Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| 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 |
| generation of pcr-based dna fragments for specific detection of streptomyces saraceticus n45. | streptomyces saraceticus strain n45, a saprophytic gram-positive bacteria, has been shown to harbor high chitinase activity. due to its potential use in biological control, the cloning of chitinase genes and the development of methods to quickly and precisely detect its presence have become necessary. in this study, pcr-based random amplified polymorphic dna (rapd) and pcr strategies were used to amplify random dna fragments from the genome of s. saraceticus n45. three amplified dna fragments, 4 ... | 2001 | 11370759 |
| the luxm homologue vanm from vibrio anguillarum directs the synthesis of n-(3-hydroxyhexanoyl)homoserine lactone and n-hexanoylhomoserine lactone. | vibrio anguillarum, which causes terminal hemorrhagic septicemia in fish, was previously shown to possess a luxri-type quorum-sensing system (vanri) and to produce n-(3-oxodecanoyl)homoserine lactone (3-oxo-c10-hsl). however, a vani null mutant still activated n-acylhomoserine lactone (ahl) biosensors, indicating the presence of an additional quorum-sensing circuit in v. anguillarum. in this study, we have characterized this second system. using high-pressure liquid chromatography in conjunction ... | 2001 | 11371516 |
| requirement for phosphoglucomutase in exopolysaccharide biosynthesis in glucose- and lactose-utilizing streptococcus thermophilus. | to study the influence of phosphoglucomutase (pgm) activity on exopolysaccharide (eps) synthesis in glucose- and lactose-growing streptococcus thermophilus, a knockout pgm mutant and a strain with elevated pgm activity were constructed. the pgma gene, encoding pgm in s. thermophilus ly03, was identified and cloned. the gene was functional in escherichia coli and was shown to be expressed from its own promoter. the pgma-deficient mutant was unable to grow on glucose, while the mutation did not af ... | 2001 | 11375188 |
| quantitative pcr method for diagnosis of citrus bacterial canker. | for diagnosis of citrus bacterial canker by pcr, an internal standard is employed to ensure the quality of the dna extraction and that proper requisites exist for the amplification reaction. the ratio of pcr products from the internal standard and bacterial target is used to estimate the initial bacterial concentration in citrus tissues with lesions. | 2001 | 11375206 |
| [role of the surface and extracellular substances of the phytopathogenic bacterium xanthomonas campestris in its interactions with cabbage plants]. | changes in some physiological and biochemical characteristics of cabbage (cv. slava) seedling roots in response to inoculation with the phytopathogen xanthomonas campestris and its surface and extracellular substances were evaluated. seven days after the inoculation, the growth of the roots was slightly suppressed and they contained increased amounts of peroxidase. the effect of the lipopolysaccharides stripped from the cell surface or isolated from the culture liquid of x. campestris was simila ... | 2001 | 11386062 |
| expression of the gum operon directing xanthan biosynthesis in xanthomonas campestris and its regulation in planta. | the gum gene cluster of xanthomonas campestris pv. campestris comprises 12 genes whose products are involved in the biosynthesis of the extracellular polysaccharide xanthan. these genes are expressed primarily as an operon from a promoter upstream of the first gene, gumb. although the regulation of xanthan synthesis in vitro has been well studied, nothing is known of its regulation in planta. a reporter plasmid was constructed in which the promoter region of the gum operon was fused to gusa. in ... | 2001 | 11386372 |
| induction of hydroxycinnamoyl-tyramine conjugates in pepper by xanthomonas campestris, a plant defense response activated by hrp gene-dependent and hrp gene-independent mechanisms. | inoculation of pepper leaves, capsicum annuum cv. early calwonder ecw 10r, with strains of xanthomonas campestris led to an accumulation of the phenolic conjugates feruloyltyramine (ft) and p-coumaroyltyramine (ct) 24 h postinoculation in nonhost- and gene-for-gene-determined incompatible interactions with x. campestris pv. campestris and x. campestris pv. vesicatoria, respectively. in contrast, neither compound was detected in compatible interactions with x. campestris pv. vesicatoria. the accu ... | 2001 | 11386374 |
| microbial origin of plant-type 2-keto-3-deoxy-d-arabino-heptulosonate 7-phosphate synthases, exemplified by the chorismate- and tryptophan-regulated enzyme from xanthomonas campestris. | enzymes performing the initial reaction of aromatic amino acid biosynthesis, 2-keto-3-deoxy-d-arabino-heptulosonate 7-phosphate (dahp) synthases, exist as two distinct homology classes. the three classic escherichia coli paralogs are aroa(i) proteins, but many members of the bacteria possess the aroa(ii) class of enzyme, sometimes in combination with aroa(i) proteins. aroa(ii) dahp synthases until now have been shown to be specifically dedicated to secondary metabolism (e.g., formation of ansamy ... | 2001 | 11395471 |
| kinetic analysis of growth and xanthan gum production with xanthomonas campestris on sucrose, using sequentially consumed nitrogen sources. | a batch fermentation strategy using xanthomonas campestris atcc 13951 for xanthan gum production has been established in which all essential medium components are supplied at the onset. this has been achieved using sucrose as sole sugar feedstock. sequential consumption of nitrogen sources (soybean hydrolysates, ammonium and nitrate salts) was observed to facilitate the further optimisation of the medium. biomass accumulation was limited by phosphate availability. xanthan yields of more than 60% ... | 2001 | 11398920 |
| complete dna sequence of yersinia enterocolitica serotype 0:8 low-calcium-response plasmid reveals a new virulence plasmid-associated replicon. | the complete nucleotide sequence and organization of the yersinia enterocolitica serotype 0:8 low-calcium-response (lcr) plasmid, pyve8081, were determined. the 67,720-bp plasmid encoded all the genes known to be part of the lcr stimulon except for ylpa. eight of 13 intact open reading frames of unknown function identified in pyve8081 had homologues in yersinia pestis plasmid pcd1 or in y. enterocolitica serotype 0:9 plasmid pyve227. a region of approximately 17 kbp showed no dna identity to pcd ... | 2001 | 11402007 |
| characterization and expression of beta-1,3-glucanase genes in peach. | beta-1,3-glucanase is one of the pathogenesis-related (pr) proteins involved in plant defense responses. a peach beta-1,3-glucanase gene, designated ppgns1, has been isolated and characterized. the deduced amino acid sequence of the product of ppgns indicates that it is a basic isoform (pi 9.8), and contains a putative signal peptide of 38 amino acids but has no c-terminal extension. amino acid sequence comparisons revealed that ppgns1 is 69% and 67% identical to citrus and soybean beta-1,3-gluc ... | 2001 | 11405630 |
| broad-spectrum antimicrobial activity in vitro of the synthetic peptide d4e1. | broad-spectrum antimicrobial activity of a synthetic peptide, d4e1, is documented in this paper. d4e1 inhibited the growth of several fungal phytopathogens belonging to four classes-ascomycetes, basidiomycetes, deuteromycetes, and oomycetes, and two bacterial pathogens, pseudomonas syringae pv. tabaci and xanthomonas campestris pv. malvacearum race 18. the minimum inhibitory concentration (mic) of d4e1 required to completely inhibit the growth of all fungi studied ranged from 4.67 to 25 microm. ... | 2001 | 11409968 |
| incipient erosion of biostabilized sediments examined using particle-field optical holography. | laser holography allows images of three-dimensional space at ultra-high resolution to be recorded onto photographic plates. recorded scenes can be "replayed" with a second laser beam into free space and optically "interrogated" using either a microscope or a camera by sequentially focusing on increasing distances from the hologram in the field of view (optical sectioning). from these sections, information on the relative locations and orientation in space of suspended particles as well as the mo ... | 2001 | 11414032 |
| ohrr is a repressor of ohra, a key organic hydroperoxide resistance determinant in bacillus subtilis. | bacillus subtilis displays a complex adaptive response to the presence of reactive oxygen species. to date, most proteins that protect against reactive oxygen species are members of the peroxide-inducible perr and sigma(b) regulons. we investigated the function of two b. subtilis homologs of the xanthomonas campestris organic hydroperoxide resistance (ohr) gene. mutational analyses indicate that both ohra and ohrb contribute to organic peroxide resistance in b. subtilis, with the ohra protein pl ... | 2001 | 11418552 |
| influence of acidic exopolysaccharide of xanthomonas campestris ibpm 124 on the kinetic parameters of extracellular bacteriolytic enzymes. | interactions of a negatively charged exopolysaccharide of xanthomonas campestris ibpm 124 with its extracellular enzymes (muramidase, endopeptidase, and neutral phosphatase) and also with egg lysozyme, lysostaphin, muramidase of streptomyces globisporus, and a bacteriolytic enzyme complex of streptomyces albus were studied. all these enzymes were positively charged under the conditions of their maximal activity. it was shown that interaction of the acidic exopolysaccharide from x. campestris wit ... | 2001 | 11421816 |
| bacterial ohr and osmc paralogues define two protein families with distinct functions and patterns of expression. | xanthomonas campestris ohr (a protein involved in organic peroxide protection) and escherichia coli osmc (an osmotically inducible protein of unknown function) are related proteins. database searches and phylogenetic analyses reveal that ohr and osmc homologues cluster into two related subfamilies of proteins widely distributed in both gram-negative and gram-positive bacteria. to determine if these two subfamilies are functionally distinct, ohr and osmc in pseudomonas aeruginosa (a bacterium wit ... | 2001 | 11429455 |
| two cinnamoyl-coa reductase (ccr) genes from arabidopsis thaliana are differentially expressed during development and in response to infection with pathogenic bacteria. | cinnamoyl-coa reductase (ccr; ec 1.2.1.44) catalyses the conversion of cinnamoyl-coas into their corresponding cinnamaldehydes, i.e. the first step of the phenylpropanoid pathway specifically dedicated to the monolignol biosynthetic branch. in previous work, we described the isolation and characterisation of the first cdna encoding ccr in eucalyptus (lacombe, e., hawkins, s., van dorsselaere, j., piquemal, j., goffner, d., poeydomenge, o., boudet, a.m., grima-pettenati, j., 1997. cinnamoyl coa r ... | 2001 | 11430991 |
| eukaryotic features of the xanthomonas type iii effector avrbs3: protein domains involved in transcriptional activation and the interaction with nuclear import receptors from pepper. | the avrbs3 protein of the phytopathogenic bacterium xanthomonas campestris pv. vesicatoria is targeted to host-plant cells by the bacterial hrp type iii secretion system. in pepper plants containing the bs3 resistance gene, avrbs3 induces the hypersensitive response (hr). avrbs3 recognition is thought to occur in the plant cell nucleus as hr induction is dependent on nuclear localization signals (nlss) and an acidic transcription activation domain (aad). in a search for avrbs3-interacting pepper ... | 2001 | 11439138 |
| complex regulation of the organic hydroperoxide resistance gene (ohr) from xanthomonas involves ohrr, a novel organic peroxide-inducible negative regulator, and posttranscriptional modifications. | analysis of the sequence immediate upstream of ohr revealed an open reading frame, designated ohrr, with the potential to encode a 17-kda peptide with moderate amino acid sequence homology to the marr family of negative regulators of gene expression. ohrr was transcribed as bicistronic mrna with ohr, while ohr mrna was found to be 95% monocistronic and 5% bicistronic with ohrr. expression of both genes was induced by tert-butyl hydroperoxide (tbooh) treatment. high-level expression of ohrr negat ... | 2001 | 11443074 |
| structure-function analysis of bfpb, a secretin-like protein encoded by the bundle-forming-pilus operon of enteropathogenic escherichia coli. | production of type iv bundle-forming pili by enteropathogenic escherichia coli (epec) requires bfpb, an outer-membrane lipoprotein and member of the secretin protein superfamily. bfpb was found to compose a ring-shaped, high-molecular-weight outer-membrane complex that is stable in 4% sodium dodecyl sulfate at temperatures of < or = 65 degrees c. chemical cross-linking and immunoprecipitation experiments disclosed that the bfpb multimeric complex interacts with bfpg, and mutational studies showe ... | 2001 | 11466288 |
| the lipopolysaccharides of the phytopathogen xanthomonas campestris pv. campestris induce an oxidative burst reaction in cell cultures of nicotiana tabacum. | the lipopolysaccharides (lpsxcc) of the phytopathogenic bacteria xanthomonas campestris pv. campestris (x.c.c.) were purified from an exopolysaccharide-deficient mutant strain. the isolated lpsxcc induced an oxidative burst reaction in cell-suspension cultures of the non-host plant tobacco (nicotiana tabacum l.) sri. the oxidative burst elicited by lpsxcc differed from that induced by yeast elicitor (ye), a cell wall preparation of baker's yeast. the lpsxcc-induced oxidative burst was characteri ... | 2001 | 11469586 |
| polysaccharide synthesis as a carbon dissipation mechanism in metabolically uncoupled xanthomonas campestris cells. | the utilization of xanthan metabolism as an excess carbon dissipation path in xanthomonas campestris cells under sub-lethal acid stress was studied. to highlight growth limitation during metabolic uncoupling due to acid toxicity a antibiotic was added. the simultaneous addition of enoxacin and acetic acid showed that the xanthan production per unit of biomass raises with increasing concentrations of enoxacin, which seems to indicate that when the cell is prevented from growing it finds a path to ... | 2001 | 11472799 |
| assessment of the genetic diversity among strains of xanthomonas cynarae by randomly amplified polymorphic dna analysis and development of specific characterized amplified regions for the rapid identification of x. cynarae. | the randomly amplified polymorphic dna (rapd) method was used to investigate the genetic diversity in xanthomonas cynarae, which causes bacterial bract spot disease of artichoke. this rapd analysis was also intended to identify molecular markers characteristic of this species, in order to develop pcr-based markers which can be used to detect this pathogenic bacterium in artichoke fields. among the 340 rapd primers tested, 40 were selected on their ability to produce reproducible and reliable fin ... | 2001 | 11472907 |
| brown pigments produced by yarrowia lipolytica result from extracellular accumulation of homogentisic acid. | yarrowia lipolytica produces brown extracellular pigments that correlate with tyrosine catabolism. during tyrosine depletion, the yeast accumulated homogentisic acid, p-hydroxyphenylethanol, and p-hydroxyphenylacetic acid in the medium. homogentisic acid accumulated under all aeration conditions tested, but its concentration decreased as aeration decreased. with moderate aeration, equimolar concentrations of alcohol and p-hydroxyphenylacetic acid (1:1) were detected, but with lower aeration the ... | 2001 | 11472920 |
| fate of the biological control agent pseudomonas aureofaciens tx-1 after application to turfgrass. | the fate and impact of pseudomonas aureofaciens tx-1 following application as a biocontrol agent for fungi in turfgrass were studied. the organism was applied with a modified irrigation system by using a preparation containing 1 x 10(6) p. aureofaciens tx-1 cfu ml(-1) about 100 times between may and august. we examined the impact of this repeated introduction of p. aureofaciens tx-1 (which is known to produce the antimicrobial compound phenazine-1-carboxylic acid) on the indigenous microbial com ... | 2001 | 11472930 |
| characterization of stress-responsive genes, hrca-grpe-dnak-dnaj, from phytopathogenic xanthomonas campestris. | sequencing of a 6.4-kb dna fragment, cloned from the plant pathogenic bacterium xanthomonas campestris pv. campestris 17 revealed five orfs whose deduced amino acid sequences show strong similarities to the bacterial hrca, grpe, dnak, dnaj, and pdxk. the four heat shock genes are organized in the order hrca-grpe-dnak-dnaj, a genome organization found in many gram-positive bacteria, but only in one gram-negative species (xylella fastidiosa). these observations suggest that the hrca-circe system, ... | 2001 | 11479711 |
| expression of 35s::pto globally activates defense-related genes in tomato plants. | the tomato (lycopersicon esculentum) resistance gene pto confers resistance to the bacterial pathogen pseudomonas syringae pv tomato carrying the avirulent gene avrpto. overexpressing pto under the control of the cauliflower mosaic virus 35s promoter constitutively activates defense responses in the absence of pathogen infection and nonspecifically enhances disease resistance. to elucidate the mechanisms underlying this resistance, we isolated cdnas corresponding to transcripts that accumulated ... | 2001 | 11500562 |
| involvement of the tonb system in tolerance to solvents and drugs in pseudomonas putida dot-t1e. | pseudomonas putida dot-t1e is able to grow with glucose as the carbon source in liquid medium with 1% (vol/vol) toluene or 17 g of (123 mm) p-hydroxybenzoate (4hba) per liter. after random mini-tn5'phoa-km mutagenesis, we isolated the mutant dot-t1e-phoa5, which was more sensitive than the wild type to 4hba (growth was prevented at 6 g/liter) and toluene (the mutant did not withstand sudden toluene shock). susceptibility to toluene and 4hba resulted from the reduced efflux of these compounds fro ... | 2001 | 11514511 |
| quorum-sensing in gram-negative bacteria. | it has become increasingly and widely recognised that bacteria do not exist as solitary cells, but are colonial organisms that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. the languages by which bacteria communicate take the form of chemical signals, excreted from the cells, which can elicit profound physiological changes. many types of signalling molecules, which regulate diverse phenotypes across distant genera, h ... | 2001 | 11524130 |
| xanthomonas campestris pv. campestris secretes the endoglucanases engxca and engxcb: construction of an endoglucanase-deficient mutant for industrial xanthan production. | xanthomonas campestris pv. campestris secretes at least two cellulose-degrading endoglucanases. one of these endoglucanases is encoded by the engxca gene of x. c. pv. campestris 8400 that was previously characterized by gough et al. [gene (1990) 89: 53-59]. an additional endoglucanase encoded by the engxcb gene was identified in x. c. pv. campestris 8400 and fc2. the engxcb gene product that was grouped into the endoglucanase family e contains a putative n-terminal signal peptide, suggesting a s ... | 2001 | 11525621 |
| exopolysaccharides of xanthomonas pathovar strains that infect rice and wheat crops. | in order to understand the mode of action of the taxonomically related pathogens xanthomonas campestris pv. translucens, xanthomonas oryzae pv. oryzae, and xanthomonas oryzae pv. oryzicola, which attack wheat and rice crops, we examined the compositional differences of their exopolysaccharides (epss). maximum production of polysaccharide in shake cultures of these pathogens was observed between 24 and 72 h. x. campestris pv. translucens, the leaf streak pathogen of wheat, produced a higher amoun ... | 2001 | 11525629 |
| the viable but nonculturable state of ralstonia solanacearum may be involved in long-term survival and plant infection. | the role of the dormant-like viable but nonculturable (vbnc) condition in the etiology of bacterial infection was examined using a plant system. the plant-pathogenic bacterium ralstonia solanacearum was first shown to enter into the vbnc state both in response to cupric sulfate when in a saline solution and when placed in autoclaved soil. to determine if the vbnc condition is related to pathogenesis, the physiological status of bacteria recovered from different regions of inoculated tomato plant ... | 2001 | 11525979 |
| isolation of an insertion sequence from ralstonia solanacearum race 1 and its potential use for strain characterization and detection. | a new insertion sequence (is), is1405, was isolated and characterized from a ralstonia solanacearum race 1 strain by the method of insertional inactivation of the sacb gene. sequence analysis indicated that the is is closely related to the members of is5 family, but the extent of nucleotide sequence identity in 5' and 3' noncoding regions between is1405 and other members of is5 family is only 23 to 31%. nucleotide sequences of these regions were used to design specific oligonucleotide primers fo ... | 2001 | 11525989 |
| direct incorporation of glucosamine and n-acetylglucosamine into exopolymers by gluconacetobacter xylinus (=acetobacter xylinum) atcc 10245: production of chitosan-cellulose and chitin-cellulose exopolymers. | gluconacetobacter xylinus (=acetobacter xylinum) atcc 10245 incorporated 2-amino-2-deoxy-d-glucose (glucosamine) and 2-acetamido-2-deoxy-d-glucose (n-acetylglucosamine), but not 3-o-methyl-d-glucose or 2-deoxy-d-glucose into exopolymers. incorporation was confirmed by gas chromatography with and without mass spectrometry, fourier transform infrared, and 1h nuclear magnetic resonance. the average molar percentage of glucosamine and n-acetylglucosamine in the exopolymers was about 18%. | 2001 | 11525993 |
| rapid identification and differentiation of the soft rot erwinias by 16s-23s intergenic transcribed spacer-pcr and restriction fragment length polymorphism analyses. | current identification methods for the soft rot erwinias are both imprecise and time-consuming. we have used the 16s-23s rrna intergenic transcribed spacer (its) to aid in their identification. analysis by its-pcr and its-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. the its was amplified from erwinia and other genera using universal pcr primers. after pcr, the banding patterns generated allow ... | 2001 | 11526007 |
| gly gene cloning and expression and purification of glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines 8ra. | glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines, inhibits the growth of x. campestris pv. vesicatoria. we have cloned and expressed the genes encoding glycinecin a in escherichia coli. recombinant glycinecin a was purified from cell extracts by ammonium sulfate precipitation followed by chromatography on q-sepharose, mono q (ion exchange), and size exclusion columns. purified glycinecin a is composed of two polypeptides, is active over a wide ph range (6 to 9), and is ... | 2001 | 11526012 |
| the emerging periplasm-localized subclass of aroq chorismate mutases, exemplified by those from salmonella typhimurium and pseudomonas aeruginosa. | chorismate mutases of the aroq homology class are widespread in the bacteria and the archaea. many of these exist as domains that are fused with other aromatic-pathway catalytic domains. among the monofunctional aroq proteins, that from erwinia herbicola was previously shown to have a cleavable signal peptide and located in the periplasmic compartment. whether or not this might be unique to e. herbicola was unknown. | 2001 | 11532214 |
| luxarray, a high-density, genomewide transcription analysis of escherichia coli using bioluminescent reporter strains. | a sequenced collection of plasmid-borne random fusions of escherichia coli dna to a photorhabdus luminescens luxcdabe reporter was used as a starting point to select a set of 689 nonredundant functional gene fusions. this group, called luxarray 1.0, represented 27% of the predicted transcriptional units in e. coli. high-density printing of the luxarray 1.0 reporter strains to membranes on agar plates was used for simultaneous reporter gene assays of gene expression. the cellular response to nali ... | 2001 | 11544210 |
| sequence, transcriptional analysis and chromosomal location of the xanthomonas campestris pv. campestris uvrb gene. | the uvrb gene of xanthomonas campestris pv. campestris, a gram-negative plant pathogenic bacterium inhabiting soil and infected plants, was cloned and sequenced. this gene has the capacity to encode a polypeptide of 673 amino acid residues with a calculated molecular mass of 75.9 kda. its deduced amino acid sequence shows a high degree of similarity and possesses domain conservation to those of bacterial uvrb. the uvrb mutant, isolated by gene replacement, is extremely sensitive to ultraviolet i ... | 2001 | 11545271 |
| salicylic acid and ethylene pathways are differentially activated in melon cotyledons by active or heat-denatured cellulase from trichoderma longibrachiatum. | infiltration of cellulase (ec 3.2.1.4) from trichoderma longibrachiatum into melon (cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. an oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (sa) signaling pathways leading to marked induction of peroxidase and chitinase activities. the treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase an ... | 2001 | 11553761 |
| udp-glucose dehydrogenase gene of xanthomonas campestris is required for virulence. | xanthomonas campestris pv. campestris (xc) is the casual agent of black rot in crucifers. the xc gene (udgh) coding for udp-glucose dehydrogenase, an enzyme catalyzing the conversion of udp-glucose to udp-glucuronic acid, was previously shown to be required for the biosynthesis of xanthan gum, a substance necessary for the bacterium to cause disease. in this study, the transcription start site of the udgh was determined and the promoter activity monitored by the xyle reporter system indicated th ... | 2001 | 11554764 |
| novel domains of the prokaryotic two-component signal transduction systems. | the archetypal two-component signal transduction systems include a sensor histidine kinase and a response regulator, which consists of a receiver chey-like domain and a dna-binding domain. sequence analysis of the sensor kinases and response regulators encoded in complete bacterial and archaeal genomes revealed complex domain architectures for many of them and allowed the identification of several novel conserved domains, such as pas, gaf, hamp, ggdef, eal, and hd-gyp. all of these domains are w ... | 2001 | 11557134 |
| survival of salmonellae on and in tomato plants from the time of inoculation at flowering and early stages of fruit development through fruit ripening. | the fate of salmonellae applied to tomato plants was investigated. five salmonella serotypes were used to inoculate tomato plants before and after fruits set, either by injecting stems with inoculum or brushing flowers with it. ripe tomato fruits were subjected to microbiological analysis. peptone wash water, homogenates of stem scar tissues, and homogenates of fruit pulp were serially diluted and plated on bismuth sulfite agar before and after enrichment. presumptive salmonella colonies were co ... | 2001 | 11571182 |
| molecular cloning of a novel pathogen-inducible cdna encoding a putative acyl-coa synthetase from capsicum annuum l. | by means of differential display, a pool of salicylic acid (sa)-induced mrnas were identified and subsequently their cdnas were isolated from a cdna library prepared from sa-induced leaf tissues of hot pepper. one of these cdna clones, designated casig4, was 1900 bp and contained an open reading frame encoding 523 amino acids with a calculated molecular mass of 56.3 kda. the predicted amino acid sequence of casig4 showed high sequence similarity to the amp-binding protein family of both prokaryo ... | 2001 | 11575721 |
| cdna-aflp analysis unravels a genome-wide hrpg-regulon in the plant pathogen xanthomonas campestris pv. vesicatoria. | the hrp type iii protein secretion system is essential for pathogenicity of the gram-negative plant pathogen xanthomonas campestris pv. vesicatoria. expression of the hrp gene cluster is controlled by hrpg, a two-component response regulator, and hrpx, an arac-type transcriptional activator. using the cdna-aflp technique, 30 hrpg-induced (hgi) and five hrpg-repressed (hgr) cdna fragments were identified, defining a large hrpg-regulon in x. campestris pv. vesicatoria. expression of most genes in ... | 2001 | 11580833 |
| fastidian gum: the xylella fastidiosa exopolysaccharide possibly involved in bacterial pathogenicity. | the gram-negative bacterium xylella fastidiosa was the first plant pathogen to be completely sequenced. this species causes several economically important plant diseases, including citrus variegated chlorosis (cvc). analysis of the genomic sequence of x. fastidiosa revealed a 12 kb dna fragment containing an operon closely related to the gum operon of xanthomonas campestris. the presence of all genes involved in the synthesis of sugar precursors, existence of exopolysaccharide (eps) production r ... | 2001 | 11583843 |
| lipopolysaccharide biosynthesis in xanthomonas campestris pv. campestris: a cluster of 15 genes is involved in the biosynthesis of the lps o-antigen and the lps core. | as a result of mutational and dna sequence analysis, a wxc gene cluster involved in the synthesis of the surface lipopolysaccharide (lps) was identified in xanthomonas campestris pv. campestris. this gene cluster comprises 15 genes. it was located on a cloned 35-kb fragment of chromosomal dna, close, but not directly adjacent, to previously characterized genes for lps biosynthesis. the g + c content of all but one of the wxc genes was atypically low for x. campestris pv. campestris, while the g ... | 2001 | 11589581 |
| family of class 1 integrons related to in4 from tn1696. | the class 1 integron in28, found in the multidrug resistance transposon tn1403, was found to be located in the res site of the backbone transposon and is flanked by a 5-bp direct duplication, indicating that it reached this position by transposition. in28 has a backbone structure related to that of in4, but has lost internal sequences, including the sul1 gene, due to an is6100-mediated deletion. in28 also lacks the partial copy of is6100 found in in4 and contains different gene cassettes, blap1, ... | 2001 | 11600350 |
| concentrations of copper thought to be toxic to escherichia coli can induce the viable but nonculturable condition. | we have determined that concentrations of copper considered to be toxic can induce a fraction of a population of escherichia coli to enter the viable but nonculturable (vbnc) condition. copper-induced vbnc cells could be resuscitated for up to 2 weeks after entering the vbnc state. | 2001 | 11679363 |
| dimethoxyphenol oxidase activity of different microbial blue multicopper proteins. | 2,6-dimethoxyphenol is a versatile substrate for pyricularia oryzae laccase, ppoa from marinomonas mediterranea, phenoxazinone synthase from streptomyces antibioticus and mammalian ceruloplasmin. in addition, in cellular extracts of microorganisms expressing other blue multicopper proteins with no enzymatic activity previously described, such as escherichia coli (copper resistance cueo), pseudomonas syringae and xanthomonas campestris (copper resistance copa), bacillus subtilis (sporulation prot ... | 2001 | 11682198 |
| comparative evaluation of pectolytic and proteolytic enzyme production by free and immobilized cells of some strains of the phytopathogenic erwinia chrysanthemi. | whole cells of the phytopathogenic erwinia chrysanthemi strains were immobilized in k-carrageenan and grown in high-calcium xanthomonas campestris medium containing sodium polypectate as carbon source. all the strains used survived immobilization into k-carrageenan beads. immobilized e. chrysanthemi strains displayed higher pectolytic and proteolytic enzyme activities than free cells in liquid suspension. carrageenan immobilization techniques could provide a system to mimic the conditions of e. ... | 2001 | 11687933 |
| controlled expression in klebsiella pneumoniae and shigella flexneri using a bacteriophage p1-derived c1-regulated promoter system. | the utility of promoters regulated by the bacteriophage p1 temperature-sensitive c1 repressor was examined in shigella flexneri and klebsiella pneumoniae. promoters carrying c1 operator sites driving lacz expression had induction/repression ratios of up to 240-fold in s. flexneri and up to 50-fold in k. pneumoniae. the promoters exhibited remarkably low basal expression, demonstrated modulation by temperature, and showed rapid induction. this system will provide a new opportunity for controlled ... | 2001 | 11698385 |
| the lexa protein from deinococcus radiodurans is not involved in reca induction following gamma irradiation. | the involvement of lexa in induction of reca was investigated in deinococcus radiodurans. as in the wild-type strain, an increase in reca protein synthesis following gamma irradiation was detected in a lexa disruptant, indicating that lexa is not involved in the induction of reca in d. radiodurans. | 2001 | 11698386 |
| brucella abortus genes identified following constitutive growth and macrophage infection. | the chronicity of brucella abortus infection in humans and animals depends on the organism's ability to escape host defenses by gaining entry and surviving inside the macrophage. although no human vaccine exists for brucella, vaccine development in other bacteria has been based on deletions of selective nutritional as well as regulatory systems. our goal is to develop a vaccine for brucella. to further this aim, we have used a green fluorescent protein (gfp) reporter system to identify constitut ... | 2001 | 11705955 |
| induction of a pepper cdna encoding sar8.2 protein during the resistance response to tobacco mosaic virus. | a cdna library was constructed with mrna extracted from tmv resistant hot pepper plants 24 and 48 h after inoculation by tmv. the library was screened differentially with radio-labeled cdna synthesized with mrna from the leaves of either tmv-inoculated or mock-inoculated hot pepper plants. casar8.2 clone was one of the clones isolated by this differential screening. the predicted amino acid sequence of casar8.2 has a homology of 52% similarity to that of tobacco sar8.2 genes. southern blot analy ... | 2001 | 11710530 |
| alkyl hydroperoxide reductase is the primary scavenger of endogenous hydrogen peroxide in escherichia coli. | hydrogen peroxide is generated during aerobic metabolism and is capable of damaging critical biomolecules. however, mutants of escherichia coli that are devoid of catalase typically exhibit no adverse phenotypes during growth in aerobic media. we discovered that catalase mutants retain the ability to rapidly scavenge h(2)o(2) whether it is formed internally or provided exogenously. analysis of candidate genes revealed that the residual activity is due to alkyl hydroperoxide reductase (ahp). muta ... | 2001 | 11717276 |
| regulation of the synthesis of cyclic glucan in xanthomonas campestris by a diffusible signal molecule. | the rpf gene cluster of xanthomonas campestris pv. campestris is involved in the co-ordinate positive regulation of the production of extracellular enzymes and the extracellular polysaccharide xanthan. several of the rpf genes are involved in a regulatory system involving the small diffusible molecule dsf (for diffusible signal factor). synthesis of dsf requires rpff, and a two-component sensory transduction system involving rpfc has been implicated in the perception of the signal and signal tra ... | 2001 | 11734884 |
| 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 |
| type iii secretion and in planta recognition of the xanthomonas avirulence proteins avrbs1 and avrbst. | summary the hrp gene cluster of the plant pathogen xanthomonas campestris pv. vesicatoria (xcv) encodes a type iii secretion system required for the delivery of virulence and avirulence proteins into the plant. some of these effector proteins, e.g. avrbs1 and avrbst, are recognized by pepper plants carrying corresponding resistance genes, triggering the hypersensitive reaction (hr). in this study, epitope tagged avrbs1 and avrbst proteins were detected in culture supernatants only in the presenc ... | 2001 | 20573017 |
| antimicrobial activity of culture filtrate of bacillus amyloliquefaciens rc-2 isolated from mulberry leaves. | abstract a potential antagonist, bacillus amyloliquefaciens strain rc-2, against colletotrichum dematium, mulberry anthracnose fungus, was obtained from healthy mulberry leaves by in vitro and in vivo screening techniques. application of culture filtrate of rc-2 inhibited disease on mulberry leaves, indicating that suppression was due to antifungal compounds in the filtrate. development of mulberry anthracnose on mulberry leaves was inhibited only when the culture filtrate was applied before fun ... | 2001 | 18944392 |
| identification and origin of xanthomonas campestris pv. campestris races and related pathovars. | abstract one hundred sixty-four isolates of xanthomonas campestris pv. campestris and other x. campestris pathovars known to infect cruciferous hosts (x. campestris pvs. aberrans, raphani, armoraciae, and incanae) were inoculated onto a differential series of brassica spp. to determine both pathogenicity to brassicas and race. of these, 144 isolates were identified as x. campestris pv. campestris and grouped into six races, with races 1 (62%) and 4 (32%) being predominant. other races were rare. ... | 2001 | 18943594 |
| characterization and antimicrobial activity of erbium(iii) complexes of c-3 substituted 2-hydroxy-1,4-naphthalenedione-1-oxime derivatives. | erbium(iii) complexes of 2-hydroxy-l,4-naphthalenedione-1-oxime and its c-3 substituted derivatives are synthesized and characterized by elemental analysis, thermogravimetric analysis, infrared spectroscopy, magnetic susceptibility measurements 2-hydroxy-1,4-naphthalenedione-1-oxime derivatives are analysed using (1)h and (13)c nmr spectroscopy. the molecular composition of the synthesized complexes is found to be [ml(3)(h(2)o)(2)]. the antimicrobial activity of these complexes is determined by ... | 2001 | 18475990 |
| type ii secretion and pathogenesis. | 2001 | 11349009 | |
| the tasty locus on chromosome 1 of arabidopsis affects feeding of the insect herbivore trichoplusia ni. | the generalist insect herbivore trichoplusia ni (cabbage looper) readily consumes arabidopsis and can complete its entire life cycle on this plant. natural isolates (ecotypes) of arabidopsis are not equally susceptible to t. ni feeding. while some are hardly touched by t. ni, others are eaten completely to the ground. comparison of two commonly studied arabidopsis ecotypes in choice experiments showed that columbia is considerably more resistant than landsberg erecta. in no-choice experiments, w ... | 2001 | 11402216 |
| oligoguluronates elicit an oxidative burst in the brown algal kelp laminaria digitata. | oligomeric degradation products of alginate elicited a respiratory and oxidative burst in the sporophytes of the kelp laminaria digitata. the generation of activated oxygen species (aos), o(2)(-), and h(2)o(2) was detected at the single cell level, using nitroblue tetrazolium precipitation and a redox-sensitive fluorescent probe, respectively. the oxidative burst involved diphenyleneiodonium-sensitive aos-generating machinery and its amplitude depended on the type of tissue. after a first elicit ... | 2001 | 11154336 |
| agricultural microbes genome 2: first glimpses into the genomes of plant-associated microbes. | 2001 | 11251088 | |
| interactions between xanthomonas species and arabidopsis thaliana. | arabidopsis has been well studied as a model plant for plant pathogen interactions. while a large portion of the literature has been devoted to interactions between arabidopsis and pseudomonas and peronospora species, a small cadre of researchers have been making inroads on the response of arabidopsis to xanthomonas. differential responses of arabidopsis accessions to isolates of xanthomonas campestris pv campestris include tolerance, a hypersensitive response, resistance without a hypersensitiv ... | 2002 | 22303203 |
| using genomic resources to guide research directions. the arabinogalactan protein gene family as a test case. | arabinogalactan proteins (agps) are extracellular hydroxyproline-rich proteoglycans implicated in plant growth and development. the protein backbones of agps are rich in proline/hydroxyproline, serine, alanine, and threonine. most family members have less than 40% similarity; therefore, finding family members using basic local alignment search tool searches is difficult. as part of our systematic analysis of agp function in arabidopsis, we wanted to make sure that we had identified most of the m ... | 2002 | 12177459 |
| ethylene biosynthesis and signaling networks. | 2002 | 12045274 | |
| ethylene synthesis regulated by biphasic induction of 1-aminocyclopropane-1-carboxylic acid synthase and 1-aminocyclopropane-1-carboxylic acid oxidase genes is required for hydrogen peroxide accumulation and cell death in ozone-exposed tomato. | we show that above a certain threshold concentration, ozone leads to leaf injury in tomato (lycopersicon esculentum). ozone-induced leaf damage was preceded by a rapid increase in 1-aminocyclopropane-1-carboxylic acid (acc) synthase activity, acc content, and ethylene emission. changes in mrna levels of specific acc synthase, acc oxidase, and ethylene receptor genes occurred within 1 to 5 h. expression of the genes encoding components of ethylene biosynthesis and perception, and biochemistry of ... | 2002 | 12481074 |
| the phage proteomic tree: a genome-based taxonomy for phage. | there are approximately 10(31) phage in the biosphere, making them the most abundant biological entities on the planet. despite their great numbers and ubiquitous presence, very little is known about phage biodiversity, biogeography, or phylogeny. information is limited, in part, because the current ictv taxonomical system is based on culturing phage and measuring physical parameters of the free virion. no sequence-based taxonomic systems have previously been established for phage. we present he ... | 2002 | 12142423 |
| mob psychology. | 2002 | 11807045 | |
| four near-isogenic lines of cotton with different genes for bacterial blight resistance. | abstract the development and genetic characterization of four near-isogenic lines (nils) of cotton (gossypium hirsutum) is described herein. each line contains a single, but different, gene for resistance to bacterial blight caused by xanthomonas campestris pv. malvacearum. the lines were derived using at least six backcrosses to the susceptible recurrent parent 'acala 44', followed by single plant-progeny row selection for uniformity. the nils are homozygous for the b(2), b(4), b(in), or b(7) g ... | 2002 | 18943887 |
| sources and origin of resistance to xanthomonas campestris pv. campestris in brassica genomes. | abstract two hundred and seventy-six accessions of mainly brassica spp. were screened for resistance to xanthomonas campestris pv. campestris races. in brassica oleracea (c genome), the majority of accessions were susceptible to all races, but 43% showed resistance to one or more of the rare races (2, 3, 5, and 6) and a single accession showed partial resistance to races 1, 3, 5, and 6. further searches for resistance to races 1 and 4, currently the most important races worldwide, and race 6, th ... | 2002 | 18944146 |
| inheritance of race-specific resistance to xanthomonas campestris pv. campestris in brassica genomes. | abstract the inheritance of resistance to three xanthomonas campestris pv. campestris races was studied in crosses between resistant and susceptible lines of brassica oleracea (c genome), b. carinata (bc genome), and b. napus (ac genome). resistance to race 3 in the b. oleracea doubled haploid line boh 85c and in pi 436606 was controlled by a single dominant locus (xca3). resistance to races 1 and 3 in the b. oleracea line badger inbred-16 was quantitative and recessive. strong resistance to rac ... | 2002 | 18944224 |
| transduction-mediated transfer of unmarked deletion and point mutations through use of counterselectable suicide vectors. | a challenge in strain construction is that unmarked deletion and nucleotide substitution alleles generally do not confer selectable phenotypes. we describe here a rapid and efficient strategy for transferring such alleles via generalized transduction. the desired allele is first constructed and introduced into the chromosome by conventional allelic-exchange methods. the suicide vector containing the same allele is then integrated into the mutant chromosome, generating a tandem duplication homozy ... | 2002 | 11741872 |
| identification of a gene essential for sheathed structure formation in sphaerotilus natans, a filamentous sheathed bacterium. | sphaerotilus natans, a filamentous bacterium that causes bulking in activated sludge processes, can assume two distinct morphologies, depending on the substrate concentration for growth; in substrate-rich media it grows as single rod-shaped cells, whereas in substrate-limited media it grows as filaments. to identify genes responsible for sheath formation, we carried out transposon tn5 mutagenesis. of the approximately 20,000 mutants obtained, 7 did not form sheathed structures. sequencing of the ... | 2002 | 11772646 |
| detection of the plant pathogenic bacterium xanthomonas campestris pv. campestris in seed extracts of brassica sp. applying fluorescent antibodies and flow cytometry. | xanthomonas campestris pv. campestris (xcc) is a seed-transmitted plant pathogenic bacterium that causes black rot of crucifers. seed lots and plants are screened for contamination with this pathogen using plating or serological assays. these methods, however, are time consuming and not very sensitive, respectively. therefore, flow cytometry (fcm) was evaluated as a tool for the rapid detection and quantification of xcc cells labeled with a mixture of specific fluorescein isothicyanate (fitc)-mo ... | 2002 | 11813202 |
| molecular analyses of the natural transformation machinery and identification of pilus structures in the extremely thermophilic bacterium thermus thermophilus strain hb27. | thermus thermophilus hb27, an extremely thermophilic bacterium, exhibits high competence for natural transformation. to identify genes of the natural transformation machinery of t. thermophilus hb27, we performed homology searches in the partially completed t. thermophilus genomic sequence for conserved competence genes. these analyses resulted in the detection of 28 open reading frames (orfs) exhibiting significant similarities to known competence proteins of gram-negative and gram-positive bac ... | 2002 | 11823215 |
| biosynthesis of a substituted cellulose from a mutant strain of xanthomonas campestris. | in xanthomonas campestris the genes involved in polysaccharide (xanthan) biosynthesis are located in a gene cluster (gum) of 16 kb. a tn5 insertion mutant with a reduced slimy phenotype has been characterized. this mutant failed to produce the pentasaccharide repeating-unit of xanthan. only three sugars were transferred to the prenyl phosphate intermediate. several lines of evidence suggested that the lipid-associated saccharide was the trisaccharide reducing end of the pentasaccharide from the ... | 2002 | 11841812 |
| two novel type iii-secreted proteins of xanthomonas campestris pv. vesicatoria are encoded within the hrp pathogenicity island. | the hrp type iii protein secretion system (ttss) is essential for pathogenicity of gram-negative plant pathogen xanthomonas campestris pv. vesicatoria. cdna-amplified fragment length polymorphism and reverse transcription-pcr analyses identified new genes, regulated by key hrp regulator hrpg, in the regions flanking the hrp gene cluster. sequence analysis revealed genes encoding hpag, a predicted leucine-rich repeat-containing protein, the lysozyme-like hpah protein, and xopa and xopd, which are ... | 2002 | 11844763 |
| mutation in the xanthomonas campestris xana gene required for synthesis of xanthan and lipopolysaccharide drastically reduces the efficiency of bacteriophage (phi)l7 adsorption. | (phi)l7 is a lytic phage infecting the gram-negative xanthomonas campestis pv. campestris, a plant pathogen. to study phage-host interaction, a (phi)l7-resistant mutant was isolated from strain xc17 by mini-tn5 transposition and designated ch7lr. ch7lr could not plate (phi)l7 in double-layered assay and formed turbid clearing zones when the cell lawn was dropped with a high titer of (phi)l7. sequence analysis showed that the mutated gene is xana coding for phosphoglucomutase/phosphomannomutase, ... | 2002 | 11846409 |
| genomewide identification of pseudomonas syringae pv. tomato dc3000 promoters controlled by the hrpl alternative sigma factor. | the ability of pseudomonas syringae pv. tomato dc3000 to parasitize tomato and arabidopsis thaliana depends on genes activated by the hrpl alternative sigma factor. to support various functional genomic analyses of dc3000, and specifically, to identify genes involved in pathogenesis, we developed a draft sequence of dc3000 and used an iterative process involving computational and gene expression techniques to identify virulence-implicated genes downstream of hrpl-responsive promoters. hypersensi ... | 2002 | 11854524 |
| induction of pepper cdna encoding a lipid transfer protein during the resistance response to tobacco mosaic virus. | pepper (capsicum annuum) plants exhibit hypersensitive response (hr) against infection by many tobamoviruses. a clone encoding a putative nonspecific lipid transfer protein (caltp1) was isolated by differential screening of a cdna library from resistant pepper leaves when inoculated with tobacco mosaic virus (tmv) pathotype p0. the predicted amino acid sequence of caltp1 is highly similar to that of the other plant ltps. southern blot analysis showed that a small gene family of ltp-related seque ... | 2002 | 11855726 |
| differential effectiveness of salicylate-dependent and jasmonate/ethylene-dependent induced resistance in arabidopsis. | salicylic acid (sa), jasmonic acid (ja), and ethylene (et) are each involved in the regulation of basal resistance against different pathogens. these three signals play important roles in induced resistance as well. sa is a key regulator of pathogen-induced systemic acquired resistance (sar), whereas ja and et are required for rhizobacteria-mediated induced systemic resistance (isr). both types of induced resistance are effective against a broad spectrum of pathogens. in this study, we compared ... | 2002 | 11858171 |
| synthesis of an xylosylated rhamnose pentasaccharide, the repeating unit of the o-chain polysaccharide of the lipopolysaccharide of xanthomonas campestris pv. begoniae gspb 525. | a xylosylated rhamnose pentasaccharide, alpha-l-rhap-(1-->3)-[beta-l-xylp-(1-->2)-]-alpha-l-rhap-(1-->3)-[beta-l-xylp-(1-->4)]-l-rhap, the repeating unit of the o-chain polysaccharide (ops) of the lipopolysaccharides of xanthomonas campestris pv. begoniae gspb 525 was synthesized by a highly regio- and stereoselective way. thus coupling of 1,2-o-ethylidene-beta-l-rhamnopyranose (1) with 2,3,4-tri-o-benzoyl-alpha-l-rhamnopyranosyl trichloroacetimidate (2) to give (1-->3)-linked disaccharide (3), ... | 2002 | 11861012 |
| genetic relationship among worldwide strains of xanthomonas causing canker in citrus species and design of new primers for their identification by pcr. | partial sequence analysis of the ribosomal operon in xanthomonas axonopodis allowed discrimination among strains causing the a, b, and c types of citrus bacterial canker (cbc) and quantification of the relationship of these organisms with other species and pathovars in the same genus. sets of primers based on sequence differences in the internally transcribed spacer and on a sequence from the plasmid gene ptha involved in virulence were designed for specific identification of xanthomonads causin ... | 2002 | 11872476 |
| effects of t4 lysozyme release from transgenic potato roots on bacterial rhizosphere communities are negligible relative to natural factors. | rhizosphere bacterial communities of two transgenic potato lines which produce t4 lysozyme for protection against bacterial infections were analyzed in comparison to communities of wild-type plants and transgenic controls not harboring the lysozyme gene. rhizosphere samples were taken from young, flowering, and senescent plants at two field sites in three consecutive years. the communities were characterized in a polyphasic approach. cultivation-dependent methods included heterotrophic plate cou ... | 2002 | 11872484 |
| reduction of olive knot disease by a bacteriocin from pseudomonas syringae pv. ciccaronei. | a bacteriocin produced by pseudomonas syringae pv. ciccaronei, used at different purification levels and concentrations in culture and in planta, inhibited the multiplication of p. syringae subsp. savastanoi, the causal agent of olive knot disease, and affected the epiphytic survival of the pathogen on the leaves and twigs of treated olive plants. treatments with bacteriocin from p. syringae pv. ciccaronei inhibited the formation of overgrowths on olive plants caused by p. syringae subsp. savast ... | 2002 | 11872493 |
| mutational analysis of the tonb1 energy coupler of pseudomonas aeruginosa. | siderophore-mediated iron transport in pseudomonas aeruginosa is dependent upon the cytoplasmic membrane-associated tonb1 energy coupling protein for activity. to assess the functional significance of the various regions of this molecule and to identify functionally important residues, the tonb1 gene was subjected to site-directed mutagenesis, and the influence on iron acquisition was determined. the novel n-terminal extension of tonb1, which is absent in all other examples of tonb, was required ... | 2002 | 11872700 |
| a two-component regulator mediates population-density-dependent expression of the bradyrhizobium japonicum nodulation genes. | bradyrhizobium japonicum nod gene expression was previously shown to be population density dependent. induction of the nod genes is highest at low culture density and repressed at high population densities. this repression involves both nola and nodd2 and is mediated by an extracellular factor found in b. japonicum conditioned medium. nola and nodd2 expression is maximal at high population densities. we demonstrate here that a response regulator, encoded by nwsb, is required for the full express ... | 2002 | 11872728 |
| age-related resistance in arabidopsis is a developmentally regulated defense response to pseudomonas syringae. | age-related resistance (arr) has been observed in a number of plant species; however, little is known about the biochemical or molecular mechanisms involved in this response. arabidopsis becomes more resistant, or less susceptible, to virulent pseudomonas syringae (pv tomato or maculicola) as plants mature (in planta bacterial growth reduction of 10- to 100-fold). an arr-like response also was observed in response to certain environmental conditions that accelerate arabidopsis development. arr o ... | 2002 | 11884688 |
| molecular analysis of the gene encoding a novel chitin-binding protease from alteromonas sp. strain o-7 and its role in the chitinolytic system. | alteromonas sp. strain o-7 secretes several proteins in response to chitin induction. we have found that one of these proteins, designated apriv, is a novel chitin-binding protease involved in chitinolytic activity. the gene encoding apriv (apriv) was cloned in escherichia coli. dna sequencing analysis revealed that the open reading frame of apriv encoded a protein of 547 amino acids with a calculated molecular mass of 57,104 da. apriv is a modular enzyme consisting of five domains: the signal s ... | 2002 | 11889092 |
| the cytochrome c maturation locus of legionella pneumophila promotes iron assimilation and intracellular infection and contains a strain-specific insertion sequence element. | previously, we obtained a legionella pneumophila mutant, nu208, that is hypersensitive to iron chelators when grown on standard legionella media. here, we demonstrate that nu208 is also impaired for growth in media that simply lack their iron supplement. the mutant was not, however, impaired for the production of legiobactin, the only known l. pneumophila siderophore. importantly, nu208 was also highly defective for intracellular growth in human u937 cell macrophages and hartmannella and acantha ... | 2002 | 11895946 |
| characterization and toxicity of amanita cokeri extract. | the nonprotein amino acids 2-amino-3-cyclopropylbutanoic acid and 2-amino-5-chloro-4-pentenoic acid were isolated from the mushroom amanita cokeri. the cyclopropyl amino acid is toxic to the fungus cercospora kikuchii, the arthropod oncopeltus fasciatus (milk weed bug), and the bacteria agrobacterium tumefaciens, erwinia amylovora, and xanthomonas campestris. toxicity to bacteria was reversible by addition of isoleucine to the medium. no toxicity was observed for 2-amino-5-chloro-4-pentenoic aci ... | 2002 | 11925071 |
| genetic control of quorum-sensing signal turnover in agrobacterium tumefaciens. | a signal turnover system is an essential component of many genetic regulatory mechanisms. the best-known example is the ubiquitin-dependent protein degradation system that exists in many organisms. we found that agrobacterium tumefaciens adopts a unique signal turnover system to control exiting from a quorum-sensing mode. a. tumefaciens regulates ti plasmid conjugal transfer by a quorum-sensing signal, n-3-oxo-octanoyl homoserine lactone (3oc8hsl), also known as agrobacterium autoinducer. by usi ... | 2002 | 11930013 |
| phylogenetic analysis of xanthomonas species based upon 16s-23s rdna intergenic spacer sequences. | phylogenetic relationships of 17 species of xanthomonas were assessed based on analysis of 16s-23s rdna intergenic spacer (its) sequences; a higher level of resolution was obtained than that revealed by 16s rdna analysis. its sequences varied in size from 492 to 578 nt within the genus and the similarity among sequences ranged from 63 to 99%. major differences were found for the hyacinthi group, which included xanthomonas albilineans, xanthomonas hyacinthi, xanthomonas sacchari, xanthomonas thei ... | 2002 | 11931143 |