| cdc group iv c-2: a new ralstonia species close to ralstonia eutropha. | cdc group iv c-2, an environmental gram-negative bacillus recently proposed for inclusion in the genus ralstonia, has been isolated in several human infections. biochemical characterization and 16s ribosomal dna (rdna) sequencing with phylogenetic analysis were used to characterize eight clinical isolates and four type strains. other typing tools, such as pulsed-field gel electrophoresis (pfge) and randomly amplified polymorphic dna (rapd) analysis, were also used. pfge typing of clinical isolat ... | 1999 | 10325323 |
| phylogenetic analysis of ara+ and ara- burkholderia pseudomallei isolates and development of a multiplex pcr procedure for rapid discrimination between the two biotypes. | a burkholderia pseudomallei-like organism has recently been identified among some soil isolates of b. pseudomallei in an area with endemic melioidosis. this organism is almost identical to b. pseudomallei in terms of morphological and biochemical profiles, except that it differs in ability to assimilate l-arabinose. these ara+ isolates are also less virulent than the ara- isolates in animal models. in addition, clinical isolates of b. pseudomallei available to date are almost exclusively ara-. t ... | 1999 | 10325345 |
| glyceraldehyde-3-phosphate dehydrogenase gene diversity in eubacteria and eukaryotes: evidence for intra- and inter-kingdom gene transfer. | cyanobacteria contain up to three highly divergent glyceraldehyde-3-phosphate dehydrogenase (gapdh) genes: gap1, gap2, and gap3. genes gap1 and gap2 are closely related at the sequence level to the nuclear genes encoding cytosolic and chloroplast gapdh of higher plants and have recently been shown to play distinct key roles in catabolic and anabolic carbon flow, respectively, of the unicellular cyanobacterium synechocystis sp. pcc6803. in the present study, sequences of 10 gapdh genes distribute ... | 1999 | 10331270 |
| saccharomyces cerevisiae cells harboring the gene encoding sarcotoxin ia secrete a peptide that is toxic to plant pathogenic bacteria. | sarcotoxin ia is a cecropin-type antibacterial protein produced by the flesh fly, sarcophaga peregrina. similar to other bactericidal small proteins produced by insects, sarcotoxin ia is released into the hemolymph of larvae and nymphs upon mechanical injury or bacterial infection. the gene (sarco) that encodes this toxin was introduced into saccharomyces cerevisiae yeast cells and was expressed under a constitutive yeast promoter. the transformed yeast cells were grown in a liquid medium, and a ... | 1999 | 10336869 |
| molecular characterization of a brucella species large dna fragment deleted in brucella abortus strains: evidence for a locus involved in the synthesis of a polysaccharide. | a brucella melitensis 16m dna fragment of 17,119 bp, which contains a large region deleted in b. abortus strains and dna flanking one side of the deletion, has been characterized. in addition to the previously identified omp31 gene, 14 hypothetical genes have been identified in the b. melitensis fragment, most of them showing homology to genes involved in the synthesis of a polysaccharide. considering that 10 of the 15 genes are missing in b. abortus and that all the polysaccharides described in ... | 1999 | 10338472 |
| quantitative immunofluorescence of regulated eps gene expression in single cells of ralstonia solanacearum. | ralstonia solanacearum, a phytopathogenic bacterium, uses an environmentally sensitive and complex regulatory network to control expression of multiple virulence genes. part of this network is an unusual autoregulatory system that produces and senses 3-hydroxypalmitic acid methyl ester. in culture, this autoregulatory system ensures that expression of virulence genes, such as those of the eps operon encoding biosynthesis of the acidic extracellular polysaccharide, occurs only at high cell densit ... | 1999 | 10347013 |
| cells of escherichia coli contain a protein-tyrosine kinase, wzc, and a phosphotyrosine-protein phosphatase, wzb. | two proteins of escherichia coli, termed wzc and wzb, were analyzed for their capacity to participate in the reversible phosphorylation of proteins on tyrosine. first, wzc was overproduced from its specific gene and purified to homogeneity by affinity chromatography. upon incubation in the presence of radioactive atp, it was found to effectively autophosphorylate. two-dimensional analysis of its phosphoamino acid content revealed that it was modified exclusively at tyrosine. second, wzb was also ... | 1999 | 10348860 |
| antimicrobial properties of alkamides present in flavouring plants traditionally used in mesoamerica: affinin and capsaicin. | the bioactive amides affinin and capsaicin isolated respectively from heliopsis longipes roots and capsicum spp fruits, were assayed for activity against escherichia coli, pseudomonas solanacearum, bacillus subtilis and saccharomyces cerevisicae suspension cultures. the alkamide affinin inhibited growth of e. coli and s. cerevisiae at concentrations as low as 25 microg/ml. higher concentrations of affinin were necessary to inhibit growth of p. solanacearum and b. subtilis. however. high concentr ... | 1999 | 10363839 |
| identification of burkholderia spp. in the clinical microbiology laboratory: comparison of conventional and molecular methods. | cystic fibrosis (cf) predisposes patients to bacterial colonization and infection of the lower airways. several species belonging to the genus burkholderia are potential cf-related pathogens, but microbiological identification may be complicated. this situation is not in the least due to the poorly defined taxonomic status of these bacteria, and further validation of the available diagnostic assays is required. a total of 114 geographically diverse bacterial isolates, previously identified in re ... | 1999 | 10364579 |
| differentiation of burkholderia species by pcr-restriction fragment length polymorphism analysis of the 16s rrna gene and application to cystic fibrosis isolates. | burkholderia cepacia, which is an important pathogen in cystic fibrosis (cf) owing to the potential severity of the infections and the high transmissibility of some clones, has been recently shown to be a complex of five genomic groups, i.e., genomovars i, ii (b. multivorans), iii, and iv and b. vietnamiensis. b. gladioli is also involved, though rarely, in cf. since standard laboratory procedures fail to provide an accurate identification of these organisms, we assessed the ability of restricti ... | 1999 | 10364586 |
| the mdoc gene of escherichia coli encodes a membrane protein that is required for succinylation of osmoregulated periplasmic glucans. | osmoregulated periplasmic glucans (opgs) of escherichia coli are anionic oligosaccharides that accumulate in the periplasmic space in response to low osmolarity of the medium. their anionic character is provided by the substitution of the glucosidic backbone by phosphoglycerol originating from the membrane phospholipids and by succinyl residues from unknown origin. a phosphoglycerol-transferase-deficient mdob mutant was subjected to tn5 transposon mutagenesis, and putative mutant clones were scr ... | 1999 | 10368134 |
| analysis of a capsular polysaccharide biosynthesis locus of bacteroides fragilis. | a major clinical manifestation of infection with bacteroides fragilis is the formation of intra-abdominal abscesses, which are induced by the capsular polysaccharides of this organism. transposon mutagenesis was used to locate genes involved in the synthesis of capsular polysaccharides. a 24,454-bp region was sequenced and found to contain a 15,379-bp locus (designated wcf) with 16 open reading frames (orfs) encoding products similar to those encoded by genes of other bacterial polysaccharide bi ... | 1999 | 10377135 |
| characterization of an arabidopsis thaliana receptor-like protein kinase gene activated by oxidative stress and pathogen attack. | an arabidopsis thaliana cdna clone that encodes a putative receptor-like protein kinase gene (at-rlk3) was characterized. the deduced 667-amino acid protein consists of an amino-terminal signal sequence, an extracellular domain, a single transmembrane domain, and a cytoplasmic domain with characteristics of serine/threonine protein kinase. because of the original features of its extracellular domain, the at-rlk3 protein is a member of a new class of receptor-like protein kinases. the at-rlk3 gen ... | 1999 | 10377997 |
| swarming by pseudomonas syringae b728a requires gacs (lema) and gaca but not the acyl-homoserine lactone biosynthetic gene ahli. | pseudomonas syringae pv. syringae b728a, a causal agent of bacterial brown spot on snap beans, swarms with a characteristic dendritic pattern on semisolid (0.4%) agar plates. filamentation of swarming cells of b728a was not observed. mutations in either the gacs (formerly lema) or gaca gene of b728a eliminate the ability of this p. syringae isolate to swarm without obvious effects on bacterial motility. three field isolates showed a similar dependence on gacs for swarming. since gacs and gaca mu ... | 1999 | 10383988 |
| quantification of chemotaxis to naphthalene by pseudomonas putida g7. | the capillary assay was used to quantify the chemotactic response of pseudomonas putida g7 to naphthalene. experiments were conducted in which the cell concentration in the assay chamber, the naphthalene concentration in the capillary, or the incubation time was varied. data from these experiments were evaluated with a model that accounted for the effect of diffusion on the distribution of substrate and the transport of cells from the chamber through the capillary orifice. by fitting a numerical ... | 1999 | 10388674 |
| amplified rdna restriction analysis and further genotypic characterisation of metal-resistant soil bacteria and related facultative hydrogenotrophs. | the level of genotypic relationship between czc+ soil bacteria mainly resistant to zinc (but also to various other metals), and related facultative hydrogenotrophs previously assigned to the genera alcaligenes, ralstonia, and burkholderia was evaluated using ardra (amplified ribosomal dna restriction analysis). the analysis included 44 strains isolated from harsh industrial environments in sediments, soils and wastes with high content of heavy metals. these strains were selected by their ability ... | 1999 | 10390877 |
| a simple extraction procedure for efficient routine detection of pathogenic bacteria in plant material by polymerase chain reaction. | a simple and rapid method for extracting dna from plants based on the use of an extraction buffer and precipitation with isopropanol was assayed to see its usefulness in detecting pathogenic bacteria in plant material. the method was compared with a phenol-chloroform standard procedure obtaining higher sensitivity levels of detection. the protocol developed was efficient for detecting a gram-positive bacterium, clavibacter michiganensis subsp. sepedonicus and several gram-negative pathogenic bac ... | 1999 | 10395461 |
| evidence for the presence in burkholderia pseudomallei of a type iii secretion system-associated gene cluster. | burkholderia pseudomallei, the causative agent of melioidosis, contains a cluster of putative genes homologous to those encoding hpap, hrcq, hrcr, hrcs and hrpv in the plant pathogen ralstonia solanacearum. in r. solanacearum, these genes form part of a type iii secretion-associated pathogenicity island. the order of the genes in b. pseudomallei is directly equivalent to that found in r. solanacearum. the b. pseudomallei proteins share 49.5% (hpap), 52.6% (hrcq), 80.0% (hrcr), 72.1% (hrcs) and 4 ... | 1999 | 10403415 |
| cloning, molecular analysis, and expression of the polyhydroxyalkanoic acid synthase (phac) gene from chromobacterium violaceum. | the polyhydroxyalkanoic acid synthase gene from chromobacterium violaceum (phac(cv)) was cloned and characterized. a 6.3-kb bamhi fragment was found to contain both phac(cv) and the polyhydroxyalkanoic acid (pha)-specific 3-ketothiolase (phaa(cv)). escherichia coli strains harboring this fragment produced significant levels of pha synthase and 3-ketothiolase, as judged by their activities. while c. violaceum accumulated poly(3-hydroxybutyrate) or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) when ... | 1999 | 10427049 |
| the xanthomonas hrp type iii system secretes proteins from plant and mammalian bacterial pathogens. | studies of essential pathogenicity determinants in gram-negative bacteria have revealed the conservation of type iii protein secretion systems that allow delivery of virulence factors into host cells from plant and animal pathogens. ten of 21 hrp proteins of the plant pathogen xanthomonas campestris pv. vesicatoria have been suggested to be part of a type iii machinery. here, we report the hrp-dependent secretion of two avirulence proteins, avrbs3 and avrrxv, by x. campestris pv. vesicatoria str ... | 1999 | 10430949 |
| staphylococcus aureus cap5p encodes a udp-n-acetylglucosamine 2-epimerase with functional redundancy. | the serotype 5 capsule gene cluster of staphylococcus aureus comprises 16 genes (cap5a through cap5p), but little is known about how the putative gene products function in capsule biosynthesis. we propose that the n-acetylmannosaminuronic acid (mannaca) component of the s. aureus serotype 5 capsular polysaccharide (cp5) is synthesized from a udp-n-acetylglucosamine (udp-glcnac) precursor that is epimerized to udp-n-acetylmannosamine (udp-mannac) and then oxidized to udp-mannaca. we report the pu ... | 1999 | 10438750 |
| genetic and biochemical characterization of an exopolygalacturonase and a pectate lyase from yersinia enterocolitica. | yersinia enterocolitica, an invasive foodborne human pathogen, degrades polypectate by producing two depolymerizing enzymes, pectate lyase (pl) and polygalacturonase (pg). the gene encoding the pg activity, designated pehy, was located in a 3-kb genomic fragment of y. enterocolitica atcc 49397. the complete nucleotide sequence of this 3-kb fragment was determined and an open reading frame consisting of 1803 bp was predicted to encode a pg protein with an estimated m(r) of 66 kda and pi of 6.3. t ... | 1999 | 10446714 |
| the 17-gene ethanolamine (eut) operon of salmonella typhimurium encodes five homologues of carboxysome shell proteins. | the eut operon of salmonella typhimurium encodes proteins involved in the cobalamin-dependent degradation of ethanolamine. previous genetic analysis revealed six eut genes that are needed for aerobic use of ethanolamine; one (eutr), encodes a positive regulator which mediates induction of the operon by vitamin b12 plus ethanolamine. the dna sequence of the eut operon included 17 genes, suggesting a more complex pathway than that revealed genetically. we have correlated an open reading frame in t ... | 1999 | 10464203 |
| identification and characterization of cdna clones encoding hydroxycinnamoyl-coa:tyramine n-hydroxycinnamoyltransferase from tobacco. | the sequences of three cdna clones that include the complete coding region of hydroxycinnamoyl-coa:tyramine n-hydroxycinnamoyltransferase (tht) from tobacco are reported. the three cdnas were isolated by antibody screening of a cdna expression library produced from poly(a)+rna purified from tobacco leaves (nicotiana tabacum cv. bottom special), previously infiltrated with an incompatible strain of ralstonia solanacearum. the identity of these clones was confirmed by the detection of tht activity ... | 1999 | 10469131 |
| comparison of bacterial community structures in the rhizoplane of tomato plants grown in soils suppressive and conducive towards bacterial wilt. | it has been reported that the growth of ralstonia solanacearum is suppressed at the rhizoplane of tomato plants and that tomato bacterial wilt is suppressed in plants grown in a soil (mutsumi) in japan. to evaluate the biological factors contributing to the suppressiveness of the soil in three treated mutsumi soils (chloroform fumigated soil; autoclaved soil mixed with intact mutsumi soil; and autoclaved soil mixed with intact, wilt-conducive yamadai soil) infested with r. solanacearum, we bioas ... | 1999 | 10473407 |
| genetics of o-antigen biosynthesis in pseudomonas aeruginosa. | pathogenic bacteria produce an elaborate assortment of extracellular and cell-associated bacterial products that enable colonization and establishment of infection within a host. lipopolysaccharide (lps) molecules are cell surface factors that are typically known for their protective role against serum-mediated lysis and their endotoxic properties. the most heterogeneous portion of lps is the o antigen or o polysaccharide, and it is this region which confers serum resistance to the organism. pse ... | 1999 | 10477307 |
| an hrcu-homologous gene mutant of xanthomonas campestris pv. glycines 8ra that lost pathogenicity on the host plant but was able to elicit the hypersensitive response on nonhosts. | transposon mutagenesis was used to isolate nonpathogenic mutants of xanthomonas campestris pv. glycines 8ra, which causes bacterial pustule disease in soybean. a 6.1-kb dna region in which a mutation gave loss of pathogenicity was isolated and found to carry six open reading frames (orfs). four orfs had homology with hrcu, hrcv, hrcr, and hrcs genes of ralstonia solanacearum and x. campestris pv. vesicatoria. one nonpathogenic mutant, x. campestris pv. glycines h80, lost pathogenicity on soybean ... | 1999 | 10478481 |
| involvement of the cis/trans isomerase cti in solvent resistance of pseudomonas putida dot-t1e. | pseudomonas putida dot-t1e is a solvent-resistant strain that is able to grow in the presence of high concentrations of toluene. we have cloned and sequenced the cti gene of this strain, which encodes the cis/trans isomerase, termed cti, that catalyzes the cis-trans isomerization of esterified fatty acids in phospholipids, mainly cis-oleic acid (c(16:1,9)) and cis-vaccenic acid (c(18:1,11)), in response to solvents. to determine the importance of this cis/trans isomerase for solvent resistance a ... | 1999 | 10482510 |
| identification of a pathogenicity island, which contains genes for virulence and avirulence, on a large native plasmid in the bean pathogen pseudomonas syringae pathovar phaseolicola. | the 154-kb plasmid was cured from race 7 strain 1449b of the phytopathogen pseudomonas syringae pv. phaseolicola (pph). cured strains lost virulence toward bean, causing the hypersensitive reaction in previously susceptible cultivars. restoration of virulence was achieved by complementation with cosmid clones spanning a 30-kb region of the plasmid that contained previously identified avirulence (avr) genes avrd, avrpphc, and avrpphf. single transposon insertions at multiple sites (including one ... | 1999 | 10485919 |
| quinolone signaling in the cell-to-cell communication system of pseudomonas aeruginosa. | numerous species of bacteria use an elegant regulatory mechanism known as quorum sensing to control the expression of specific genes in a cell-density dependent manner. in gram-negative bacteria, quorum sensing systems function through a cell-to-cell signal molecule (autoinducer) that consists of a homoserine lactone with a fatty acid side chain. such is the case in the opportunistic human pathogen pseudomonas aeruginosa, which contains two quorum sensing systems (las and rhl) that operate via t ... | 1999 | 10500159 |
| identification of regions of the chromosome of neisseria meningitidis and neisseria gonorrhoeae which are specific to the pathogenic neisseria species. | neisseria meningitidis and neisseria gonorrhoeae give rise to dramatically different diseases. their interactions with the host, however, do share common characteristics: they are both human pathogens which do not survive in the environment and which colonize and invade mucosa at their port of entry. it is therefore likely that they have common properties that might not be found in nonpathogenic bacteria belonging to the same genetically related group, such as neisseria lactamica. their common p ... | 1999 | 10531275 |
| immunochemical characterization and taxonomic evaluation of the o polysaccharides of the lipopolysaccharides of pseudomonas syringae serogroup o1 strains. | the o polysaccharide (ops) of the lipopolysaccharide (lps) of pseudomonas syringae pv. atrofaciens imv 7836 and some other strains that are classified in serogroup o1 was shown to be a novel linear alpha-d-rhamnan with the tetrasaccharide o repeat -->3)-alpha-d-rhap-(1-->3)-alpha-d-rhap-(1-->2)-alpha-d-r hap-(1-->2)- alpha-d-rhap-(1--> (chemotype 1a). the same alpha-d-rhamnan serves as the backbone in branched opss with lateral (alpha1-->3)-linked d-rhap, (beta1-->4)-linked d-glcpnac, and (alpha ... | 1999 | 10559159 |
| steps in the development of a vibrio cholerae el tor biofilm. | we report that, in a simple, static culture system, wild-type vibrio cholerae el tor forms a three-dimensional biofilm with characteristic water channels and pillars of bacteria. furthermore, we have isolated and characterized transposon insertion mutants of v. cholerae that are defective in biofilm development. the transposons were localized to genes involved in (i) the biosynthesis and secretion of the mannose-sensitive haemagglutinin type iv pilus (msha); (ii) the synthesis of exopolysacchari ... | 1999 | 10564499 |
| fluobodies: green fluorescent single-chain fv fusion proteins. | an expression system (pskgfp), which permits the expression of single-chain variable fragments as fusion proteins with modified green fluorescent proteins, was designed. this expression system is comparable to frequently used phage display vectors and allows single-step characterization of the selected recombinant antibodies by flow cytometry or fluorescent cell staining. two different single-chain variable fragment antibodies, both directed against the lipopolysaccharide of the bacterium ralsto ... | 1999 | 10594359 |
| species-specific pcr as a tool for the identification of burkholderia gladioli. | burkholderia gladioli colonizes the respiratory tracts of patients with cystic fibrosis and chronic granulomatous disease. however, due to the high degree of phenotypic similarity between this species and closely related species in the burkholderia cepacia complex, accurate identification is difficult. incorrect identification of these species may have serious repercussions for the management of patients with cystic fibrosis. to develop an accurate procedure for the identification of b. gladioli ... | 2000 | 10618102 |
| hbpr, a new member of the xylr/dmpr subclass within the ntrc family of bacterial transcriptional activators, regulates expression of 2-hydroxybiphenyl metabolism in pseudomonas azelaica hbp1. | the regulation of 2-hydroxybiphenyl and 2,2'-dihydroxybiphenyl degradation in pseudomonas azelaica is mediated by the regulatory gene, hbpr. the hbpr gene encodes a 63-kda protein belonging to the ntrc family of prokaryotic transcriptional activators and having the highest homology to members of the xylr/dmpr subclass. disruption of the hbpr gene in p. azelaica and complementation in trans showed that the hbpr protein was the key regulator for 2-hydroxybiphenyl metabolism. induction experiments ... | 2000 | 10629187 |
| ralstonia eutropha tf93 is blocked in tat-mediated protein export. | ralstonia eutropha (formerly alcaligenes eutrophus) tf93 is pleiotropically affected in the translocation of redox enzymes synthesized with an n-terminal signal peptide bearing a twin arginine (s/t-r-r-x-f-l-k) motif. immunoblot analyses showed that the catalytic subunits of the membrane-bound [nife] hydrogenase (mbh) and the molybdenum cofactor-binding periplasmic nitrate reductase (nap) are mislocalized to the cytoplasm and to the inner membrane, respectively. moreover, physiological studies s ... | 2000 | 10633089 |
| application of 16s rrna gene sequencing to identify bordetella hinzii as the causative agent of fatal septicemia. | we report on the first case of fatal septicemia caused by bordetella hinzii. the causative organism exhibited a biochemical profile identical to that of bordetella avium with three commercial identification systems (api 20e, api 20 ne, and vitek gni+ card). however, its cellular fatty acid profile was not typical for either b. avium or previously reported strains of b. hinzii. presumptive identification of the patient's isolate was accomplished by traditional biochemical testing, and definitive ... | 2000 | 10655386 |
| presence of type iii secretion genes in burkholderia pseudomallei correlates with ara(-) phenotypes. | dot blot hybridization and pcr amplification of 14 ara(+) and 8 ara(-) burkholderia pseudomallei strains showed that type iii secretion (tts) genes were present in all the ara(-) strains but absent from all but one of the ara(+) strains. the link between tts genes and an ara(-) phenotype suggests a role for tts in virulence. | 2000 | 10655407 |
| resistance of tomato line hawaii7996 to ralstonia solanacearum pss4 in taiwan is controlled mainly by a major strain-specific locus. | bacterial wilt caused by the soilborne bacterium ralstonia solanacearum attacks hundreds of plant species, including many agriculturally important crops. natural resistance to this disease has been found in some species and is usually inherited as a polygenic trait. in tomato, a model crop plant, genetic analysis previously revealed the involvement of several qtl (quantitative trait loci) controlling resistance and, in all of these studies with different strains of the pathogen, loci on chromoso ... | 2000 | 10656580 |
| the gene coding for the hrp pilus structural protein is required for type iii secretion of hrp and avr proteins in pseudomonas syringae pv. tomato. | bacterial surface appendages called pili often are associated with dna and/or protein transfer between cells. the exact function of pili in the transfer process is not understood and is a matter of considerable debate. the hrp pilus is assembled by the hrp type iii protein secretion system of pseudomonas syringae pv. tomato (pst) strain dc3000. in this study, we show that the hrpa gene, which encodes the major subunit of the hrp pilus, is required for secretion of putative virulence proteins, su ... | 2000 | 10681465 |
| the hrpb and hrpg regulatory genes of ralstonia solanacearum are required for different stages of the tomato root infection process. | hrp genes, encoding type iii secretion machinery, have been shown to be key determinants for pathogenicity in the vascular phytopathogenic bacterium ralstonia solanacearum gmi1000. here, we show phenotypes of r. solanacearum mutant strains disrupted in the prhj, hrpg, or hrpb regulatory genes with respect to root infection and vascular colonization in tomato plants. tests of bacterial colonization and enumeration in tomato plants, together with microscopic observations of tomato root sections, r ... | 2000 | 10707351 |
| identification of two novel hrp-associated genes in the hrp gene cluster of xanthomonas oryzae pv. oryzae. | we have cloned a hrp gene cluster from xanthomonas oryzae pv. oryzae. bacteria with mutations in the hrp region have reduced growth in rice leaves and lose the ability to elicit a hypersensitive response (hr) on the appropriate resistant cultivars of rice and the nonhost plant tomato. a 12,165-bp portion of nucleotide sequence from the presumed left end and extending through the hrpb operon was determined. the region was most similar to hrp genes from xanthomonas campestris pv. vesicatoria and r ... | 2000 | 10714988 |
| aiia, an enzyme that inactivates the acylhomoserine lactone quorum-sensing signal and attenuates the virulence of erwinia carotovora. | n-acylhomoserine lactones, known as autoinducers (ais), are widely conserved signal molecules present in quorum-sensing systems of many gram-negative bacteria. ais are involved in the regulation of diverse biological functions, including expression of pathogenic genes in the plant pathogens pseudomonas solanacearum, several erwinia species, and the human pathogen pseudomonas aeruginosa. a bacterial isolate, bacillus sp. 240b1, is capable of enzymatic inactivation of ais. the gene (aiia) for ai i ... | 2000 | 10716724 |
| the phytopathogenic bacteria erwinia carotovora infects drosophila and activates an immune response. | although drosophila possesses potent immune responses, little is known about the microbial pathogens that infect drosophila. we have identified members of the bacterial genus erwinia that induce the systemic expression of genes encoding antimicrobial peptides in drosophila larvae after ingestion. these erwinia strains are phytopathogens and use flies as vectors; our data suggest that these strains have also evolved mechanisms for exploiting their insect vectors as hosts. erwinia infections induc ... | 2000 | 10725405 |
| detection of type iii secretion system genes in animal isolates of bordetella bronchiseptica. | a cosmid clone bank of bordetella bronchiseptica genomic dna was screened for the presence of type iii secretion (tts) genes using a probe derived from the tts system genes of ralstonia solanacearum. a 3.35kb psti fragment, sub-cloned from a hybridising cosmid clone, was sequenced and found to contain a 97bp overlap with the previously reported b. bronchiseptica bscijklno tts gene cluster. dna and predicted protein homology analysis suggests that a bscpqrst cluster lies immediately downstream of ... | 2000 | 10727842 |
| genetic diversity and biological control activity of novel species of closely related pseudomonads isolated from wheat field soils in south australia. | rhizobacteria closely related to two recently described species of pseudomonads, pseudomonas brassicacearum and pseudomonas thivervalensis, were isolated from two geographically distinct wheat field soils in south australia. isolation was undertaken by either selective plating or immunotrapping utilizing a polyclonal antibody raised against p. brassicacearum. a subset of 42 isolates were characterized by amplified 16s ribosomal dna restriction analysis (ardra), biolog analysis, and gas chromatog ... | 2000 | 10742249 |
| [the effect of the substance exin on development of microbial infections and isolation of ethylene in plants]. | effects of exin on infection of tomato, potato, and cabbage plants with pseudomonas solanacearum and erwinia carotovora and a fungus sclerotium rolfsii were studied. the treatment of infected plants with exin caused no significant effect on the development of the disease. treatment with streptomycin as a standard for comparison completely inhibited the growth of these microorganisms. pretreatment with exin one to eight days before infecting inhibited the development of diseases. the numbers of t ... | 2000 | 10780015 |
| the pseudomonas syringae hrp pathogenicity island has a tripartite mosaic structure composed of a cluster of type iii secretion genes bounded by exchangeable effector and conserved effector loci that contribute to parasitic fitness and pathogenicity in plants. | the plant pathogenic bacterium pseudomonas syringae is divided into pathovars differing in host specificity, with p. syringae pv. syringae (psy) and p. syringae pv. tomato (pto) representing particularly divergent pathovars. p. syringae hrp/hrc genes encode a type iii protein secretion system that appears to translocate avr and hop effector proteins into plant cells. dna sequence analysis of the hrp/hrc regions in psy 61, psy b728a, and pto dc3000 has revealed a hrp pathogenicity island (pai) wi ... | 2000 | 10781092 |
| luxr- and acyl-homoserine-lactone-controlled non-lux genes define a quorum-sensing regulon in vibrio fischeri. | the luminescence (lux) operon (luxicdabeg) of the symbiotic bacterium vibrio fischeri is regulated by the transcriptional activator luxr and two acyl-homoserine lactone (acyl-hsl) autoinducers (the luxi-dependent 3-oxo-hexanoyl-hsl [3-oxo-c6-hsl] and the ains-dependent octanoyl-hsl [c8-hsl]) in a population density-responsive manner called quorum sensing. to identify quorum-sensing-regulated (qsr) proteins different from those encoded by lux genes, we examined the protein patterns of v. fischeri ... | 2000 | 10781550 |
| development of a highly sensitive nested-pcr procedure using a single closed tube for detection of erwinia amylovora in asymptomatic plant material. | a novel method, which involves a nested pcr in a single closed tube, was developed for the sensitive detection of erwinia amylovora in plant material. the external and internal primer pairs used had different annealing temperatures and directed the amplification of a specific dna fragment from plasmid pea29. the procedure involved two consecutive pcrs, the first of which was performed at a higher annealing temperature that allowed amplification only by the external primer pair. using pure cultur ... | 2000 | 10788384 |
| distinguishing species of the burkholderia cepacia complex and burkholderia gladioli by automated ribotyping. | several species belonging to the genus burkholderia are clinically relevant, opportunistic pathogens that inhabit major environmental reservoirs. consequently, the availability of means for adequate identification and epidemiological characterization of individual environmental or clinical isolates is mandatory. in the present communication we describe the use of the riboprinter microbial characterization system (qualicon, warwick, united kingdom) for automated ribotyping of 104 strains of burkh ... | 2000 | 10790116 |
| ralstonia solanacearum produces hrp-dependent pili that are required for popa secretion but not for attachment of bacteria to plant cells. | as in many other gram-negative plant pathogenic bacteria, the ralstonia solanacearum hrp genes are involved in the production of a type iii secretion apparatus that allows the translocation of popa protein to the external medium. here, we show that hrp genes are also involved in the biogenesis of pili that are mainly composed of the hrpy protein. these pili are produced at one pole of the bacterium and are also released into the external medium where they can form very long straight bundles. an ... | 2000 | 10792714 |
| two novel proteins, popb, which has functional nuclear localization signals, and popc, which has a large leucine-rich repeat domain, are secreted through the hrp-secretion apparatus of ralstonia solanacearum. | the ralstonia solanacearum hrp gene cluster codes for components of a type iii secretion pathway necessary for the secretion of popa1, a hypersensitive response-like elicitor protein. in the present study, we show that several other hrp-secreted proteins can be detected by growing wild-type bacteria in minimal medium in the presence of congo red. two of these proteins, popb and popc, are encoded by genes located downstream of popa and constitute an operon with popa. popabc mutants retain the wil ... | 2000 | 10792715 |
| serological and molecular size characterization of flagellins of pseudomonas syringae pathovars and related bacteria | flagella from a total of 118 strains representing mostly pathovars of the phytopathogenic group pseudomonas syringae, but also p. chlororaphis, p. cichorii, p. corrugata, p. fluorescens, p. fuscovaginae, p. stutzeri, p. viridiflava, as well as related phytopathogenic genera (burkholderia cepacia and ralstonia solanacearum) were characterized by immuno-fluorescent staining, sds-page, and immunoblotting. eighty-six strains of the p. syringae group pathovars, p. cichorii and p. viridiflava were sho ... | 1999 | 10794141 |
| a bacterial sensor of plant cell contact controls the transcriptional induction of ralstonia solanacearum pathogenicity genes. | the hrp genes of the plant pathogen ralstonia solanacearum are key pathogenicity determinants; they encode a type iii protein secretion machinery involved in the secretion of mediators of the bacterium-plant interaction. these hrp genes are under the genetic control of the hrpb regulatory gene, expression of which is induced when bacteria are co-cultivated with plant cell suspensions. in this study, we used hrp-gfp transcriptional fusions to demonstrate that the expression of the hrpb and type i ... | 2000 | 10811621 |
| evidence for a signaling system in helicobacter pylori: detection of a luxs-encoded autoinducer. | helicobacter pylori possesses a homolog of the luxs gene, initially identified by its role in autoinducer production for the quorum-sensing system 2 in vibrio harveyi. the genomes of several other species of bacteria, notably escherichia coli, salmonella enterica serovar typhimurium, and vibrio cholerae, also include luxs homologs. all of these bacteria have been shown to produce active autoinducers capable of stimulating the expression of the luciferase operon in v. harveyi. in this report, we ... | 2000 | 10850976 |
| virulence of the phytopathogen pseudomonas syringae pv. maculicola is rpon dependent. | we cloned the rpon (ntra and glnf) gene encoding sigma(54) from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. the p. syringae es4326 rpon gene complemented pseudomonas aeruginosa, escherichia coli, and klebsiella aerogenes rpon mutants for a variety of rpon mutant phenotypes, including the inability to utilize nitrate as sole nitrogen source. dna sequence analysis of the p. syringae es4326 rpon gene revealed that the deduced amino acid sequence was most similar (86% identi ... | 2000 | 10852883 |
| the alternative sigma factor rpon is required for hrp activity in pseudomonas syringae pv. maculicola and acts at the level of hrpl transcription. | beta-glucuronidase (uida) reporter gene fusions were constructed for the hrpz, hrpl, and hrps genes from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. these reporters, as well as an avrrpt2-uida fusion, were used to measure transcriptional activity in es4326 and a es4326 rpon mutant. rpon was required for the expression of avrrpt2, hrpz, and hrpl in vitro in minimal media and in vivo when infiltrated into arabidopsis thaliana leaves. in contrast, the expression of hrps was ... | 2000 | 10852884 |
| effect of model sorptive phases on phenanthrene biodegradation: molecular analysis of enrichments and isolates suggests selection based on bioavailability. | reduced bioavailability of nonpolar contaminants due to sorption to natural organic matter is an important factor controlling biodegradation of pollutants in the environment. we established enrichment cultures in which solid organic phases were used to reduce phenanthrene bioavailability to different degrees (r. j. grosser, m. friedrich, d. m. ward, and w. p. inskeep, appl. environ. microbiol. 66:2695-2702, 2000). bacteria enriched and isolated from contaminated soils under these conditions were ... | 2000 | 10877758 |
| detection of ralstonia solanacearum strains with a quantitative, multiplex, real-time, fluorogenic pcr (taqman) assay. | a fluorogenic (taqman) pcr assay was developed to detect ralstonia solanacearum strains. two fluorogenic probes were utilized in a multiplex reaction; one broad-range probe (rs) detected all biovars of r. solanacearum, and a second more specific probe (b2) detected only biovar 2a. amplification of the target was measured by the 5' nuclease activity of taq dna polymerase on each probe, resulting in emission of fluorescence. taqman pcr was performed with dna extracted from 42 r. solanacearum and g ... | 2000 | 10877778 |
| genetic diversity of ralstonia solanacearum as assessed by pcr-rflp of the hrp gene region, aflp and 16s rrna sequence analysis, and identification of an african subdivision. | the genetic diversity among strains in a worldwide collection of ralstonia solanacearum, causal agent of bacterial wilt, was assessed by using three different molecular methods. pcr-rflp analysis of the hrp gene region was extended from previous studies to include additional strains and showed that five amplicons were produced not only with all r. solanacearum strains but also with strains of the closely related bacteria pseudomonas syzygii and the blood disease bacterium (bdb). however, the thr ... | 2000 | 10878132 |
| 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 |
| 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 |
| a framework for interpreting the leucine-rich repeats of the listeria internalins. | the surface protein inlb of the bacterial pathogen listeria monocytogenes is required for inducing phagocytosis in various nonphagocytic mammalian cell types in vitro. inlb causes tyrosine phosphorylation of host cell adaptor proteins, activation of phosphoinositide 3-kinase, and rearrangements of the actin cytoskeleton. these events lead to phagocytic uptake of the bacterium by the host cell. inlb belongs to the internalin family of listeria proteins, which also includes inla, another surface p ... | 2000 | 10922035 |
| 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 |
| response of a soil bacterial community to grassland succession as monitored by 16s rrna levels of the predominant ribotypes. | the composition of predominant soil bacteria during grassland succession was investigated in the dutch drentse a area. five meadows, taken out of agricultural production at different time points, and one currently fertilized plot represented different stages of grassland succession. since fertilization and agricultural production were stopped, the six plots showed a constant decline in the levels of nutrients and vegetation changes. the activity of the predominant bacteria was monitored by direc ... | 2000 | 10966420 |
| toluene-degrading bacteria are chemotactic towards the environmental pollutants benzene, toluene, and trichloroethylene. | the bioremediation of polluted groundwater and toxic waste sites requires that bacteria come into close physical contact with pollutants. this can be accomplished by chemotaxis. five motile strains of bacteria that use five different pathways to degrade toluene were tested for their ability to detect and swim towards this pollutant. three of the five strains (pseudomonas putida f1, ralstonia pickettii pko1, and burkholderia cepacia g4) were attracted to toluene. in each case, the response was de ... | 2000 | 10966434 |
| identification and characteristics of a novel burkholderia strain with broad-spectrum antimicrobial activity. | a burkholderia strain isolated from soil is capable of inhibiting the growth of bacteria, plant-pathogenic fungi, pathogenic yeasts, and protozoa. inhibition does not involve cell contact or the presence of living cells, suggesting that at least a substantial portion of the antimicrobial activity is due to the excretion of extracellular compounds. | 2000 | 10966443 |
| plant genome complexity may be a factor limiting in situ the transfer of transgenic plant genes to the phytopathogen ralstonia solanacearum. | the development of natural competence by bacteria in situ is considered one of the main factors limiting transformation-mediated gene exchanges in the environment. ralstonia solanacearum is a plant pathogen that is also a naturally transformable bacterium that can develop the competence state during infection of its host. we have attempted to determine whether this bacterium could become the recipient of plant genes. we initially demonstrated that plant dna was released close to the infecting ba ... | 2000 | 10966449 |
| orit-directed cloning of defined large regions from bacterial genomes: identification of the sinorhizobium meliloti pexo megaplasmid replicator region. | we have developed a procedure to directly clone large fragments from the genome of the soil bacterium sinorhizobium meliloti. specific regions to be cloned are first flanked by parallel copies of an origin of transfer (orit) together with a plasmid replication origin capable of replicating large clones in escherichia coli but not in the target organism. supplying transfer genes in trans specifically transfers the orit-flanked region, and in this process, site-specific recombination at the orit s ... | 2000 | 10986253 |
| synergistic hydrolysis of carboxymethyl cellulose and acid-swollen cellulose by two endoglucanases (celz and cely) from erwinia chrysanthemi. | erwinia chrysanthemi produces a battery of hydrolases and lyases which are very effective in the maceration of plant cell walls. although two endoglucanases (celz and cely; formerly egz and egy) are produced, celz represents approximately 95% of the total carboxymethyl cellulase activity. in this study, we have examined the effectiveness of cely and celz alone and of combinations of both enzymes using carboxymethyl cellulose (cmc) and amorphous cellulose (acid-swollen cellulose) as substrates. s ... | 2000 | 11004164 |
| 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 |
| a bioluminescent whole-cell reporter for detection of 2, 4-dichlorophenoxyacetic acid and 2,4-dichlorophenol in soil. | a bioreporter was made containing a tfdrp(dii)-luxcdabe fusion in a modified mini-tn5 construct. when it was introduced into the chromosome of ralstonia eutropha jmp134, the resulting strain, jmp134-32, produced a sensitive bioluminescent response to 2, 4-dichlorophenoxyacetic acid (2,4-d) at concentrations of 2.0 microm to 5.0 mm. this response was linear (r(2) = 0.9825) in the range of 2.0 microm to 1.1 x 10(2) microm. saturation occurred at higher concentrations, with maximal bioluminescence ... | 2000 | 11010925 |
| regulation of hrp genes and type iii protein secretion in erwinia amylovora by hrpx/hrpy, a novel two-component system, and hrps. | two novel regulatory components, hrpx and hrpy, of the hrp system of erwinia amylovora were identified. the hrpxy operon is expressed in rich media, but its transcription is increased threefold by low ph, nutrient, and temperature levels--conditions that mimic the plant apoplast. hrpxy is autoregulated and directs the expression of hrpl; hrpl, in turn, activates transcription of other loci in the hrp gene cluster (z.-m. wei and s. v. beer, j. bacteriol. 177:6201-6210, 1995). the deduced amino -a ... | 2000 | 11059492 |
| evidence that ralstonia eutropha (alcaligenes eutrophus) contains a functional homologue of the ralstonia solanacearum phc cell density sensing system. | in the phytopathogen ralstonia (pseudomonas) solanacearum, control of many virulence genes is partly mediated by the phc cell density sensing system. phc uses a novel self-produced signal molecule [3-hydroxypalmitic acid methyl ester (3-oh pame)], an atypical two-component system (phcs/phcr), and a lysr-type activator (phca) to regulate a reversible switching between two different physiological states. while phc is present in most r. solanacearum strains, it is apparently absent from other pseud ... | 2000 | 11069661 |
| multicomponent transcriptional regulation at the complex promoter of the exopolysaccharide i biosynthetic operon of ralstonia solanacearum. | high-level transcription of eps, an operon encoding biosynthesis of an exopolysaccharide virulence factor of the phytopathogen ralstonia (pseudomonas) solanacearum, requires the products of at least seven regulatory genes (phca, phcb, xpsr, vsra-vsrd, and vsrb-vsrc), which are organized in three converging signal transduction cascades. because xpsr and the vsrb-vsrc two-component system are the most downstream cascade components required for activation of eps, we explored how these components co ... | 2000 | 11073909 |
| 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 |
| sequence diversity of rula among natural isolates of pseudomonas syringae and effect on function of rulab-mediated uv radiation tolerance. | the rulab locus confers tolerance to uv radiation and is borne on plasmids of the ppt23a family in pseudomonas syringae. we sequenced 14 rula alleles from p. syringae strains representing seven pathovars and found sequence differences of 1 to 12% within pathovar syringae, and up to 15% differences between pathovars. since the sequence variation within rula was similar to that of p. syringae chromosomal alleles, we hypothesized that rulab has evolved over a long time period in p. syringae. a phyl ... | 2000 | 11097885 |
| sequencing bands of ribosomal intergenic spacer analysis fingerprints for characterization and microscale distribution of soil bacterium populations responding to mercury spiking. | two major emerging bands (a 350-bp band and a 650-bp band) within the risa (ribosomal intergenic spacer analysis) profile of a soil bacterial community spiked with hg(ii) were selected for further identification of the populations involved in the response of the community to the added metal. the bands were cut out from polyacrylamide gels, cloned, characterized by restriction analysis, and sequenced for phylogenetic affiliation of dominant clones. the sequences were the intergenic spacer between ... | 2000 | 11097911 |
| identification and detection of stenotrophomonas maltophilia by rrna-directed pcr. | stenotrophomonas maltophilia has recently emerged as an important nosocomial pathogen in immunocompromised patients, in transplant recipients, and in persons with cystic fibrosis (cf). while this organism is nonpathogenic in healthy individuals, it is increasingly associated with morbidity and mortality in susceptible populations. recent studies have indicated that for approximately 10% of cf patients with moderate lung disease, s. maltophilia can be cultured from respiratory tract secretions. i ... | 2000 | 11101555 |
| coupling of flagellar gene expression to flagellar assembly in salmonella enterica serovar typhimurium and escherichia coli. | how do organisms assess the degree of completion of a large structure, especially an extracellular structure such as a flagellum? bacteria can do this. mutants that lack key components needed early in assembly fail to express proteins that would normally be added at later assembly stages. in some cases, the regulatory circuitry is able to sense completion of structures beyond the cell surface, such as completion of the external hook structure. in salmonella and escherichia coli, regulation occur ... | 2000 | 11104815 |
| pathogenesis of the human opportunistic pathogen pseudomonas aeruginosa pa14 in arabidopsis. | the human opportunistic pathogen pseudomonas aeruginosa strain pa14 is a multihost pathogen that can infect arabidopsis. we found that pa14 pathogenesis in arabidopsis involves the following steps: attachment to the leaf surface, congregation of bacteria at and invasion through stomata or wounds, colonization of intercellular spaces, and concomitant disruption of plant cell wall and membrane structures, basipetal movement along the vascular parenchyma, and maceration and rotting of the petiole a ... | 2000 | 11115892 |
| ralstonia solanacearum--a plant pathogen in touch with its host. | | 2000 | 11121751 |
| novel tellurite-amended media and specific chromosomal and ti plasmid probes for direct analysis of soil populations of agrobacterium biovars 1 and 2. | ecology and biodiversity studies of agrobacterium spp. require tools such as selective media and dna probes. tellurite was tested as a selective agent and a supplement of previously described media for agrobacteria. the known biodiversity within the genus was taken into account when the selectivity of k(2)teo(3) was analyzed and its potential for isolating agrobacterium spp. directly from soil was evaluated. a k(2)teo(3) concentration of 60 ppm was found to favor the growth of agrobacteria and r ... | 2001 | 11133429 |
| two-component system that regulates methanol and formaldehyde oxidation in paracoccus denitrificans. | a chromosomal region encoding a two-component regulatory system, flhrs, has been isolated from paracoccus denitrificans. flhrs-deficient mutants were unable to grow on methanol, methylamine, or choline as the carbon and energy source. expression of the gene encoding glutathione-dependent formaldehyde dehydrogenase (fhla) was undetectable in the mutant, and expression of the s-formylglutathione hydrolase gene (fgha) was reduced in the mutant background. in addition, methanol dehydrogenase was imm ... | 2001 | 11133961 |
| hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro. | the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ... | 2001 | 11134504 |
| hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro. | the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ... | 2001 | 11134504 |
| variation in the spacer regions separating trna genes in renibacterium salmoninarum distinguishes recent clinical isolates from the same location. | a means for distinguishing between clinical isolates of renibacterium salmoninarum that is based on the pcr amplification of length polymorphisms in the trna intergenic spacer regions (tdna-ilps) was investigated. the method used primers specific to nucleotide sequences of r. salmoninarum trna genes and trna intergenic spacer regions that had been generated by using consensus trna gene primers. twenty-one pcr products were sequenced from five isolates of r. salmoninarum from the united states, e ... | 2001 | 11136759 |
| ralstonia paucula (formerly cdc group iv c-2): unsuccessful strain differentiation with pcr-based methods, study of the 16s-23s spacer of the rrna operon, and comparison with other ralstonia species (r. eutropha, r. pickettii, r. gilardii, and r. solanacearum). | ralstonia paucula (formerly cdc group iv c-2) can cause serious human infections. confronted in 1995 with five cases of nosocomial bacteremia, we found that pulsed-field gel electrophoresis could not distinguish between the isolates and that randomly amplified polymorphic dna analysis was poorly discriminatory. in this study, we used pcr-ribotyping and pcr-restriction fragment length polymorphism analysis of the spacer 16s-23s ribosomal dna (rdna); both methods were unable to differentiate r. pa ... | 2001 | 11136807 |
| nickel-resistance-based minitransposons: new tools for genetic manipulation of environmental bacteria. | the ncc and nre nickel resistance determinants from ralstonia eutropha-like strain 31a were used to construct mini-tn5 transposons. broad host expression of nickel resistance was observed for the nre minitransposons in members of the alpha, beta, and gamma subclasses of the proteobacteria, while the ncc minitransposons expressed nickel resistance only in r. eutropha-like strains. | 2001 | 11157282 |
| 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 |
| vpsr, a member of the response regulators of the two-component regulatory systems, is required for expression of vps biosynthesis genes and eps(etr)-associated phenotypes in vibrio cholerae o1 el tor. | the rugose colonial variant of vibrio cholerae o1 el tor produces an exopolysaccharide (eps(etr)) that enables the organism to form a biofilm and to resist oxidative stress and the bactericidal action of chlorine. transposon mutagenesis of the rugose variant led to the identification of vpsr, which codes for a homologue of the ntrc subclass of response regulators. targeted disruption of vpsr in the rugose colony genetic background yielded a nonreverting smooth-colony morphotype that produced no ... | 2001 | 11160103 |
| resistance to bacterial wilt in somatic hybrids between solanum tuberosum and solanum phureja. | somatic hybrid plants were produced after protoplast electrofusion between a dihaploid potato, cv. bf15, and a wild tuber-bearing relative, solanum phureja, with a view to transferring bacterial wilt resistance into potato lines. a total of ten putative hybrids were selected. dna analysis using flow cytometry revealed that six were tetraploids, two mixoploids, one amphiploid and one octoploid. in the greenhouse, the putative hybrids exhibited strong vigor and were morphologically intermediate, i ... | 2000 | 11164589 |
| source of resistance against ralstonia solanacearum in fertile somatic hybrids of eggplant (solanum melongena l.) with solanum aethiopicum l. | solanum aethiopicum is reported to carry resistance to bacterial wilt disease caused by ralstonia solanacearum, which is one of the most important diseases of eggplant (solanum melongena). these two species can sexually be crossed but the fertility of their progeny is very low. in order to transfer the resistance and improve the fertility, somatic hybrids between s. melongena cv. dourga and two groups of s. aethiopicum were produced by electrical fusion of mesophyll protoplasts. thirty hybrid pl ... | 2001 | 11164602 |
| 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 |
| genetic snapshots of the rhizobium species ngr234 genome. | in nitrate-poor soils, many leguminous plants form nitrogen-fixing symbioses with members of the bacterial family rhizobiaceae. we selected rhizobium sp. ngr234 for its exceptionally broad host range, which includes more than i 12 genera of legumes. unlike the genome of bradyrhizobium japonicum, which is composed of a single 8.7 mb chromosome, that of ngr234 is partitioned into three replicons: a chromosome of about 3.5 mb, a megaplasmid of more than 2 mb (pngr234b) and pngr234a, a 536,165 bp pl ... | 2000 | 11178268 |
| qscr, a modulator of quorum-sensing signal synthesis and virulence in pseudomonas aeruginosa. | the opportunistic pathogenic bacterium pseudomonas aeruginosa uses quorum-sensing signaling systems as global regulators of virulence genes. there are two quorum-sensing signal receptor and signal generator pairs, lasr-lasi and rhlr-rhli. the recently completed p. aeruginosa genome-sequencing project revealed a gene coding for a homolog of the signal receptors, lasr and rhlr. here we describe a role for this gene, which we call qscr. the qscr gene product governs the timing of quorum-sensing-con ... | 2001 | 11226312 |
| genetic evidence that loss of virulence associated with gacs or gaca mutations in pseudomonas syringae b728a does not result from effects on alginate production. | mutations in the global regulatory genes gacs and gaca render pseudomonas syringae pv. syringae strain b728a completely nonpathogenic in foliar infiltration assays on bean plants. it had been previously demonstrated that gac genes regulate alginate production in pseudomonas species, while other published work indicated that alginate is involved in the pathogenic interaction of p. syringae on bean plants. together, these results suggested that the effects of gacs and gaca mutations on virulence i ... | 2001 | 11229941 |