixing endophyte of sugarcane, was sequenced and analyzed. this cluster represents the largest assembly of contiguous nif-fix and associated genes so far characterized in any diazotrophic bacterial species. northern blots and promoter sequence analysis indicated that the genes are organized into eight transcriptional units. the overall arrangement of genes is most ... | 2000 | 11092875 |
| biological role of xanthomonadin pigments in xanthomonas campestris pv. campestris. | previous studies have indicated that the yellow pigments (xanthomonadins) produced by phytopathogenic xanthomonas bacteria are unimportant during pathogenesis but may be important for protection against photobiological damage. we used a xanthomonas campestris pv. campestris parent strain, single-site transposon insertion mutant strains, and chromosomally restored mutant strains to define the biological role of xanthomonadins. although xanthomonadin mutant strains were comparable to the parent st ... | 2000 | 11097878 |
| bacterial biodegradation of extractives and patterns of bordered pit membrane attack in pine wood. | wood extractives, commonly referred to as pitch, cause major problems in the manufacturing of pulp and paper. treatment of nonsterile southern yellow pine chips for 14 days with pseudomonas fluorescens, pseudomonas sp., xanthomonas campestris, and serratia marcescens reduced wood extractives by as much as 40%. control treatments receiving only water lost 11% of extractives due to the growth of naturally occurring microorganisms. control treatments were visually discolored after the 14-day incuba ... | 2000 | 11097890 |
| composition of soil microbial communities enriched on a mixture of aromatic hydrocarbons. | soil contaminated with c5+, which contained benzene (45%, wt/wt), dicyclopentadiene (dcpd) plus cyclopentadiene (together 20%), toluene (6%), styrene (3%), xylenes (2%), naphthalene (2%), and smaller quantities of other compounds, served as the source for isolation of 55 genomically distinct bacteria (standards). use of benzene as a substrate by these bacteria was most widespread (31 of 44 standards tested), followed by toluene (23 of 44), xylenes (14 of 44), styrene (10 of 44), and naphthalene ... | 2000 | 11097903 |
| functional tn5393-like transposon in the r plasmid pras2 from the fish pathogen aeromonas salmonicida subspecies salmonicida isolated in norway. | tn5393c containing stra-strb was identified as part of r plasmid pras2 from the fish pathogen aeromonas salmonicida subsp. salmonicida. this is the first time an intact and active transposon in the tn5393 family has been reported in an ecological niche other than an agricultural habitat. | 2000 | 11097945 |
| xv4-vrxv4: a new gene-for-gene interaction identified between xanthomonas campestris pv. vesicatoria race t3 and wild tomato relative lycopersicon pennellii. | strains of tomato race 3 (t3) of xanthomonas campestris pv. vesicatoria elicit a hypersensitive response (hr) in leaves of lycopersicon pennellii la716. genetic segregation of the resistance exhibited ratios near 3:1 in f2 populations, which confirmed that a single dominant gene controlled the inheritance of this trait. with the aid of a collection of introgression lines, restriction fragment length polymorphism, and cleaved amplified polymorphic sequence markers, the resistance locus was locate ... | 2000 | 11106027 |
| the chvh locus of agrobacterium encodes a homologue of an elongation factor involved in protein synthesis. | the virulence of agrobacterium tumefaciens depends on both chromosome- and ti plasmid-encoded gene products. in this study, we characterize a chromosomal locus, chvh, previously identified by tnphoa mutagenesis and shown to be required for tumor formation. through dna sequencing and comparison of the sequence with identified sequences in the database, we show that this locus encodes a protein similar in sequence to elongation factor p, a protein thought to be involved in peptide bond synthesis i ... | 2001 | 11114898 |
| hrpb2 and hrpf from xanthomonas are type iii-secreted proteins and essential for pathogenicity and recognition by the host plant. | the interaction between the plant pathogen xanthomonas campestris pv. vesicatoria and its host plants is controlled by hrp genes (hypersensitive reaction and pathogenicity), which encode a type iii protein secretion system. among type iii-secreted proteins are avirulence proteins, effectors involved in the induction of plant defence reactions. using non-polar mutants, we investigated the role of 12 hrp genes in the secretion of the avirulence protein avrbs3 from x. c. pv. vesicatoria and a heter ... | 2000 | 11115117 |
| xylella genomics and bacterial pathogenicity to plants. | xylella fastidiosa, a pathogen of citrus, is the first plant pathogenic bacterium for which the complete genome sequence has been published. inspection of the sequence reveals high relatedness to many genes of other pathogens, notably xanthomonas campestris. based on this, we suggest that xylella possesses certain easily testable properties that contribute to pathogenicity. we also present some general considerations for deriving information on pathogenicity from bacterial genomics. | 2000 | 11119303 |
| detection of bacterial virulence genes by subtractive hybridization: identification of capsular polysaccharide of burkholderia pseudomallei as a major virulence determinant. | burkholderia pseudomallei, the etiologic agent of melioidosis, is responsible for a broad spectrum of illnesses in humans and animals particularly in southeast asia and northern australia, where it is endemic. burkholderia thailandensis is a nonpathogenic environmental organism closely related to b. pseudomallei. subtractive hybridization was carried out between these two species to identify genes encoding virulence determinants in b. pseudomallei. screening of the subtraction library revealed a ... | 2001 | 11119486 |
| a two-component system involving an hd-gyp domain protein links cell-cell signalling to pathogenicity gene expression in xanthomonas campestris. | the synthesis of extracellular enzymes and extracellular polysaccharide (eps) in xanthomonas campestris pv. campestris (xcc) is regulated by a cluster of genes called rpf (for regulation of pathogenicity factors). two of the genes, rpff and rpfb, have previously been implicated in the synthesis of a diffusible regulatory molecule, dsf. here, we describe a screen of transposon insertion mutants of xcc that identified two dsf-overproducing strains. in each mutant, the gene disrupted is rpfc, which ... | 2000 | 11123673 |
| structure of the o-specific polysaccharides of the lipopolysaccharides of xanthomonas campestris pv. vignicola gspb 2795 and gspb 2796. | the o-specific polysaccharides of xanthomonas campestris pv. vignicola gspb 2795 and gspb 2796 were studied by sugar and methylation analyses, smith degradation, id, 2d 1h and 13c nmr spectroscopy. it was found that the polysaccharides are similar branched d-rhamnans lacking strict regularity, and their structures can be described as follows: [carbohydrate equation: see text] where rha(v) is present in a non-stoichiometric amount, which varies from strain to strain. | 2000 | 11125825 |
| relationship between glycolysis and exopolysaccharide biosynthesis in lactococcus lactis. | the relationships between glucose metabolism and exopolysaccharide (eps) production in a lactococcus lactis strain containing the eps gene cluster (eps(+)) and in nonproducer strain mg5267 (eps(-)) were characterized. the concentrations of relevant phosphorylated intermediates in eps and cell wall biosynthetic pathways or glycolysis were determined by (31)p nuclear magnetic resonance. the concentrations of two eps precursors, udp-glucose and udp-galactose, were significantly lower in the eps(+) ... | 2001 | 11133425 |
| direct cloning from enrichment cultures, a reliable strategy for isolation of complete operons and genes from microbial consortia. | enrichment cultures of microbial consortia enable the diverse metabolic and catabolic activities of these populations to be studied on a molecular level and to be explored as potential sources for biotechnology processes. we have used a combined approach of enrichment culture and direct cloning to construct cosmid libraries with large (>30-kb) inserts from microbial consortia. enrichment cultures were inoculated with samples from five environments, and high amounts of avidin were added to the cu ... | 2001 | 11133432 |
| pigment and virulence deficiencies associated with mutations in the aroe gene of xanthomonas oryzae pv. oryzae. | xanthomonadins are yellow, membrane-bound pigments produced by members of the genus xanthomonas. we identified an ethyl methanesulfonate-induced xanthomonas oryzae pv. oryzae mutant (bxo65) that is deficient for xanthomonadin production and virulence on rice, as well as auxotrophic for aromatic amino acids (pig(-) vir(-) aro(-)). reversion analysis indicated that these multiple phenotypes are due to a single mutation. a genomic library of the wild-type strain was used to isolate a 7.0-kb clone t ... | 2001 | 11133452 |
| pantoea agglomerans strain eh318 produces two antibiotics that inhibit erwinia amylovora in vitro. | pantoea agglomerans (synonym: erwinia herbicola) strain eh318 produces through antibiosis a complex zone of inhibited growth in an overlay seeded with erwinia amylovora, the causal agent of fire blight. this zone is caused by two antibiotics, named pantocin a and b. using a genomic library of eh318, two cosmids, pcpp702 and pcpp704, were identified that conferred on escherichia coli the ability to inhibit growth of e. amylovora. the two cosmids conferred different antibiotic activities on e. col ... | 2001 | 11133457 |
| involvement of the xpsn protein in formation of the xpsl-xpsm complex in xanthomonas campestris pv. campestris type ii secretion apparatus. | the xps gene cluster is required for the second step of type ii protein secretion in xanthomonas campestris pv. campestris. deletion of the entire gene cluster caused accumulation of secreted proteins in the periplasm. by analyzing protein abundance in the chromosomal mutant strains, we observed mutual dependence for normal steady-state levels between the xpsl and the xpsm proteins. the xpsl protein was undetectable in total lysate prepared from the xpsm mutant strain, and vice versa. introducti ... | 2001 | 11133946 |
| genetic and physiological characterization of ohr, encoding a protein involved in organic hydroperoxide resistance in pseudomonas aeruginosa. | the ohr (organic hydroperoxide resistance) gene product of pseudomonas aeruginosa was essential for optimal resistance to organic hydroperoxides (ohps) but not to hydrogen peroxide or paraquat. a deltaohr mutant was hypersusceptible to ohps in disk inhibition assays and showed enhanced killing by ohps in liquid culture. the ohr gene product was demonstrated to contribute to the decomposition of ohps. transcription of ohr was induced up to 15-fold upon exposure to ohps, and this induction was ind ... | 2001 | 11133975 |
| hxc2, an arabidopsis mutant with an altered hypersensitive response to xanthomonas campestris pv. campestris. | a chemical mutagenized population of arabidopsis col-0-gl plants was screened for an altered hypersensitive response (hr) after spray inoculation with an hr-inducing isolate of xanthomonas campestris pv. campestris (strain 147). three classes of mutant were identified: those exhibiting an hr- phenotype or partial loss of hr; hyper-responsive mutants showing necrotic lesions rapidly leading to the collapse of leaves; and susceptible mutants. one mutant belonging to the susceptible class, hxc-2, w ... | 2000 | 11135109 |
| comparison of antifungal activities and 16s ribosomal dna sequences of clinical and environmental isolates of stenotrophomonas maltophilia. | in recent years, the gram-negative bacterium stenotrophomonas maltophilia has become increasingly important in biotechnology and as a nosocomial pathogen, giving rise to a need for new information about its taxonomy and epidemiology. to determine intraspecies diversity and whether strains can be distinguished based on the sources of their isolation, 50 s. maltophilia isolates from clinical and environmental sources, including strains of biotechnological interest, were investigated. the isolates ... | 2001 | 11136762 |
| ion channel-forming alamethicin is a potent elicitor of volatile biosynthesis and tendril coiling. cross talk between jasmonate and salicylate signaling in lima bean. | alamethicin (ala), a voltage-gated, ion channel-forming peptide mixture from trichoderma viride, is a potent elicitor of the biosynthesis of volatile compounds in lima bean (phaseolus lunatus). unlike elicitation with jasmonic acid or herbivore damage, the blend of substances emitted comprises only the two homoterpenes, 4,11-dimethylnona-1,3,7-triene and 4,8,12-trimethyltrideca-1,3,7,11-tetraene, and methyl salicylate. inhibition of octadecanoid signaling by aristolochic acid and phenidone as we ... | 2001 | 11154344 |
| analysis of the type iv fimbrial-subunit gene fima of xanthomonas hyacinthi: application in pcr-mediated detection of yellow disease in hyacinths. | a sensitive and specific detection method was developed for xanthomonas hyacinthi; this method was based on amplification of a subsequence of the type iv fimbrial-subunit gene fima from strain s148. the fima gene was amplified by pcr with degenerate dna primers designed by using the n-terminal and c-terminal amino acid sequences of trypsin fragments of fima. the nucleotide sequence of fima was determined and compared with the nucleotide sequences coding for the fimbrial subunits in other type iv ... | 2001 | 11157222 |
| polysaccharide lyase: molecular cloning, sequencing, and overexpression of the xanthan lyase gene of bacillus sp. strain gl1. | when grown on xanthan as a carbon source, the bacterium bacillus sp. strain gl1 produces extracellular xanthan lyase (75 kda), catalyzing the first step of xanthan depolymerization (h. nankai, w. hashimoto, h. miki, s. kawai, and k. murata, appl. environ. microbiol. 65:2520-2526, 1999). a gene for the lyase was cloned, and its nucleotide sequence was determined. the gene contained an open reading frame consisting of 2,793 bp coding for a polypeptide with a molecular weight of 99,308. the polypep ... | 2001 | 11157235 |
| initiation of biofilm formation by pseudomonas aeruginosa 57rp correlates with emergence of hyperpiliated and highly adherent phenotypic variants deficient in swimming, swarming, and twitching motilities. | pseudomonas aeruginosa is a ubiquitous environmental bacterium capable of forming biofilms on surfaces as a survival strategy. it exhibits a large variety of competition/virulence factors, such as three types of motilities: flagellum-mediated swimming, flagellum-mediated swarming, and type iv pilus-mediated twitching. a strategy frequently used by bacteria to survive changing environmental conditions is to create a phenotypically heterogeneous population by a mechanism called phase variation. in ... | 2001 | 11157931 |
| identification and characterization of gsp65, an organic hydroperoxide resistance (ohr) gene encoding a general stress protein in enterococcus faecalis. | the enterococcus faecalis general stress protein gsp65 has been purified from two-dimensional gel electrophoresis. determination of its n-terminal sequence and characterization of the corresponding gene revealed that the gsp65 product is a 133-amino-acid protein sharing homologies with organic hydroperoxide resistance (ohr) proteins. transcriptional analysis of gsp65 gave evidence for a monocistronic mrna initiated 52 nucleotides upstream of the atg start codon and for an induction in response t ... | 2001 | 11157966 |
| catalase has a novel protective role against electrophile killing of xanthomonas. | the ability of xanthomonas: campestris pv. phaseoli to protect itself against lethal concentrations of man-made (n:-ethylmaleimide, nem) and endogenously produced (methylglyoxal, mg) electrophiles was investigated. pretreatment of x. c. pv. phaseoli with a low concentration of nem induced protection against lethal concentrations of nem and mg. mg pretreatment weakly induced protection against nem but not against mg itself. nem-induced protection against electrophile killing required new protein ... | 2001 | 11158366 |
| the insect endosymbiont sodalis glossinidius utilizes a type iii secretion system for cell invasion. | sodalis glossinidius is a maternally transmitted secondary endosymbiont residing intracellularly in tissues of the tsetse flies, glossina spp. in this study, we have used tn5 mutagenesis and a negative selection procedure to derive a s. glossinidius mutant that is incapable of invading insect cells in vitro and is aposymbiotic when microinjected into tsetse. this mutant strain harbors tn5 integrated into a chromosomal gene sharing high sequence identity with a type iii secretion system invasion ... | 2001 | 11172045 |
| from rags to riches: insights from the first genomic sequence of a plant pathogenic bacterium. | the recently published genomic sequence of xylella fastidiosa is the first for a free-living plant pathogen and provides clues to mechanisms of pathogenesis and survival in insect vectors. the sequence data should lead to improved control of this pathogen. | 2000 | 11178244 |
| molecular characterization and expression of the recx gene of xanthomonas campestris pv. citri. | two genes important in dna repair, reca and lexa, were recently identified in xanthomonas campestris pathovar citri (x.c. pv. citri). an open reading frame located immediately downstream of lexa and reca has now been isolated from this pathovar and characterized. this 486-bp open reading frame encodes a protein of 162 amino acids and shares substantial sequence similarity with recx of other bacterial species. the x.c. pv. citri recx protein was overexpressed in escherichia coli and purified; sds ... | 2001 | 11178726 |
| ethylene-dependent salicylic acid regulates an expanded cell death response to a plant pathogen. | the molecular events associated with susceptible plant responses to disease-causing organisms are not well understood. we have previously shown that ethylene-insensitive tomato plants infected with xanthomonas campestris pv. vesicatoria have greatly reduced disease symptoms relative to wild-type cultivars. here we show that salicylic acid (sa) is also an important component of the susceptible disease response. sa accumulates in infected wild-type tissues and is correlated with necrosis but does ... | 2001 | 11208023 |
| exchange of xcp (gsp) secretion machineries between pseudomonas aeruginosa and pseudomonas alcaligenes: species specificity unrelated to substrate recognition. | pseudomonas aeruginosa and pseudomonas alcaligenes are gram-negative bacteria that secrete proteins using the type ii or general secretory pathway, which requires at least 12 xcp gene products (xcpa and xcpp to -z). despite strong conservation of this secretion pathway, gram-negative bacteria usually cannot secrete exoproteins from other species. based on results obtained with erwinia, it has been proposed that the xcpp and/or xcpq homologs determine this secretion specificity (m. linderberg, g. ... | 2001 | 11208795 |
| the evolutionary history of chromosomal super-integrons provides an ancestry for multiresistant integrons. | integrons are genetic elements that acquire and exchange exogenous dna, known as gene cassettes, by a site-specific recombination mechanism. characterized gene cassettes consist of a target recombination sequence (attc site) usually associated with a single open reading frame coding for an antibiotic resistance determinant. the affiliation of multiresistant integrons (mris), which contain various combinations of antibiotic resistance gene cassettes, with transferable elements underlies the rapid ... | 2001 | 11209061 |
| structures of the o4 and o18 antigens of stenotrophomonas maltophilia: a case of enantiomeric repeating units. | the o-specific side-chain polymers of lipopolysaccharides from the reference strains for stenotrophomonas maltophilia serogroups 04 and o18 are both xylosylated rhamnans. in the 04 polymer, both sugar components are the d isomers, whereas the o18 polymer contains only the l isomers. by means of nmr spectroscopy, methylation analysis and smith degradation, the repeating unit of the 04 polymer was identified as a doubly-branched pentasaccharide of the structure shown below. the o18 polymer is base ... | 2001 | 11217974 |
| biological sensor for sucrose availability: relative sensitivities of various reporter genes. | a set of three sucrose-regulated transcriptional fusions was constructed. fusions p61rytir, p61rylac, and p61ryice contain the scrr sucrose repressor gene and the promoterless gfp, lacz, and inaz reporter genes, respectively, fused to the scry promoter from salmonella enterica serovar typhimurium. cells of erwinia herbicola containing these fusions are induced only in media amended with sucrose, fructose, or sorbose. while a large variation in sucrose-dependent reporter gene activity was observe ... | 2001 | 11229926 |
| salmonella host cell invasion emerged by acquisition of a mosaic of separate genetic elements, including salmonella pathogenicity island 1 (spi1), spi5, and sope2. | salmonella spp. possess a conserved type iii secretion system encoded within the pathogenicity island 1 (spi1; centisome 63), which mediates translocation of effector proteins into the host cell cytosol to trigger responses such as bacterial internalization. several translocated effector proteins are encoded in other regions of the salmonella chromosome. it remains unclear how this complex chromosomal arrangement of genes for the type iii apparatus and the effector proteins emerged and how the d ... | 2001 | 11244077 |
| complete dna sequence and comparative analysis of the 50-kilobase virulence plasmid of salmonella enterica serovar choleraesuis. | the complete nucleotide sequence of pkdsc50, a large virulence plasmid from salmonella enterica serovar choleraesuis strain rf-1, has been determined. we identified 48 of the open reading frames (orfs) encoded by the 49,503-bp molecule. pkdsc50 encodes a known virulence-associated operon, the spv operon, which is composed of genes essential for systemic infection by nontyphoidal salmonella. analysis of the genetic organization of pkdsc50 suggests that the plasmid is composed of several virulence ... | 2001 | 11254626 |
| an inner membrane platform in the type ii secretion machinery of gram-negative bacteria. | the type ii secretion machinery allows most gram-negative bacteria to deliver virulence factors into their surroundings. we report that in erwinia chrysanthemi, gspe (the putative ntpase), gspf, gspl and gspm constitute a complex in the inner membrane that is presumably used as a platform for assembling other parts of the secretion machinery. the gspe-gspf-gspl-gspm complex was demonstrated by two methods: (i) co-immunoprecipitation of gspe-gspf-gspl with antibodies raised against either gspe or ... | 2001 | 11266368 |
| hydrogen peroxide-forming nadh oxidase belonging to the peroxiredoxin oxidoreductase family: existence and physiological role in bacteria. | amphibacillus xylanus and sporolactobacillus inulinus nadh oxidases belonging to the peroxiredoxin oxidoreductase family show extremely high peroxide reductase activity for hydrogen peroxide and alkyl hydroperoxides in the presence of the small disulfide redox protein, ahpc (peroxiredoxin). in order to investigate the distribution of this enzyme system in bacteria, 15 bacterial strains were selected from typical aerobic, facultatively anaerobic, and anaerobic bacteria. ahpc-linked alkyl hydroper ... | 2001 | 11274101 |
| complete dna sequence and analysis of the large virulence plasmid of shigella flexneri. | the complete sequence analysis of the 210-kb shigella flexneri 5a virulence plasmid was determined. shigella spp. cause dysentery and diarrhea by invasion and spread through the colonic mucosa. most of the known shigella virulence determinants are encoded on a large plasmid that is unique to virulent strains of shigella and enteroinvasive escherichia coli; these known genes account for approximately 30 to 35% of the virulence plasmid. in the complete sequence of the virulence plasmid, 286 open r ... | 2001 | 11292750 |
| study of the role of antimicrobial glucosinolate-derived isothiocyanates in resistance of arabidopsis to microbial pathogens. | crude aqueous extracts from arabidopsis leaves were subjected to chromatographic separations, after which the different fractions were monitored for antimicrobial activity using the fungus neurospora crassa as a test organism. two major fractions were obtained that appeared to have the same abundance in leaves from untreated plants versus leaves from plants challenge inoculated with the fungus alternaria brassicicola. one of both major antimicrobial fractions was purified to homogeneity and iden ... | 2001 | 11299350 |
| evidence for the involvement of an oxidative stress in the initiation of infection of pear by erwinia amylovora. | involvement of an oxidative burst, usually related to incompatible plant/pathogen interactions leading to hypersensitive reactions, was investigated with erwinia amylovora, the causal agent of fire blight of maloideae subfamily of rosaceae, in interaction with pear (pyrus communis; compatible situation) and tobacco (nicotiana tabacum; incompatible situation). as expected, this necrogenic bacterium induced in tobacco a sustained production of superoxide anion, lipid peroxidation, electrolyte leak ... | 2001 | 11299395 |
| effects of urate, a natural inhibitor of peroxynitrite-mediated toxicity, in the response of arabidopsis thaliana to the bacterial pathogen pseudomonas syringae. | urate, a natural peroxynitrite scavenger, has been used to investigate the possible role of peroxynitrite during plant-pathogen interactions. urate greatly reduced lesion formation in arabidopsis leaves treated with an abiotic peroxynitrite-generating system or with a peroxynitrite solution, indicating that it can act as an effective scavenger in planta. in the interaction with the avirulent pseudomonas syringae pv. phaseolicola (avrrpm1+), cell death in the inoculated area was strongly reduced ... | 2001 | 11309143 |
| reduced expression of the tomato ethylene receptor gene leetr4 enhances the hypersensitive response to xanthomonas campestris pv. vesicatoria. | the hypersensitive response (hr) involves rapid death of cells at the site of pathogen infection and is thought to limit pathogen growth through the plant. ethylene regulates senescence and developmental programmed cell death, but its role in hypersensitive cell death is less clear. expression of two ethylene receptor genes, nr and leetr4, is induced in tomato (lycopersicon esculentum cv. mill) leaves during an hr to xanthomonas campestris pv. vesicatoria, with the greatest increase observed in ... | 2001 | 11310736 |
| stable transformation of the xylella fastidiosa citrus variegated chlorosis strain with oric plasmids. | xylella fastidiosa is a gram-negative, xylem-limited bacterium affecting economically important crops (e.g., grapevine, citrus, and coffee). the citrus variegated chlorosis (cvc) strain of x. fastidiosa is the causal agent of this severe disease of citrus in brazil and represents the first plant-pathogenic bacterium for which the genome sequence was determined. plasmids for the cvc strain of x. fastidiosa were constructed by combining the chromosomal replication origin (oric) of x. fastidiosa wi ... | 2001 | 11319110 |
| identification and characterization of a developmentally regulated protein, esha, required for sporogenic hyphal branches in streptomyces griseus. | to identify sporulation-specific proteins that might serve as targets of developmental regulatory factors in streptomyces, we examined total proteins of streptomyces griseus by two-dimensional gel electrophoresis. among five proteins that were present at high levels during sporulation but absent from vegetative cells, two of the proteins, p3 and p4, were absent from developmental mutants that undergo aberrant morphogenesis. the deduced amino acid sequence of the gene that encodes p3 (esha) showe ... | 2001 | 11325927 |
| roles of aconitase in growth, metabolism, and morphological differentiation of streptomyces coelicolor. | the studies of aconitase presented here, along with those of citrate synthase (p. h. viollier, w. minas, g. e. dale, m. folcher, and c. j. thompson, j. bacteriol. 183:3184-3192, 2001), were undertaken to investigate the role of the tricarboxylic acid (tca) cycle in streptomyces coelicolor development. a single aconitase activity (acoa) was detected in protein extracts of cultures during column purification. the deduced amino acid sequence of the cloned acoa gene constituted the n-terminal sequen ... | 2001 | 11325949 |
| xanthomonas campestris strain selection for xanthan production from olive mill wastewaters. | four xanthomonas campestris strains were tested in olive mill wastewaters (omw) for xanthan production. differences among strains were found in the range of tolerance to omw concentration and xanthan amount obtained. x. campestris nrrl b-1459 s4lii was chosen by its capability for xanthan production from 50-60% omw as the sole nutrient source. | 2001 | 11329685 |
| genetic mapping and functional analysis of the tomato bs4 locus governing recognition of the xanthomonas campestris pv. vesicatoria avrbs4 protein. | xanthomonas campestris pv. vesicatoria is the causal agent of bacterial spot disease on pepper (capsicum spp.) and tomato (lycopersicon spp.). analysis of 17 different lycopersicon accessions with avrbs4-expressing x. campestris pv. vesicatoria strains identified 15 resistant and two susceptible tomato genotypes. genetic analysis revealed that avrbs4 recognition in tomato is governed by a single locus, designated bs4 (bacterial spot resistance locus no. 4). amplified fragment length polymorphism ... | 2001 | 11332727 |
| characterization and mutational analysis of three allelic lsc genes encoding levansucrase in pseudomonas syringae. | in the plant pathogen pseudomonas syringae pv. glycinea pg4180 and other bacterial species, synthesis of the exopolysaccharide levan is catalyzed by the extracellular enzyme levansucrase. the results of southern blotting and pcr analysis indicated the presence of three levansucrase-encoding genes in strain pg4180: lsca, lscb, and lscc. in this study, lscb and lscc were cloned from a genomic library of strain pg4180. sequence analysis of the two lsc genes showed that they were virtually identical ... | 2001 | 11344135 |
| the effect of olive mill wastewaters variability on xanthan production. | xanthan production by xanthomonas campestris from several olive mill wastewaters (omw) was investigated. | 2001 | 11348445 |
| the early stages of filamentous phage philf infection require the host transcription factor, clp. | xanthomonas campestris pv. campestris produces great amounts of an exopolysaccharide (eps), xanthan gum. eight eps loci involved in biosynthesis of the eps were previously located in the chromosome map of strain xc17. in this study, the eps8 region was cloned, sequenced and found to contain a crp homologue whose deduced amino acid sequence possesses similarity to that of the cyclic amp receptor protein of bacteria, with the highest identity (97%) being shared with the x. campestris pv. campestri ... | 2001 | 11361081 |
| structural and functional characterization of the lexa gene of xanthomonas campestris pathovar citri. | the role of the lexa protein and, specifically, its effect on reca expression were analyzed in xanthomonas campestris pathovar citri (x.c. pv. citri). overexpression of lexa from x.c. pv. citri, in the plant pathogen, as well as in escherichia coli, results in increased sensitivity to the dna-damaging agents mitomycin c and ultraviolet radiation, indicating that the recombinant x.c. pv. citri lexa protein is functional in a different bacterial species. immunoblot analysis revealed that the overe ... | 2001 | 11361343 |