Classification of 'Streptomyces hyalinum' Hamada and Yokoyama as Embleya hyalina sp. nov., the second species in the genus Embleya, and emendation of the genus Embleya.

The 16S rRNA gene sequence of 'Streptomyces hyalinum' NBRC 13850T shows 99.7 % similarity to that of Embleya scabrispora DSM 41855T; however, it shows <96.1 % similarity to any other type strains, including Streptomyces spp. Phylogenetic analysis based on 16S rRNA gene sequences clearly suggests that 'S. hyalinum' belongs to the genus Embleya rather than to Streptomyces. The strain possesses ll-diaminopimelic acid in the cell wall. The major menaquinone observed is MK-9(H6), and MK-9(H4) and MK-9(H8) are minor components. The major polar lipids are diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. In this study, the whole genome of strain NBRC 13850T was sequenced, and digital DNA-DNA hybridisation between 'S. hyalinum' NBRC 13850T and E. scabrispora DSM 41855T demonstrated 31.2 % of relatedness value between the two genomes. Morphological, chemotaxonomic, biochemical and physiological data also revealed that 'S. hyalinum' can be easily differentiated from E. scabrispora (the only the valid species of the genus Embleya) and that it merits separate species status. This phenotypic and genetic evidence reveals that 'S. hyalinum' represents a novel species of the genus Embleya; the name Embleya hyalina sp. nov. is proposed for this species. The type strain is NBRC 13850T (=ATCC 29817T=MB 891-A1T). We also emended the description of the genus Embleya considering the feature of E. hyalina.

Genome analysis-based reclassification of Streptomyces endus and Streptomyces sporocinereus as later heterotypic synonyms of Streptomyces hygroscopicus subsp. hygroscopicus.

The aim of this study was to reclarify the taxonomic relationship among Streptomyces hygroscopicus subsp. hygroscopicus, Streptomyces endus and Streptomyces sporocinereus. Whole genome shotgun sequencing was performed for the type strains of these three taxa. Average nucleotide identity and digital DNA-DNA hybridization values among the three taxa were greater than the thresholds for bacterial species delineation, indicating that they belong to the same genomospecies. In addition, the phenotypic data previously reported also support the synonymy. Therefore, S. endus and S. sporocinereus should be reclassified as later heterotypic synonyms of S. hygroscopicus subsp. hygroscopicus.

Identification of the Three Genes Involved in Controlling Production of a Phytotoxin Tropolone in Burkholderia plantarii.

UNLABELLED: Tropolone, a phytotoxin produced by Burkholderia plantarii, causes rice seedling blight. To identify genes involved in tropolone synthesis, we systematically constructed mutations in the genes encoding 55 histidine kinases and 72 response regulators. From the resulting defective strains, we isolated three mutants, KE1, KE2, and KE3, in which tropolone production was repressed. The deleted genes of these mutants were named troR1, troK, and troR2, respectively. The mutant strains did not cause rice seedling blight, and complementation experiments indicated that TroR1, TroK, and TroR2 were involved in the synthesis of tropolone in B. plantarii However, tropolone synthesis was repressed in the TroR1 D52A, TroK H253A, and TroR2 D46A site-directed mutants. These results suggest that the putative sensor kinase (TroK) and two response regulators (TroR1 and TroR2) control the production of tropolone in B. plantarii IMPORTANCE: A two-component system is normally composed of a sensor histidine kinase (HK) and a cognate response regulator (RR) pair. In this study, HK (TroK) and two RRs (TroR1 and TroR2) were found to be involved in controlling tropolone production in B. plantarii These three genes may be part of a bacterial signal transduction network. Such networks are thought to exist in other bacteria to regulate phytotoxin production, as well as environmental adaptation and signal transduction.

Proposal of nine novel species of the genus Lysinimicrobium and emended description of the genus Lysinimicrobium.

Thirteen novel Gram-stain-positive bacteria were isolated from various samples collected from mangrove forests in Japan, and their taxonomic positions were investigated by a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequence comparisons showed that the 13 isolates formed a single clade with Lysinimicrobium mangrovi HI08-69T, with a similarity range of 97.6-99.5 %. The peptidoglycan of the isolates was of the A4α type with an interpeptide bridge comprising Ser-Glu and an l-Ser residue at position 1 of the peptide subunit. The predominant menaquinone was demethylmenaquinone DMK-9(H4) and the major fatty acid was anteiso-C15 : 0. These chemotaxonomic characteristics corresponded to those of the genus Lysinimicrobium. On the basis of the phenotypic and phylogenetic data, along with average nucleotide identity values among the isolates, we concluded that the 13 isolates should be assigned to the following nine novel species of the genus Lysinimicrobium: Lysinimicrobium aestuarii sp. nov. (type strain HI12-104T = NBRC 109392T = DSM 28144T), Lysinimicrobium flavum sp. nov. (type strain HI12-45T = NBRC 109391T = DSM 28150T), Lysinimicrobium gelatinilyticum sp. nov. (type strain HI12-44T = NBRC 109390T = DSM 28149T), Lysinimicrobium iriomotense sp. nov. (type strain HI12-143T = NBRC 109399T = DSM 28146T), Lysinimicrobium luteum sp. nov. (type strain HI12-123T = NBRC 109395T = DSM 28147T), Lysinimicrobium pelophilum sp. nov. (type strain HI12-111T = NBRC 109393T = DSM 28148T), Lysinimicrobium rhizosphaerae sp. nov. (type strain HI12-135T = NBRC 109397T = DSM 28152T), Lysinimicrobium soli sp. nov. (type strain HI12-122T = NBRC 109394T = DSM 28151T) and Lysinimicrobium subtropicum sp. nov. (type strain HI12-128T = NBRC 109396T = DSM 28145T). In addition, an emended description of the genus Lysinimicrobium is proposed.

DoBISCUIT: a database of secondary metabolite biosynthetic gene clusters.

This article introduces DoBISCUIT (Database of BIoSynthesis clusters CUrated and InTegrated, http://www.bio.nite.go.jp/pks/), a literature-based, manually curated database of gene clusters for secondary metabolite biosynthesis. Bacterial secondary metabolites often show pharmacologically important activities and can serve as lead compounds and/or candidates for drug development. Biosynthesis of each secondary metabolite is catalyzed by a number of enzymes, usually encoded by a gene cluster. Although many scientific papers describe such gene clusters, the gene information is not always described in a comprehensive manner and the related information is rarely integrated. DoBISCUIT integrates the latest literature information and provides standardized gene/module/domain descriptions related to the gene clusters.

Biosynthesis of akaeolide and lorneic acids and annotation of type I polyketide synthase gene clusters in the genome of Streptomyces sp. NPS554.

The incorporation pattern of biosynthetic precursors into two structurally unique polyketides, akaeolide and lorneic acid A, was elucidated by feeding experiments with 13C-labeled precursors. In addition, the draft genome sequence of the producer, Streptomyces sp. NPS554, was performed and the biosynthetic gene clusters for these polyketides were identified. The putative gene clusters contain all the polyketide synthase (PKS) domains necessary for assembly of the carbon skeletons. Combined with the 13C-labeling results, gene function prediction enabled us to propose biosynthetic pathways involving unusual carbon-carbon bond formation reactions. Genome analysis also indicated the presence of at least ten orphan type I PKS gene clusters that might be responsible for the production of new polyketides.

Genome based analysis of type-I polyketide synthase and nonribosomal peptide synthetase gene clusters in seven strains of five representative Nocardia species.

BACKGROUND: Actinobacteria of the genus Nocardia usually live in soil or water and play saprophytic roles, but they also opportunistically infect the respiratory system, skin, and other organs of humans and animals. Primarily because of the clinical importance of the strains, some Nocardia genomes have been sequenced, and genome sequences have accumulated. Genome sizes of Nocardia strains are similar to those of Streptomyces strains, the producers of most antibiotics. In the present work, we compared secondary metabolite biosynthesis gene clusters of type-I polyketide synthase (PKS-I) and nonribosomal peptide synthetase (NRPS) among genomes of representative Nocardia species/strains based on domain organization and amino acid sequence homology. RESULTS: Draft genome sequences of Nocardia asteroides NBRC 15531(T), Nocardia otitidiscaviarum IFM 11049, Nocardia brasiliensis NBRC 14402(T), and N. brasiliensis IFM 10847 were read and compared with published complete genome sequences of Nocardia farcinica IFM 10152, Nocardia cyriacigeorgica GUH-2, and N. brasiliensis HUJEG-1. Genome sizes are as follows: N. farcinica, 6.0 Mb; N. cyriacigeorgica, 6.2 Mb; N. asteroides, 7.0 Mb; N. otitidiscaviarum, 7.8 Mb; and N. brasiliensis, 8.9 - 9.4 Mb. Predicted numbers of PKS-I, NRPS, and PKS-I/NRPS hybrid clusters ranged between 4-11, 7-13, and 1-6, respectively, depending on strains, and tended to increase with increasing genome size. Domain and module structures of representative or unique clusters are discussed in the text. CONCLUSION: We conclude the following: 1) genomes of Nocardia strains carry as many PKS-I and NRPS gene clusters as those of Streptomyces strains, 2) the number of PKS-I and NRPS gene clusters in Nocardia strains varies substantially depending on species, and N. brasiliensis strains carry the largest numbers of clusters among the species studied, 3) the seven Nocardia strains studied in the present work have seven common PKS-I and/or NRPS clusters, some of whose products are yet to be studied, and 4) different N. brasiliensis strains have some different gene clusters of PKS-I/NRPS, although the rest of the clusters are common within the N. brasiliensis strains. Genome sequencing suggested that Nocardia strains are highly promising resources in the search of novel secondary metabolites.

Ilumatobacter nonamiense sp. nov. and Ilumatobacter coccineum sp. nov., isolated from seashore sand.

Bacterial strains YM16-303(T) and YM16-304(T) were isolated from a sample of seashore sand using a medium with an artificial seawater base. Both isolates grew slowly on marine agar, and were found to be Gram-reaction-positive, aerobic, non-motile and rod-shaped. The cell-wall peptidoglycan contained ll-diaminopimelic acid, glycine, alanine and hydroxyglutamic acid, and the acyl type of the muramic acid was glycolyl. The predominant menaquinone was MK-9(H8). The 16S rRNA gene sequences of strains YM16-303(T) and YM16-304(T) were most similar to that of Ilumatobacter fluminis YM22-133(T), and phylogenetic analyses also indicated that they belong to the genus Ilumatobacter. Ilumatobacter fluminis YM22-133(T) and strains YM16-303(T) and YM16-304(T) should be classified as distinct species in the genus Ilumatobacter, however, since the 16S rRNA gene sequence similarity between them was low and the major cellular fatty acids and some physiological properties were different. Moreover, average nucleotide identity and maximal unique exact matches index values also supported the conclusion that they represent different species. On the basis of the above analyses, two novel species, Ilumatobacter nonamiense sp. nov. (type strain YM16-303(T) = NBRC 109120(T) = KCTC 29139(T)) and Ilumatobacter coccineum sp. nov. (type strain YM16-304(T) = NBRC 103263(T) = KCTC 29153(T)), are proposed. The order Acidimicrobiales, which contains the genus Ilumatobacter, currently includes six genera and only six species, and they are phylogenetically very far from each other. Phylogenetic analyses revealed that strains YM16-303(T) and YM16-304(T) clustered with closely related uncultured actinobacteria but not Ilumatobacter fluminis YM22-133(T), suggesting that many uncultured bacteria related to these isolates exist in the environment. This is the first report on interspecies relationships in the order Acidimicrobiales.

Complete genome sequence of phototrophic betaproteobacterium Rubrivivax gelatinosus IL144.

Rubrivivax gelatinosus is a facultative photoheterotrophic betaproteobacterium living in freshwater ponds, sewage ditches, activated sludge, and food processing wastewater. There have not been many studies on photosynthetic betaproteobacteria. Here we announce the complete genome sequence of the best-studied phototrophic betaproteobacterium, R. gelatinosus IL-144 (NBRC 100245).

A genome sequence-based approach to taxonomy of the genus Nocardia.

The genus Nocardia includes both pathogens and producers of useful secondary metabolites. Although 16S rRNA analysis is required to accurately discriminate among phylogenetic relationships of the Nocardia species, most branches of 16S rRNA-based phylogenetic trees are not reliable. In this study, we performed in silico analyses of the genome sequences of Nocardia species in order to understand their diversity and classification for their identification and applications. Draft genome sequences of 26 Nocardia strains were determined. Phylogenetic trees were prepared on the basis of multilocus sequence analysis of the concatenated sequences of 12 genes (atpD-dnaJ-groL1-groL2-gyrB-recA-rpoA-secA-secY-sodA-trpB-ychF) and a bidirectional best hit. To elucidate the evolutionary relationships of these genes, the genome-to-genome distance was investigated on the basis of the average nucleotide identity, DNA maximal unique matches index, and genome-to-genome distance calculator. The topologies of all phylogenetic trees were found to be essentially similar to each other. Furthermore, whole genome-derived and multiple gene-derived relationships were found to be suitable for extensive intra-genus assessment of the genus Nocardia.

Whole-genome analysis of Salmonella enterica serovar Typhimurium T000240 reveals the acquisition of a genomic island involved in multidrug resistance via IS1 derivatives on the chromosome.

Salmonella enterica serovar Typhimurium is frequently associated with life-threatening systemic infections, and the recent global emergence of multidrug resistance in S. enterica isolates from agricultural and clinical settings has raised concerns. In this study, we determined the whole-genome sequence of fluoroquinolone-resistant S. enterica serovar Typhimurium T000240 strain (DT12) isolated from human gastroenteritis in 2000. Comparative genome analysis revealed that T000240 displays high sequence similarity to strain LT2, which was originally isolated in 1940, indicating that progeny of LT2 might be reemerging. T000240 possesses a unique 82-kb genomic island, designated as GI-DT12, which is composed of multidrug resistance determinants, including a Tn2670-like composite transposon (class 1 integron [intI1, bla(oxa-30), aadA1, qacEΔ1, and sul1], mercury resistance proteins, and chloramphenicol acetyltransferase), a Tn10-like tetracycline resistance protein (tetA), the aerobactin iron-acquisition siderophore system (lutA and lucABC), and an iron transporter (sitABCD). Since GI-DT12 is flanked by IS1 derivatives, IS1-mediated recombination likely played a role in the acquisition of this genomic island through horizontal gene transfer. The aminoglycoside-(3)-N-acetyltransferase (aac(3)) gene and a class 1 integron harboring the dfrA1 gene cassette responsible for gentamicin and trimethoprim resistance, respectively, were identified on plasmid pSTMDT12_L and appeared to have been acquired through homologous recombination with IS26. This study represents the first characterization of the unique genomic island GI-DT12 that appears to be associated with possible IS1-mediated recombination in S. enterica serovar Typhimurium. It is expected that future whole-genome studies will aid in the characterization of the horizontal gene transfer events for the emerging S. enterica serovar Typhimurium strains.

In Silico Analysis of PKS and NRPS Gene Clusters in Arisostatin- and Kosinostatin-Producers and Description of Micromonospora okii sp. nov.

Micromonospora sp. TP-A0316 and Micromonospora sp. TP-A0468 are producers of arisostatin and kosinostatin, respectively. Micromonospora sp. TP-A0316 showed a 16S rRNA gene sequence similarity of 100% to Micromonosporaoryzae CP2R9-1T whereas Micromonospora sp. TP-A0468 showed a 99.3% similarity to Micromonospora haikouensis 232617T. A phylogenetic analysis based on gyrB sequences suggested that Micromonospora sp. TP-A0316 is closely related to Micromonospora oryzae whereas Micromonospora TP-A0468 is an independent genomospecies. As Micromonospora sp. TP-A0468 showed some phenotypic differences to its closely related species, it was classified as a novel species, for which the name Micromonospora okii sp. nov. is proposed. The type strain is TP-A0468T (= NBRC 110461T). Micromonospora sp. TP-A0316 and M. okii TP-A0468T were both found to harbor 15 gene clusters for secondary metabolites such as polyketides and nonribosomal peptides in their genomes. Arisostatin-biosynthetic gene cluster (BGC) of Micromonospora sp. TP-A0316 closely resembled tetrocarcin A-BGC of Micromonospora chalcea NRRL 11289. A large type-I polyketide synthase gene cluster was present in each genome of Micromonospora sp. TP-A0316 and M. okii TP-A0468T. It was an ortholog of quinolidomicin-BGC of M. chalcea AK-AN57 and widely distributed in the genus Micromonospora.

Diversity of nonribosomal peptide synthetase and polyketide synthase gene clusters in the genus Acrocarpospora.

Acrocarpospora is a rare, recently established actinomycete genus of the family Streptosporangiaceae. In the present study, we sequenced whole genomes of the type strains of Acrocarpospora corrugate, Acrocarpospora macrocephala, and Acrocarpospora pleiomorpha to assess their potency as secondary metabolite producers; we then surveyed their nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) gene clusters. The genome sizes of A. corrugate NBRC 13972T, A. macrocephala NBRC 16266T, and A. pleiomorpha NBRC 16267T were 9.3 Mb, 12.1 Mb, and 11.8 Mb, respectively. Each genome contained 12-17 modular NRPS and PKS gene clusters. Among the 23 kinds of NRPS and PKS gene clusters identified from the three strains, eight clusters were conserved in all the strains, six were shared between A. macrocephala and A. pleiomorpha, and the remaining nine were strain-specific. We predicted the chemical structures of the products synthesized by these gene clusters based on bioinformatic analyses. Since the chemical structures are diverse, Acrocarpospora strains are considered an attractive source of diverse nonribosomal peptide and polyketide compounds.

Complete genome sequence of the representative γ-hexachlorocyclohexane-degrading bacterium Sphingobium japonicum UT26.

Sphingobium japonicum strain UT26 utilizes γ-hexachlorocyclohexane (γ-HCH), a man-made chlorinated pesticide that causes serious environmental problems due to its toxicity and long persistence, as a sole source of carbon and energy. Here, we report the complete genome sequence of UT26, which consists of two chromosomes and three plasmids. The 15 lin genes involved in γ-HCH degradation are dispersed on the two chromosomes and one of the three plasmids.

Draft genome sequence of Actinomadura sp. K4S16 and elucidation of the nonthmicin biosynthetic pathway.

Actinomadura sp. K4S16 (=NBRC 110471) is a producer of a novel tetronate polyether compound nonthmicin. Here, we report the draft genome sequence of this strain together with features of the organism and assembly, annotation and analysis of the genome sequence. The 9.6 Mb genome of Actinomadura sp. K4S16 encoded 9,004 putative ORFs, of which 7,701 were assigned with COG categories. The genome contained four type-I polyketide synthase (PKS) gene clusters, two type-II PKS gene clusters, and three nonribosomal peptide synthetase (NRPS) gene clusters. Among the type-I PKS gene (t1pks) clusters, a large t1pks cluster was annotated to be responsible for nonthmicin synthesis based on bioinformatic analyses. We also performed feeding experiments using labeled precursors and propose the biosynthetic pathway of nonthmicin.

Draft genome sequence of Streptomyces hyaluromycini MB-PO13T, a hyaluromycin producer.

Streptomyces hyaluromycini MB-PO13T (=NBRC 110483T = DSM 100105T) is type strain of the species, which produces a hyaluronidase inhibitor, hyaluromycin. Here, we report the draft genome sequence of this strain together with features of the organism and generation, annotation and analysis of the genome sequence. The 11.5 Mb genome of Streptomyces hyaluromycini MB-PO13T encoded 10,098 putative ORFs, of which 5317 were assigned with COG categories. The genome harbored at least six type I PKS clusters, three type II PKS gene clusters, two type III PKS gene clusters, six NRPS gene clusters, and one hybrid PKS/NRPS gene cluster. The type II PKS gene cluster including 2-amino-3-hydroxycyclopent-2-enone synthetic genes was identified to be responsible for hyaluromycin synthesis. We propose the biosynthetic pathway based on bioinformatic analysis.

Reclassification of Nocardia species based on whole genome sequence and associated phenotypic data.

Type strains of 72 validated Nocardia species were phylogenetically analyzed based on the multilocus sequence analysis (MLSA) concatenated atpD-groL1-groL2-recA-rpoA-secY-sodA-ychF. Furthermore, their similarity based on digital DNA-DNA hybridization (dDDH) was calculated. Nocardia soli, Nocardia cummidelens and Nocardia salmonicida, Nocardia nova and Nocardia elegans, Nocardia exalbida and Nocardia gamkensis, and Nocardia coubleae and Nocardia ignorata formed coherent clades, respectively. Moreover, each set showed over 70% relatedness by dDDH and shared common phenotypic characteristics. Therefore, we propose a reclassification of Nocardia soli and Nocardia cummidelens as a later heterotypic synonym of Nocardia salmonicida, Nocardia elegans as a later heterotypic synonym of Nocardia nova, Nocardia gamkensis as a later heterotypic synonym of Nocardia exalbida, and Nocardia coubleae as a later heterotypic synonym of Nocardia ignorata.

An extracellular [NiFe] hydrogenase mediating iron corrosion is encoded in a genetically unstable genomic island in Methanococcus maripaludis.

Certain methanogens deteriorate steel surfaces through a process called microbiologically influenced corrosion (MIC). However, the mechanisms of MIC, whereby methanogens oxidize zerovalent iron (Fe0), are largely unknown. In this study, Fe0-corroding Methanococcus maripaludis strain OS7 and its derivative (strain OS7mut1) defective in Fe0-corroding activity were isolated. Genomic analysis of these strains demonstrated that the strain OS7mut1 contained a 12-kb chromosomal deletion. The deleted region, termed "MIC island", encoded the genes for the large and small subunits of a [NiFe] hydrogenase, the TatA/TatC genes necessary for the secretion of the [NiFe] hydrogenase, and a gene for the hydrogenase maturation protease. Thus, the [NiFe] hydrogenase may be secreted outside the cytoplasmic membrane, where the [NiFe] hydrogenase can make direct contact with Fe0, and oxidize it, generating hydrogen gas: Fe0 + 2 H+ → Fe2+ + H2. Comparative analysis of extracellular and intracellular proteomes of strain OS7 supported this hypothesis. The identification of the MIC genes enables the development of molecular tools to monitor epidemiology, and to perform surveillance and risk assessment of MIC-inducing M. maripaludis.

Draft Genome Sequence of an Anicemycin Producer, Streptomyces sp. TP-A0648.

We report the draft genome sequence of Streptomyces sp. TP-A0648 isolated from a leaf of Aucuba japonica This strain produces a new tumor cell growth inhibitor designated anicemycin. The genome harbors at least 12 biosynthetic gene clusters for polyketides and nonribosomal peptides, suggesting the potential to produce diverse secondary metabolites.

Draft Genome Sequence of Streptomyces sp. TP-A0874, a Catechoserine Producer.

We report the draft genome sequence of Streptomyces sp. TP-A0874 isolated from compost. This strain produces catechoserine, a new catecholate-type inhibitor of tumor cell invasion. The genome harbors at least six gene clusters for polyketide and nonribosomal peptide biosyntheses. The biosynthetic gene cluster for catechoserines was identified by bioinformatic analysis.