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tracking the subtle mutations driving host sensing by the plant pathogen streptomyces scabies.the acquisition of genetic material conferring the arsenal necessary for host virulence is a prerequisite on the path to becoming a plant pathogen. more subtle mutations are also required for the perception of cues signifying the presence of the target host and optimal conditions for colonization. the decision to activate the pathogenic lifestyle is not "taken lightly" and involves efficient systems monitoring environmental conditions. but how can a pathogen trigger the expression of virulence g ...201728261670
emergence of novel pathogenic streptomyces species by site-specific accretion and cis-mobilization of pathogenicity islands.the main pathogenicity factor of streptomyces species associated with the potato common scab disease is a nitrated diketopiperazine called thaxtomin a (thxa). in streptomyces scabiei (syn. s. scabies), which is thought to be the most ancient pathogenic streptomyces species, the thxa biosynthetic cluster is located within a mobile genomic island called the toxicogenic region (tr). three attachment (att) sites further separate tr into two subregions (tr1 and tr2). tr1 contains the thxa biosyntheti ...201727977935
physical, chemical and proteomic evidence of potato suberin degradation by the plant pathogenic bacterium streptomyces scabiei.potato peels consist of a tissue called phellem, which is formed by suberized cell layers. the degradation of suberin, a lipidic and recalcitrant polymer, is an ecological process attributed to soil fungal populations; however, previous studies have suggested that streptomyces scabiei, the causal agent of potato common scab, possesses the ability to degrade suberin. in the present study, s. scabiei was grown in medium containing suberin-enriched potato phellem as the sole carbon source and its s ...201627853060
enzymatic hydrolysis by transition-metal-dependent nucleophilic aromatic substitution.nitroaromatic compounds are typically toxic and resistant to degradation. bradyrhizobium species strain js329 metabolizes 5-nitroanthranilic acid (5naa), which is a molecule secreted by streptomyces scabies, the plant pathogen responsible for potato scab. the first biodegradation enzyme is 5naa-aminohydrolase (5naa-a), a metalloprotease family member that converts 5naa to 5-nitrosalicylic acid. we characterized 5naa-a biochemically and obtained snapshots of its mechanism. 5naa-a, an octamer that ...201627694799
a whole genome analysis reveals the presence of a plant pr1 sequence in the potato pathogen streptomyces scabies and other streptomyces species.streptomyces scabies is a common soil bacterium that causes scab symptoms in potatoes. strong evidence indicates horizontal gene transfer (hgt) among bacteria has influenced the evolution of this plant pathogen and other streptomyces spp. to extend the study of the hgt to the streptomyces genus, we explored the effects of the inter-domain hgt in the s. scabies genome. we employed a semi-automatic pipeline based on blastp searches and phylogenetic reconstruction. the data show low impact of inter ...201627530704
promiscuous pathogenicity islands and phylogeny of pathogenic streptomyces spp.approximately 10 streptomyces species cause disease on underground plant structures. the most economically important of these is potato scab, and the most studied of these pathogens is streptomyces scabiei (syn. s. scabies). the main pathogenicity determinant of scab-causing streptomyces species is a nitrated diketopiperazine, known as thaxtomin a (thxa). in the pathogenic species streptomyces turgidiscabies, thxa biosynthetic genes reside on a mobile pathogenicity island (pai). however, the mob ...201627502745
the cebe/msik transporter is a doorway to the cello-oligosaccharide-mediated induction of streptomyces scabies pathogenicity.streptomyces scabies is an economically important plant pathogen well-known for damaging root and tuber crops by causing scab lesions. thaxtomin a is the main causative agent responsible for the pathogenicity of s. scabies and cello-oligosaccharides are environmental triggers that induce the production of this phytotoxin. how cello-oligosaccharides are sensed or transported in order to induce the virulent behavior of s. scabies? here we report that the cellobiose and cellotriose binding protein ...201627250236
rice bran amendment suppresses potato common scab by increasing antagonistic bacterial community levels in the rhizosphere.potato common scab (pcs), caused by pathogenic streptomyces spp., is a serious disease in potato production worldwide. cultural practices, such as optimizing the soil ph and irrigation, are recommended but it is often difficult to establish stable disease reductions using these methods. traditionally, local farmers in southwest japan have amended soils with rice bran (rb) to suppress pcs. however, the scientific mechanism underlying disease suppression by rb has not been elucidated. the present ...201627050572
scabin, a novel dna-acting adp-ribosyltransferase from streptomyces scabies.a bioinformatics strategy was used to identify scabin, a novel dna-targeting enzyme from the plant pathogen 87.22 strain of streptomyces scabies scabin shares nearly 40% sequence identity with the pierisin family of mono-adp-ribosyltransferase toxins. scabin was purified to homogeneity as a 22-kda single-domain enzyme and was shown to possess high nad(+)-glycohydrolase (km (nad) = 68 ± 3 μm; kcat = 94 ± 2 min(-1)) activity with an rsqxe motif; it was also shown to target deoxyguanosine and showe ...201627002155
toughing it out--disease-resistant potato mutants have enhanced tuber skin defenses.common scab, a globally important potato disease, is caused by infection of tubers with pathogenic streptomyces spp. previously, disease-resistant potato somaclones were obtained through cell selections against the pathogen's toxin, known to be essential for disease. further testing revealed that these clones had broad-spectrum resistance to diverse tuber-invading pathogens, and that resistance was restricted to tuber tissues. the mechanism of enhanced disease resistance was not known. tuber per ...201626780437
hybprobes-based real-time pcr assay for specific identification of streptomyces scabies and streptomyces europaeiscabiei, the potato common scab pathogens.the aim of this study was to develop and validate a hybprobes-based real-time pcr assay targeting the trpb gene for specific identification of streptomyces scabies and streptomyces europaeiscabiei. four primer pairs and a fluorescent probe were designed and evaluated for specificity in identifying s. scabies and streptomyces europaeiscabiei, the potato common scab pathogens. the specificity of the hybprobes-based real-time pcr assay was evaluated using 46 bacterial strains, 23 streptomyces strai ...201626551004
draft genome sequences of streptomyces scabiei s58, streptomyces turgidiscabies t45, and streptomyces acidiscabies a10, the pathogens of potato common scab, isolated in japan.the draft genome sequences of the three pathogens of potato common scab, streptomyces scabiei s58, streptomyces turgidiscabies t45, and streptomyces acidiscabies a10, isolated in japan, are presented here. the genome size of each strain is >10 mb, and the three pathogenic strains share genes located in a pathogenicity island previously described in other pathogenic streptomyces species.201626941144
identification of genetic and environmental factors stimulating excision from streptomyces scabiei chromosome of the toxicogenic region responsible for pathogenicity.the genes conferring pathogenicity in streptomyces turgidiscabies, a pathogen causing common scab of potato, are grouped together on a pathogenicity island (pai), which has been found to be mobile and appears to transfer and disseminate like an integrative and conjugative element (ice). however, in streptomyces scabiei, another common scab-inducing species, the pathogenicity genes are clustered in two regions: the toxicogenic region (tr) and the colonization region. the s. scabiei 87.22 genome w ...201626177341
genome content and phylogenomics reveal both ancestral and lateral evolutionary pathways in plant-pathogenic streptomyces species.streptomyces spp. are highly differentiated actinomycetes with large, linear chromosomes that encode an arsenal of biologically active molecules and catabolic enzymes. members of this genus are well equipped for life in nutrient-limited environments and are common soil saprophytes. out of the hundreds of species in the genus streptomyces, a small group has evolved the ability to infect plants. the recent availability of streptomyces genome sequences, including four genomes of pathogenic species, ...201626826232
18β-glycyrrhetinic acid derivatives possessing a trihydroxylated a ring are potent gram-positive antibacterial agents.the oleanane-type triterpene 18β-glycyrrhetinic acid (1) was modified chemically through the introduction of a trihydroxylated a ring and an ester moiety at c-20 to enhance its antibacterial activity. compounds 22, 23, 25, 28, 29, 31, and 32 showed more potent inhibitory activity against streptomyces scabies than the positive control, streptomycin. additionally, the inhibitory activity of the most potent compound, 29, against bacillus subtilis, staphylococcus aureus, and methicillin-resistant st ...201626928299
taxonomic evaluation of putative streptomyces scabiei strains held in the ars culture collection (nrrl) using multi-locus sequence analysis.multi-locus sequence analysis has been demonstrated to be a useful tool for identification of streptomyces species and was previously applied to phylogenetically differentiate the type strains of species pathogenic on potatoes (solanum tuberosum l.). the ars culture collection (nrrl) contains 43 strains identified as streptomyces scabiei deposited at various times since the 1950s and these were subjected to multi-locus sequence analysis utilising partial sequences of the house-keeping genes atpd ...201626739474
genetics and genomics of the genus amycolatopsis.actinobacteria are gram-positive filamentous bacteria which contains some of the most deadly human pathogens (mycobacterium tuberculosis, m. leprae, corynebacterium diphtheriae, nocardia farcinica), plant pathogens (streptomyces scabies, leifsonia xyli) along with organisms that produces antibiotic (streptomycetes, amycolatopsis, salinospora). interestingly, these bacteria are equipped with an extraordinary capability of producing antibiotics and other metabolites which have medicinal properties ...201627407288
biocontrol of potato common scab is associated with high pseudomonas fluorescens lbum223 populations and phenazine-1-carboxylic acid biosynthetic transcript accumulation in the potato geocaulosphere.pseudomonads are often used as biocontrol agents because they display a broad range of mechanisms to control diseases. common scab of potato, caused by streptomyces scabies, was previously reported to be controlled by pseudomonas fluorescens lbum223 through phenazine-1-carboxylic acid (pca) production. in this study, we aimed at characterizing the population dynamics of lbum223 and the expression of phzc, a key gene involved in the biosynthesis of pca, in the rhizosphere and geocaulosphere of po ...201627088392
production of the streptomyces scabies coronafacoyl phytotoxins involves a novel biosynthetic pathway with an f420 -dependent oxidoreductase and a short-chain dehydrogenase/reductase.coronafacoyl phytotoxins are secondary metabolites that are produced by various phytopathogenic bacteria, including several pathovars of the gram-negative bacterium pseudomonas syringae as well as the gram-positive potato scab pathogen streptomyces scabies. the phytotoxins are composed of the polyketide coronafacic acid (cfa) linked via an amide bond to amino acids or amino acid derivatives, and their biosynthesis involves the cfa and cfa-like gene clusters that are found in p. syringae and s. s ...201626991928
characterization of the coronatine-like phytotoxins produced by the common scab pathogen streptomyces scabies.streptomyces scabies is an important causative agent of common scab disease of potato tubers and other root crops. the primary virulence factor produced by this pathogen is a phytotoxic secondary metabolite called thaxtomin a, which is essential for disease development. in addition, the genome of s. scabies harbors a virulence-associated biosynthetic gene cluster called the coronafacic acid (cfa)-like gene cluster, which was previously predicted to produce metabolites that resemble the pseudomon ...201525423263
chemical composition and antibacterial activity of methanolic extract and essential oil of iranian teucrium polium against some of phytobacteria.the antibacterial activity of essential oil and methanolic extract of teucrium polium was determined against pseudomonas aeruginosa, pantoea agglomerans, brenneria nigrifluens, rhizobium radiobacter, rhizobium vitis, streptomyces scabies, ralstonia solanacearum, xanthomonas campestris and pectobacterium cartovorum by disc diffusion method. minimum inhibitory concentration and minimum bactericidal concentration were determined by using the serial dilution method. chemical composition of essential ...201525583240
complete genome sequence of biocontrol strain pseudomonas fluorescens lbum223.pseudomonas fluorescens lbum223 is a plant growth-promoting rhizobacterium (pgpr) with biocontrol activity against various plant pathogens. it produces the antimicrobial metabolite phenazine-1-carboxylic acid, which is involved in the biocontrol of streptomyces scabies, the causal agent of common scab of potato. here, we report the complete genome sequence of p. fluorescens lbum223.201525953163
regulation of coronafacoyl phytotoxin production by the pas-luxr family regulator cfar in the common scab pathogen streptomyces scabies.potato common scab is an economically important crop disease that is characterized by the formation of superficial, raised or pitted lesions on the potato tuber surface. the most widely distributed causative agent of the disease is streptomyces scabies, which produces the phytotoxic secondary metabolite thaxtomin a that serves as a key virulence factor for the organism. recently, it was demonstrated that s. scabies can also produce the phytotoxic secondary metabolite coronafacoyl-l-isoleucine (c ...201525826255
the cellobiose sensor cebr is the gatekeeper of streptomyces scabies pathogenicity.a relatively small number of species in the large genus streptomyces are pathogenic; the best characterized of these is streptomyces scabies. the pathogenicity of s. scabies strains is dependent on the production of the nitrated diketopiperazine thaxtomin a, which is a potent plant cellulose synthesis inhibitor. much is known about the genetic loci associated with plant virulence; however, the molecular mechanisms by which s. scabies triggers expression of thaxtomin biosynthetic genes, beyond th ...201525714708
suberin regulates the production of cellulolytic enzymes in streptomyces scabiei, the causal agent of potato common scab.suberin, a major constituent of the potato periderm, is known to promote the production of thaxtomins, the key virulence factors of the common scab-causing agent streptomyces scabiei. in the present study, we speculated that suberin affected the production of glycosyl hydrolases, such as cellulases, by s. scabiei, and demonstrated that suberin promoted glycosyl hydrolase activity when added to cellulose-, xylan-, or lichenin-containing media. furthermore, secretome analyses revealed that the add ...201526330095
comparative secretome analysis of streptomyces scabiei during growth in the presence or absence of potato suberin.suberin is a recalcitrant plant biopolymer composed of a polyphenolic and a polyaliphatic domain. although suberin contributes to a significant portion of soil organic matter, the biological process of suberin degradation is poorly characterized. it has been suggested that streptomyces scabiei, a plant pathogenic bacterium, can produce suberin-degrading enzymes. in this study, a comparative analysis of the s. scabiei secretome from culture media supplemented or not with potato suberin was carrie ...201425028574
thaxtomin a production and virulence are controlled by several bld gene global regulators in streptomyces scabies.streptomyces scabies is the main causative agent of common scab disease, which leads to significant annual losses to potato growers worldwide. the main virulence factor produced by s. scabies is a phytotoxic secondary metabolite called thaxtomin a, which functions as a cellulose synthesis inhibitor. thaxtomin a production is controlled by the cluster-situated regulator txtr, which activates expression of the thaxtomin biosynthetic genes in response to cello-oligosaccharides. here, we demonstrate ...201424678834
long-term induction of defense gene expression in potato by pseudomonas sp. lbum223 and streptomyces scabies.streptomyces scabies is a causal agent of common scab of potato, which generates necrotic tuber lesions. we have previously demonstrated that inoculation of potato plants with phenazine-1-carboxylic acid (pca)- producing pseudomonas sp. lbum223 could significantly reduce common scab symptoms. in the present study, we investigated whether lbum223 or an isogenic phzc- mutant not producing pca could elicit an induced systemic resistance response in potato. the expression of eight defense-related ge ...201424601985
characterization of the integration and modular excision of the integrative conjugative element paist in streptomyces turgidiscabies car8.paist is a large genomic island located in the chromosome of the plant pathogen streptomyces turgidiscabies car8. the island carries clustered virulence genes, transfers to other streptomyces species, and integrates by site-specific recombination at the 8 bp palindrome ttcatgaa. the palindrome is located at the 3' end of the bacitracin resistance gene (baca). we demonstrate that paist is able to excise in modules by recombination of one internal and two flanking palindromic direct repeats. the g ...201424927117
a species-specific method for detecting pathogenic streptomyces species from soil and potato tubers in argentina.potato common scab is caused by several soil-inhabiting pathogenic streptomyces species. in the present study, a species-specific pcr method was used to detect streptomyces species in potato tuber lesions and soils. total genomic dna from soil samples from six locations and tuber samples from four potato cultivars (spunta, shepody, innovator and russet burbank) were assessed. streptomyces scabies, streptomyces acidiscabies, and streptomyces turgidiscabies were detected in soybean, tobacco and po ...201424401784
field efficacy of nonpathogenic streptomyces species against potato common scab.the primary objective of these experiments was to reduce pathogenicity and virulence of endemic soil pathogenic streptomyces strains that cause potato common scab (cs) using nonpathogenic streptomyces strains to suppress cs in a field situation.201424034169
phytotoxins produced by plant pathogenic streptomyces species.streptomyces is a large genus consisting of soil-dwelling, filamentous bacteria that are best known for their capability of producing a vast array of medically and agriculturally useful secondary metabolites. in addition, a small number of streptomyces spp. are capable of colonizing and infecting the underground portions of living plants and causing economically important crop diseases such as potato common scab (cs). research into the mechanisms of streptomyces plant pathogenicity has led to th ...201424131731
the novel grcep12 peptide from the plant-parasitic nematode globodera rostochiensis suppresses flg22-mediated pti.the potato cyst nematode globodera rostochiensis is a biotrophic pathogen that secretes effector proteins into host root cells to promote successful plant parasitism. in addition to the role in generating within root tissue the feeding cells essential for nematode development, (1) nematode secreted effectors are becoming recognized as suppressors of plant immunity. (2)(-) (4) recently we reported that the effector ubiquitin carboxyl extension protein (grubcep12) from g. rostochiensis is processe ...201323803745
the esx/type vii secretion system modulates development, but not virulence, of the plant pathogen streptomyces scabies.streptomyces scabies is a model organism for the investigation of plant-microbe interactions in gram-positive bacteria. here, we investigate the type vii protein secretion system (t7ss) in s. scabies; the t7ss is required for the virulence of other gram-positive bacteria, including mycobacterium tuberculosis and staphylococcus aureus. the hallmarks of a functional t7ss are an eccc protein that forms an essential component of the secretion apparatus and two small, sequence-related substrate prote ...201323009676
detection of potential suberinase-encoding genes in streptomyces scabiei strains and other actinobacteria.streptomyces scabiei causes common scab, an economically important disease of potato tubers. some authors have previously suggested that s. scabiei penetration into host plant tissue is facilitated by secretion of esterase enzymes degrading suberin, a lipidic biopolymer of the potato periderm. in the present study, s. scabiei ef-35 showed high esterase activity in suberin-containing media. this strain also exhibited esterase activity in the presence of other biopolymers, such as lignin, cutin, o ...201323647341
phenazine production by pseudomonas sp. lbum223 contributes to the biological control of potato common scab.common scab of potato is mainly caused by streptomyces scabies. currently, no method can efficiently control this economically important disease. we have previously determined that pseudomonas sp. lbum223 exhibits antagonistic properties toward s. scabies under in vitro conditions. inhibition was mainly attributed to phenazine-1-carboxylic acid (pca) production because an isogenic mutant of lbum223 (phzc-), not producing pca, was incapable of significantly reducing s. scabies growth. in order to ...201323883153
crystal structure of phospholipase a1 from streptomyces albidoflavus na297.the metal-independent lipase from streptomyces albidoflavus na297 (sapla1) is a phospholipase a1 as it preferentially hydrolyzes the sn-1 acyl ester in glycerophospholipids, yielding a fatty acid and 2-acyl-lysophospholipid. the molecular mechanism underlying the substrate binding by sapla1 is currently unknown. in this study, the crystal structure of sapla1 was determined at 1.75å resolutions by molecular replacement. a structural similarity search indicated the highest structural similarity to ...201323416196
solphenazines a-f, glycosylated phenazines from streptomyces sp. strain dl-93.during a survey of actinobacteria known to suppress the growth of streptomyces scabies (the causative agent of potato scab disease) in vivo, six new rhamnosylated alkaloids, the solphenazines a-f (1-6), were isolated from a biological control strain of streptomyces (dl-93). the known rhamnosyl analogue of paraben (9) was also isolated along with a new rhamnosylated derivative of n-methyl-p-aminobenzoic acid (10). none of the compounds exhibited any antibacterial or antifungal activity against a ...201323317013
pathogen variation and urea influence selection and success of streptomyces mixtures in biological control.success in biological control of plant diseases remains inconsistent in the field. a collection of well-characterized streptomyces antagonists (n = 19 isolates) was tested for their capacities to inhibit pathogenic streptomyces scabies (n = 15 isolates). there was significant variation among antagonists in ability to inhibit pathogen isolates and among pathogens in their susceptibility to inhibition. only one antagonist could inhibit all pathogens, and antagonist-pathogen interactions were highl ...201323035630
structure and biosynthesis of scabichelin, a novel tris-hydroxamate siderophore produced by the plant pathogen streptomyces scabies 87.22.scabichelin and turgichelin, novel tris-hydroxamate siderophores, were isolated from streptomyces antibioticus nbrc 13838/streptomyces scabies jcm 7914 and streptomyces turgidiscabies jcm 10429, respectively. the planar structures of scabichelin and turgichelin were elucidated by mass spectrometry, and 1- and 2-d nmr spectroscopic analyses of their gallium(iii) complexes. the relative and absolute stereochemistry of the metabolites was determined by the modified marfey's method in conjunction wi ...201323752895
structural insights into the mechanism for recognizing substrate of the cytochrome p450 enzyme txte.thaxtomins, a family of phytotoxins produced by streptomyces spp., can cause dramatic plant cell hypertrophy and seedling stunting. thaxtomin a is the dominant form from streptomyces scabies and has demonstrated herbicidal action. txte, a cytochrome p450 enzyme from streptomyces scabies 87.22, catalyzes direct nitration of the indolyl moiety of l-tryptophan to l-4-nitrotryptophan using nitric oxide, dioxygen and nadph. the crystal structure of txte was determined at 2.1 å resolution and describe ...201324282603
thaxtomin a-deficient endophytic streptomyces sp. enhances plant disease resistance to pathogenic streptomyces scabies.each plant species in nature harbors endophytes, a community of microbes living within host plants without causing any disease symptom. however, the exploitation of endophyte-based phytoprotectants is hampered by the paucity of mechanistic understandings of endophyte-plant interaction. we here reported two endophytic streptomyces isolates ifb-a02 and ifb-a03 recovered from a stress-tolerant dicotyledonous plant artemisia annua l. after the determination of their non-pathogenicity at the genomic ...201222922880
characterization of streptomyces plasmid-phage pfp4 and its evolutionary implications.autonomous-replicating plasmid pfp4 of streptomyces sp. fr1 isolated from a heavy metal-contaminated land was cloned and sequenced. surprisingly, the 40,949-bp pfp4 contains a cluster of 20 genes, resembling these chromosome-integrated prophages of streptomyces sp. spb78 and streptomyces scabiei 87.22. plasmid pfp4 could transfer by conjugation and a replication locus, iteron/repa/repb, was identified. the filtered fr1 culture could infect both fr1 and fr1 cured of pfp4 to form plaques, and also ...201222677103
high-throughput screening of microbial adaptation to environmental stress.we developed a microwell plate, high-throughput, screening method aimed at quantitating the tolerance of a panel of gram-positive and gram-negative bacteria to metals (frankia sp., escherichia coli, cupriavidus metallidurans, rhizobium leguminosarum, and streptomyces scabies). microbial viability was quantified using mts; a tetrazolium salt converted to a water-soluble formazan through microbial reduction. in this paper, we present the stepwise development of the method, highlighting the main el ...201121315114
dissecting the complete lipoprotein biogenesis pathway in streptomyces scabies.following translocation, bacterial lipoproteins are lipidated by lipoprotein diacylglycerol transferase (lgt) and cleaved of their signal peptides by lipoprotein signal peptidase (lsp). in gram-negative bacteria and mycobacteria, lipoproteins are further lipidated by lipoprotein n-acyl transferase (lnt), to give triacylated lipoproteins. streptomyces are unusual amongst gram-positive bacteria because they export large numbers of lipoproteins via the twin arginine protein transport (tat) pathway. ...201121477129
tryptophan regulates thaxtomin a and indole-3-acetic acid production in streptomyces scabiei and modifies its interactions with radish seedlings.the virulence of streptomyces scabiei, the causal agent of common scab, depends mainly on the production of the toxin thaxtomin a. s. scabiei also produces indole-3-acetic acid (iaa), but the role of this hormone in the interaction between pathogenic streptomycetes and plants has not yet been elucidated. tryptophan is a biosynthetic precursor of both iaa and thaxtomin a. in this study, the effect of tryptophan on thaxtomin a and iaa production as well as its effect on the transcription of the co ...201121521002
genome shuffling enhances biocontrol abilities of streptomyces strains against two potato pathogens.aims:ôçé to employ the genome shuffling technique for improving the phenotype of a biocontrol control agent of the genus streptomyces. methods and results:ôçé two rounds of genome shuffling (gs) were carried out with streptomyces melanosporofaciens ef-76, a geldanamycin producer. six fusants that showed optimized in vitro antagonistic activity against streptomyces scabies or phytophthora infestans, two important pathogens of potato crops, were selected. all selected fusants retained the capacity ...201121672101
the plant pathogen streptomyces scabies 87-22 has a functional pyochelin biosynthetic pathway that is regulated by tetr- and afsr-family proteins.siderophores are high-affinity iron-chelating compounds produced by bacteria for iron uptake that can act as important virulence determinants for both plant and animal pathogens. genome sequencing of the plant pathogen, streptomyces scabies 87-22, revealed the presence of a putative pyochelin biosynthetic gene cluster (pbgc). liquid chromatography-mass spectrometry (lc-ms) analyses of culture supernatants of s. scabies mutants in which expression of the cluster is upregulated and which lack a ke ...201121757492
potato suberin induces differentiation and secondary metabolism in the genus streptomyces.bacteria of the genus streptomyces are soil microorganisms with a saprophytic life cycle. previous studies have revealed that the phytopathogenic agent s. scabiei undergoes metabolic and morphological modifications in the presence of suberin, a complex plant polymer. this paper investigates morphological changes induced by the presence of potato suberin in five species of the genus streptomyces, with emphasis on s. scabiei. streptomyces scabiei, s. acidiscabies, s. avermitilis, s. coelicolor and ...201122129602
stacking of antimicrobial genes in potato transgenic plants confers increased resistance to bacterial and fungal pathogens.solanum tuberosum plants were transformed with three genetic constructions expressing the nicotiana tabacum ap24 osmotine, phyllomedusa sauvagii dermaseptin and gallus gallus lysozyme, and with a double-transgene construction expressing the ap24 and lysozyme sequences. re-transformation of dermaseptin-transformed plants with the ap24/lysozyme construction allowed selection of plants simultaneously expressing the three transgenes. potato lines expressing individual transgenes or double- and tripl ...201122115953
involvement of the plant polymer suberin and the disaccharide cellobiose in triggering thaxtomin a biosynthesis, a phytotoxin produced by the pathogenic agent streptomyces scabies.streptomyces scabies is a gram-positive soil bacterium recognized as the main causal agent of common scab. pathogenicity in streptomyces spp. depends on their capacity to synthesize phytotoxins called thaxtomins. genes involved in biosynthesis of these secondary metabolites are known to be induced by cellobiose, a plant disaccharide. however, growth of s. scabies in a minimal medium containing cellobiose as a carbon source is very poor and only generates traces of thaxtomins. the effect of suber ...201019968554
rapid and specific method for evaluating streptomyces competitive dynamics in complex soil communities.quantifying target microbial populations in complex communities remains a barrier to studying species interactions in soil environments. quantitative pcr (qpcr) assays were developed for quantifying pathogenic streptomyces scabiei and antibiotic-producing streptomyces lavendulae strains in complex soil communities. this assay will be useful for evaluating the competitive dynamics of streptomycetes in soil.201020080993
biodegradation of 5-nitroanthranilic acid by bradyrhizobium sp. strain js329.biodegradation of synthetic compounds has been studied extensively, but the metabolic diversity required for catabolism of many natural compounds has not been addressed. 5-nitroanthranilic acid (5naa), produced in soil by streptomyces scabies, is also the starting material for synthetic dyes and other nitroaromatic compounds. bradyrhizobium js329 was isolated from soil by selective enrichment with 5naa. when grown on 5naa, the isolate released stoichiometric amounts of nitrite and half of the st ...201020081004
what does it take to be a plant pathogen: genomic insights from streptomyces species.plant pathogenicity is rare in the genus streptomyces, with only a dozen or so species possessing this trait out of the more than 900 species described. nevertheless, such species have had a significant impact on agricultural economies throughout the world due to their ability to cause important crop diseases such as potato common scab, which is characterized by lesions that form on the potato tuber surface. all pathogenic species that cause common scab produce a family of phytotoxins called the ...201020396949
the twin arginine protein transport pathway exports multiple virulence proteins in the plant pathogen streptomyces scabies.summary streptomyces scabies is one of a group of organisms that causes the economically important disease potato scab. analysis of the s. scabies genome sequence indicates that it is likely to secrete many proteins via the twin arginine protein transport (tat) pathway, including several proteins whose coding sequences may have been acquired through horizontal gene transfer and share a common ancestor with proteins in other plant pathogens. inactivation of the s. scabies tat pathway resulted in ...201020487278
isolation and characterization of antagonistic fungi against potato scab pathogens from potato field soils.potato scab is a serious plant disease caused by several streptomyces sp., and effective control methods remain unavailable. although antagonistic bacteria and phages against potato scab pathogens have been reported, to the best of our knowledge, there is no information about fungi that are antagonistic to the pathogens. the aim of this study was to isolate fungal antagonists, characterize their phylogenetic positions, determine their antagonistic activities against potato scab pathogens, and hi ...201020653777
the ability of pseudomonas sp. lbum 223 to produce phenazine-1-carboxylic acid affects the growth of streptomyces scabies, the expression of thaxtomin biosynthesis genes and the biological control potential against common scab of potato.streptomyces scabies causes common scab, an economical disease affecting potato crops world-wide, for which no effective control measure exists. this pathogen produces the plant toxin thaxtomin a, which is involved in symptom development on potato tubers. a biological control approach that can limit s. scabies growth and repress thaxtomin production represents an attractive alternative to classical control strategies. pseudomonas sp. lbum 223 produces phenazine-1-carboxylic acid (pca), an antibi ...201021073487
multilocus sequence analysis of phytopathogenic streptomyces species.the identification and classification of species within the genus streptomyces is difficult because there are presently 576 species with validly published names and this number increases every year. the value of the application of multilocus sequence analysis scheme to the systematics of streptomyces species has been well demonstrated in several recently published papers. in this study the sequence fragments of 4 housekeeping genes, atpd, reca, rpob, and trpb, were determined for the type strain ...201021112986
habituation to thaxtomin a in hybrid poplar cell suspensions provides enhanced and durable resistance to inhibitors of cellulose synthesis.thaxtomin a (ta), a phytotoxin produced by the phytopathogen streptomyces scabies, is essential for the development of potato common scab disease. ta inhibits cellulose synthesis but its actual mode of action is unknown. addition of ta to hybrid poplar (populus trichocarpa x populus deltoides) cell suspensions can activate a cellular program leading to cell death. in contrast, it is possible to habituate hybrid poplar cell cultures to grow in the presence of ta levels that would normally induce ...201021143977
streptomyces scabies 87-22 contains a coronafacic acid-like biosynthetic cluster that contributes to plant-microbe interactions.plant-pathogenic streptomyces spp. cause scab disease on economically important root and tuber crops, the most important of which is potato. key virulence determinants produced by these species include the cellulose synthesis inhibitor, thaxtomin a, and the secreted nec1 protein that is required for colonization of the plant host. recently, the genome sequence of streptomyces scabies 87-22 was completed, and a biosynthetic cluster was identified that is predicted to synthesize a novel compound s ...201020064060
streptomyces turgidiscabies car8 contains a modular pathogenicity island that shares virulence genes with other actinobacterial plant pathogens.streptomyces turgidiscabies car8 is an actinobacterium that causes the economically important disease potato scab. pathogenesis in this species is associated with a mobile pathogenicity island (paist) that site specifically inserts into the baca gene in streptomyces spp. here we provide the 674,223 bp sequence of paist, which consists of two non-overlapping modules of 105,364 and 568,859 bp. these modules are delimited by three copies of an 8 bp palindromic sequence (ttcatgaa), that also is the ...201021087627
hopanoids are not essential for growth of streptomyces scabies 87-22.hopanoids are triterpenoic, pentacyclic compounds that are structurally similar to sterols, which are required for normal cell function in eukaryotes. hopanoids are thought to be an important component of bacterial cell membranes because they control membrane fluidity and diminish passive diffusion of ions, and a few taxons modulate their hopanoid content in response to environmental stimuli. however, to our knowledge, mutational studies to assess the importance of hopanoids in bacterial physiol ...200919502399
two different signaling pathways for thaxtomin a-induced cell death in arabidopsis and tobacco by2.thaxtomin a (txt) is a phytotoxin produced by all plant-pathogenic streptomyces scabies involved in the potato scab disease. their pathogenicity was previously correlated with the production of txt. calcium is known to be an essential second messenger associated with pathogen-induced plant responses and cell death. we have effectively shown that in arabidopsis thaliana cell suspensions, txt induces an early short lived ca(2+) influx which is involved in the cell death process and other txt-induc ...200919649193
genetic and physiological determinants of streptomyces scabies pathogenicity.summary common scab is a severe disease worldwide affecting tap root crops and potato tubers. it is caused by soil-borne filamentous bacteria belonging to the genus streptomyces. streptomycetes usually are saprophytic microorganisms, but a few species have acquired the ability to infect underground plant tissues. the predominant causal agent of potato scab worldwide is streptomyces scabies. the production of phytotoxins called thaxtomins is essential for the virulence of common scab-causing agen ...200919694949
streptomyces scabiei and its toxin thaxtomin a induce scopoletin biosynthesis in tobacco and arabidopsis thaliana.streptomyces scabiei is the predominant causal agent of common scab of potato in north america. the virulence of common scab-causing streptomycetes relies on their capacity to synthesize thaxtomins. in this study, the effects of s. scabiei infection and of thaxtomin a, the main toxin produced by s. scabiei, were tested for the elicitation of plant defense molecules in the model plants tobacco (nicotiana tabacum) and arabidopsis thaliana. tobacco leaves infected with spores of s. scabiei strain e ...200919859716
yest: a new rhamnogalacturonan acetyl esterase from bacillus subtilis.yest, a putative protein from bacillus subtilis atcc 6633 that has been provisionally classified as a rhamnogalacturonan acetyl esterase (rgae) in ce-12 family, was cloned, expressed in escherichiacoli rosetta (de3), and purified. the enzyme is monomeric with a molecular mass of 37 kda and presents thermophilic properties similar to rgae from aspergillus aculeatus, although yest is more alkaliphilic. the study of inhibitors confirmed the importance of the his and the nucleophilic ser for the est ...200817957779
thaxtomin biosynthesis: the path to plant pathogenicity in the genus streptomyces.streptomyces species are best known for their ability to produce a wide array of medically and agriculturally important secondary metabolites. however, there is a growing number of species which, like streptomyces scabies, can function as plant pathogens and cause scab disease on economically important crops such as potato. all of these species produce the phytotoxin thaxtomin, a nitrated dipeptide which inhibits cellulose synthesis in expanding plant tissue. the biosynthesis of thaxtomin involv ...200818392685
streptomyces deccanensis sp. nov., an alkaliphilic species isolated from soil.a novel actinomycete strain, das-139t, was isolated from a soil sample collected from gulbarga, karnataka province, india. the isolate was characterized by white to grey aerial mycelium. long spore chains were found on the aerial mycelium and the aerial mycelium was composed of non-motile spores with hairy surfaces. the cell wall of strain das-139t contained ll-diaminopimelic acid isomer as the diagnostic diaminoacid indicating that the cell wall was of chemotype-i. the predominant menaquinones ...200818450694
identification and functional analysis of genes controlling biosynthesis of 2-methylisoborneol.to identify the genes for biosynthesis of the off-flavor terpenoid alcohol, 2-methylisoborneol (2-mib), the key genes encoding monoterpene cyclase were located in bacterial genome databases by using a combination of hidden markov models, protein-family search, and the sequence alignment of their gene products. predicted terpene cyclases were classified into three groups: sesquiterpene, diterpene, and other terpene cyclases. genes of the terpene cyclase group that form an operon with a gene encod ...200818492804
genetic diversity of streptomyces spp. causing common scab of potato in eastern canada.common scab is an important disease of potato caused by streptomyces scabies and other closely related species. in this study, the genetic diversity of streptomyces spp. causing common scab of potato in eastern canada was for the first time investigated. forty-one streptomyces spp. isolates were retrieved from necrotic lesions of potato tubers harvested from different regions of the canadian provinces new-brunswick, nova scotia and prince-edward-island. most isolates were closely related to know ...200818947953
an early ca2+ influx is a prerequisite to thaxtomin a-induced cell death in arabidopsis thaliana cells.the pathogenicity of various streptomyces scabies isolates involved in potato scab disease was correlated with the production of thaxtomin a. since calcium is known as an essential second messenger associated with pathogen-induced plant responses and cell death, it was investigated whether thaxtomin a could induce a ca2+ influx related to cell death and to other putative plant responses using arabidopsis thaliana suspension cells, which is a convenient model to study plant-microbe interactions. ...200819015217
distinguishing bacterial pathogens of potato using a genome-wide microarray approach.a set of 9676 probes was designed for the most harmful bacterial pathogens of potato and tested in a microarray format. gene-specific probes could be designed for all genes of pectobacterium atrosepticum, c. 50% of the genes of streptomyces scabies and c. 30% of the genes of clavibacter michiganensis ssp. sepedonicus utilizing the whole-genome sequence information available. for streptomyces turgidiscabies, 226 probes were designed according to the sequences of a pathogenicity island containing ...200819018999
disruption of sscr encoding a gamma-butyrolactone autoregulator receptor in streptomyces scabies nbrc 12914 affects production of secondary metabolites.we report the cloning and sequence analysis of a gamma-butyrolactone autoregulator regulatory island that includes an sscr gene encoding the gamma-butyrolactone autoregulator receptor from streptomyces scabies nbrc 12914, a plant pathogenic strain. gamma-butyrolactone autoregulators trigger secondary metabolism, and sometimes morphological differentiation in the gram-positive genus streptomyces through binding to a specific autoregulator receptor. this gene cluster showed close similarity to oth ...200818500630
against conservation of specific epithets formed wrongly as nominative nouns in apposition.together with 31 other incorrectly formed (i.e. as nominative nouns in apposition) specific epithets, the epithet of streptomyces scabies was corrected to streptomyces scabiei in taxonomic notes published in 1997 and 1998. a subsequent request for an opinion, published in 2001, to reinstate the incorrect epithets for ten of these species was denied by the judicial commission in 2002. in 2007, a further request for an opinion was submitted to the judicial commission which proposed the conservatio ...200818523205
development of a genotyping method for potato scab pathogens based on multiplex pcr.scab disease significantly damages potato and other root crops. streptomyces scabiei, s. acidiscabiei, and s. turgidiscabiei are the best-known causal agents of this disease. we have developed a novel genotyping method for these potato scab pathogens using multiplex pcr, whose benefits include rapid and easy detection of multiple species. we designed a species-specific primer set (6 primers, 3 pairs) for the 16s rrna genes and 16s-23s its regions of these potato scab pathogens. the specificity o ...200818776692
streptomyces scabies 87-22 possesses a functional tomatinase.the actinomycete streptomyces scabies 87-22 is the causal agent of common scab, an economically important disease of potato and taproot crops. sequencing of the s. scabies 87-22 genome revealed the presence of a gene with high homology to the gene encoding the alpha-tomatine-detoxifying enzyme tomatinase found in fungal tomato pathogens. the toma gene from s. scabies 87-22 was cotranscribed with a putative family 1 glycosyl hydrolase gene, and purified toma protein was active only on alpha-tomat ...200818835993
synthesis and uptake of the compatible solutes ectoine and 5-hydroxyectoine by streptomyces coelicolor a3(2) in response to salt and heat stresses.streptomyces coelicolor a3(2) synthesizes ectoine and 5-hydroxyectoine upon the imposition of either salt (0.5 m nacl) or heat stress (39 degrees c). the cells produced the highest cellular levels of these compatible solutes when both stress conditions were simultaneously imposed. protection against either severe salt (1.2 m nacl) or heat stress (39 degrees c) or a combination of both environmental cues could be accomplished by adding low concentrations (1 mm) of either ectoine or 5-hydroxyectoi ...200818849444
assessment of common scab-inducing pathogen effects on potato underground organs via computed tomography scanning.common scab caused by streptomyces scabies is a major bacterial disease of potato (solanum tuberosum). its best known symptom is superficial lesions on the surface of progeny potato tubers, observed at harvesting. in this study, effects of s. scabies on space occupancy by underground organs and on structural complexity of root systems are investigated during growth via computed tomography (ct) scanning. two groups of potato plants were grown in a greenhouse in middle-sized plastic pots. using a ...200818943458
antimycin a-producing nonphytopathogenic streptomyces turgidiscabies from potato.to detect if substances with mammalian cell toxicity are produced by streptomyces turgidiscabies and streptomyces scabiei isolated from potato scab lesions.200818070040
effect of potato suberin on streptomyces scabies proteome.two-dimensional (2d) page was used to detect proteins induced in streptomyces scabies by potato suberin, a lipidic plant polymer. nineteen up-regulated proteins were excised from 2d gels and analysed by n-terminal sequencing or tandem mass spectrometry (ms/ms). four of the up-regulated proteins could be linked to the bacterial response to stress (aldh, groes, terd and lexa). specific metabolic pathways seemed to be activated in the presence of suberin, as shown by the increased expression of spe ...200819019004
edaphic soil levels of mineral nutrients, ph, organic matter, and cationic exchange capacity in the geocaulosphere associated with potato common scab.abstract in order to determine possible relationships between geocaulosphere soil properties and severity of common scab of potato caused by streptomyces scabies, soils were collected from representative commercial potato fields in canada: in simcoe and dufferin counties, ontario and across prince edward island (pei) in august 2004. soils immediately adjacent to tubers were sampled and analyzed for select edaphic factors and for pathogen presence using polymerase chain reaction (pcr) tests with ...200718944172
recommendation for the conservation of the name streptomyces scabies. request for an opinion.the primary streptomycete inciting common scab of potato was first legitimately described by thaxter in 1892 as 'oospora scabies', preserving the spelling of an epithet in use since 1846. the name streptomyces scabies, dating to 1948, was revived in 1989, but changed to streptomyces scabiei in 1997 to follow grammatical convention. considering the long-established use and general recognition of 'scabies', it is proposed that the original epithet be conserved.200717911322
the arac/xyls regulator txtr modulates thaxtomin biosynthesis and virulence in streptomyces scabies.streptomyces scabies is the best studied of those streptomycetes that cause an economically important disease known as potato scab. the phytotoxin thaxtomin is made exclusively by these pathogens and is required for virulence. here we describe regulation of thaxtomin biosynthesis by txtr, a member of the arac/xyls family of transcriptional regulators. the txtr gene is imbedded in the thaxtomin biosynthetic pathway and is located on a conserved pathogenicity island in s. scabies, s. turgidiscabie ...200717919290
a novel teichoic acid from the cell wall of streptomyces sp. vkm ac-2275.the cell wall of a pathogenic strain streptomyces sp. vkm ac-2275 isolated from potato tubers infected by scab contains a teichoic acid related to poly(glycosylpolyol phosphate) with a repeating unit established by chemical and nmr spectroscopic methods. about 60% of l-rhamnose residues bear an o-acetyl group at o-2 and 20% of the internal glucose residues contain an additional phosphate at c-4. the polymer is built of 5-6 units. this structure is found in bacteria for the first time. the strain ...200716949058
detection of the nec1 virulence gene and its correlation with pathogenicity in streptomyces species on potato tubers and in soil using conventional and real-time pcr.to evaluate the virulence gene nec1 as a reliable marker for the detection of pathogenic streptomyces species on potato tubers and in soil samples using conventional and real-time quantitative pcr assays.200717381752
effect of acidic electrolyzed water on the viability of bacterial and fungal plant pathogens and on bacterial spot disease of tomato.acidic electrolyzed water (aew), known to have germicidal activity, was obtained after electrolysis of 0.045% aqueous solution of sodium chloride. freshly prepared aew (ph 2.3-2.6, oxidation-reduction potential 1007-1025 mv, and free active chlorine concentration 27-35 ppm) was tested in vitro and (or) on tomato foliage and seed surfaces for its effects on the viability of plant pathogen propagules that could be potential seed contaminants. foliar sprays of aew were tested against bacterial spot ...200617110959
streptomyces turgidiscabies and streptomyces reticuliscabiei: one genomic species, two pathogenic groups.three strains of streptomyces reticuliscabiei and two strains of streptomyces turgidiscabies were analysed, together with reference and type strains of other streptomyces species, for phenotypic traits, dna-dna relatedness, comparison of 16s rrna gene sequences and presence of necrotic protein gene (nec1) homologues in order to clarify their phylogenetic relationships. a numerical analysis of phenotypic characteristics showed that s. reticuliscabiei and s. turgidiscabies belong to the same clust ...200617158976
evolution of plant pathogenicity in streptomyces.among the multitude of soil-inhabiting, saprophytic streptomyces species are a growing number of plant pathogens that cause economically important diseases, including potato scab. streptomyces scabies is the dominant pathogenic species worldwide, but is only one of many that cause very similar disease symptoms on plants. molecular genetic analysis is beginning to identify the mechanisms used by plant pathogenic species to manipulate their hosts. the nitrated dipeptide phytotoxin, thaxtomin, inhi ...200616719719
biological control agent of common scab disease by antagonistic strain bacillus sp. sunhua.to identify an antagonistic strain against streptomyces scabiei and to characterize the antibiotic agent. the efficacy of the isolated strain in controlling common scab disease was also evaluated.200515960681
a large, mobile pathogenicity island confers plant pathogenicity on streptomyces species.potato scab is a globally important disease caused by polyphyletic plant pathogenic streptomyces species. streptomyces acidiscabies, streptomyces scabies and streptomyces turgidiscabies possess a conserved biosynthetic pathway for the nitrated dipeptide phytotoxin thaxtomin. these pathogens also possess the nec1 gene which encodes a necrogenic protein that is an independent virulence factor. in this article we describe a large (325-660 kb) pathogenicity island (pai) conserved among these three p ...200515686551
rare trisubstituted sesquiterpenes daucanes from the wild daucus carota.phytochemical and biological investigation of the roots of the wild daucus carota ssp. carota afforded three new and four known compounds, including four sesquiterpenes daucane esters (1-3 [new], and 4), one polyacetylene (5), one sesquiterpene coumarin (6), and sitosterol glucoside. the structures of the new compounds were determined by comprehensive nmr studies, including dept, cosy, noesy, hmqc and hmbc analyses. based on an agar diffusion assay, 1, 2 and 4-6 were screened and found to contai ...200515964039
variation in antibiosis ability, against potato pathogens, of bacterial communities recovered from the endo- and exoroots of potato crops produced under conventional versus minimum tillage systems.the culturable component of bacterial communities found in the endoroot and associated exoroot (root zone soil) was examined in potatoes (solanum tuberosum l.) grown under either conventional or minimum tillage systems. bacterial species--abundance relationships were determined and in vitro antibiosis ability investigated to discover whether tillage practice or bacteria source (endo- or exoroot) influenced bacterial community structure and functional versatility. antibiosis abilities against phy ...200516234863
thaxtomin a induces programmed cell death in arabidopsis thaliana suspension-cultured cells.thaxtomin a is the main phytotoxin produced by streptomyces scabiei, the causative agent of common scab disease of potato. pathogenicity of s. scabiei is dependent on the production of thaxtomin a which is required for the development of disease symptoms, such as growth inhibition and cell death. we investigated whether thaxtomin a-induced cell death was similar to the hypersensitive cell death that often occurs in response to specific pathogens or phytotoxins during the so-called hypersensitive ...200516025344
phylogenetic analysis of streptomyces spp. isolated from potato scab lesions in korea on the basis of 16s rrna gene and 16s-23s rdna internally transcribed spacer sequences.the 16s rrna gene sequences for 34 strains, including 11 isolates, were determined to classify scab-causing streptomyces spp. and relatives isolated from potato scab lesions collected in jeju, korea. the 16s-23s rdna internally transcribed spacer (its) sequences were determined to investigate whether the 16s-23s its region is useful for analysing intra- and interspecific relationships in these bacteria. on the basis of phylogenetic analysis of 16s rrna gene sequences, most of the isolates were c ...200414742481
biotransformation of the streptomyces scabies phytotoxin thaxtomin a by the fungus aspergillus niger.of several hundred microorganisms randomly selected from the environment, only a fungal isolate identified as aspergillus niger van tiegham var. niger was found to transform the phytotoxin thaxtomin a to much less toxic metabolites. the rate and extent of transformation of thaxtomin a was tested under a variety of conditions, including different growth media, biomass concentrations, incubation periods, and shaker speeds. under optimum conditions the fungus converted thaxtomin a into two major an ...200415052314
endophytic bacterial communities of field-grown potato plants and their plant-growth-promoting and antagonistic abilities.to study the effect of plant growth on potato-associated bacteria, the composition and properties of bacteria colonizing the endosphere of field-grown potato were analyzed by a multiphasic approach. the occurrence and diversity of potato-associated bacteria were monitored by a cultivation-independent approach, using terminal restriction fragment length polymorphism analysis of 16s rdna. the patterns obtained revealed a high heterogeneity of community composition and suggested the existence of pl ...200415213748
characterization of streptomyces scabies mutants deficient in melanin biosynthesis.streptomyces scabies, a causal agent of common scab, produces both melanin and a secondary metabolite called thaxtomin a. to establish a possible relation between melanin and thaxtomin a production in s. scabies, we carried out n-methyl-n'-nitro-n-nitrosoguanidine (ntg) mutagenesis and isolated 11 melanin-negative mutants of s. scabies ef-35. these mutants were characterized for thaxtomin a production, pathogenicity, sporulation, and stress resistance. nine of these mutants showed a significant ...200415644924
isolation and characterisation of antibiotic producing microorganisms in composted nigerian soil.compost samples obtained from different locations within the premises of the university of lagos were analysed to determine the presence and types of antibiotic-producing bacteria, fungi and actinomycetes using nutrient agar, potato dextrose agar and starch casein nitrate agar respectively as culture media. a variety of bacteria were isolated and these included staphylococcus aureus, b. subtilis, b. pumilis, b. lactesporus, b. megaterium, b. pulvifaciens, b. licheniformis, streptococus spp., cor ...200415847340
antagonistic properties of two recombinant strains of streptomyces melanosporofaciens obtained by intraspecific protoplast fusion.intraspecific protoplast fusion was used to produce stable prototrophic recombinants of streptomyces melanosporofaciens ef-76, a biocontrol agent of plant disease producing geldanamycin. two recombinant strains (fp-54 and fp-60) that differed with regard to their antagonistic properties against bacillus cereus atcc 14579, streptomyces scabies ef-35 and phytophthora fragariae var. rubi 390 were characterized. fp-60 lost the ability to inhibit the in vitro growth of these microbial strains while f ...200312883869
an arabidopsis mutant resistant to thaxtomin a, a cellulose synthesis inhibitor from streptomyces species.thaxtomin a is a phytotoxin produced by streptomyces scabies and other streptomyces species, the causative agents of common scab disease in potato and other taproot crops. at nanomolar concentrations, thaxtomin causes dramatic cell swelling, reduced seedling growth, and inhibition of cellulose synthesis in arabidopsis. we identified a mutant of arabidopsis, designated txr1, that exhibits increased resistance to thaxtomin as a result of a decrease in the rate of toxin uptake. the txr1 gene was id ...200312897252
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