Streptomyces axinellae sp. nov., isolated from the Mediterranean sponge Axinella polypoides (Porifera).
ABSTRACT An actinomycete strain, isolated from the marine sponge Axinella polypoides collected from Banyuls-sur-Mer, France, was characterized using a polyphasic approach. Based on its chemotaxonomic and morphological characteristics, strain Pol001(T) belongs to the genus Streptomyces. The strain is characterized by ll-diaminopimelic acid in the cell wall, menaquinones MK-9(H(4), H(6), H(8)) and a DNA G+C content of 71.0 mol%. It forms a separate phyletic line based on phylogenetic analyses of the nearly complete 16S rRNA gene sequence. Strain Pol001(T) could be differentiated from other closely related Streptomyces species with validly published names by phenotypic and genotypic analysis. DNA-DNA hybridization between strain Pol001(T) and closely related reference strains further confirmed that strain Pol001(T) represents a novel taxon of the genus Streptomyces. Therefore, it is proposed that strain Pol001(T) represents a novel species in the genus Streptomyces, Streptomyces axinellae sp. nov.; the type strain is Pol001(T) (=DSM 41948(T) =CIP 109838(T)).
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ABSTRACT: The distribution of the streptomycin (strA) and viomycin (vph) resistance genes was examined in Streptomyces isolates. It was hypothesised that non-antibiotic producers that are niche competitors with producers will need to possess resistance to the antibiotic and will thus have acquired resistance genes. A detailed phylogenetic study, utilizing a novel multilocus sequence typing (MLST) scheme, was made of a collection of isolates and types strains with a Streptomyces griseus phenotype in addition to type strains from known producers of streptomycin and related compounds. strA and vph were found either within a biosynthetic gene cluster or independently. S. griseus strains possessing the streptomycin cluster formed part of a clonal complex and have been readily isolated from soil originating in every continent except Antarctica. Few copies of strA were detected in soil total community DNA, none of which were identical to the gene from the streptomycin cluster. All S. griseus strains possessing solely strA belonged to two clades and were closely related to streptomycin producers. The strA in the resistance-only strains is likely to have originated from the self-resistance gene of another aminoglycoside cluster and arrived in those S. griseus strains via horizontal gene transfer. S. griseus strains with only vph also formed two clades and were more distantly related to the producers than to one another. The high sequence divergence of the viomycin resistance genes also suggests that the vph homologue arrived in these two groups from another peptide antibiotic cluster via horizontal gene transfer. The expression of the strA gene was constitutive in resistance-only strains from both subgroups whereas streptomycin producers showed peak strA expression in late log phase which correlates with the switch on of streptomycin biosynthesis. One example of horizontal gene transfer of the streptomycin cluster was discovered, to a Streptomyces platensis strain, which contained a cluster with 84% sequence identity and almost identical gene structure and arrangement to that of the S. griseus cluster. Its expression pattern was also highly similar to that of S. griseus producers, but at a much lower level. Whilst there is evidence that antibiotics have diverse roles in nature, this work clearly supports the co-evolution of resistance in the presence of antibiotic biosynthetic capability within closely related soil dwelling bacteria. This reinforces the view that, for some antibiotics at least, the primary role is one of antibiosis during competition in soil for resources.
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ABSTRACT: The aim of the study was to screen the antifungal activity of the crude extract prepared from the strain Streptomyces spp. VITSTK7 against Aspergillus sp. and to characterize the isolate. A total of 8 strains were isolated from the marine sediments collected at the Puducherry coast, India. All the eight strains were primarily screened for antifungal activity against three species of Aspergillus namely A. fumigatus, A. niger and A. flavus. Our search resulted in the isolation of a potential strain VITSTK7. The production media was optimized for maximum yield of secondary metabolites. The metabolites were extracted using ethyl acetate, lyophilized and screened for antifungal activity against the three Aspergillus species by well diffusion method. A maximum zone of inhibition (21 mm) was observed for A. fumigatus in comparison with the standard antifungal antibiotic Nystatin (20 mm). This potential strain was further identified based on Hideo Nonomura classification. A phylogenetic tree was constructed by maximum parsimony method to identify up to the species level. Molecular taxonomy and phylogeny revealed that the strain belonged to the genus Streptomyces and was designated as Streptomyces spp.VITSTK7. Blast search of the 16s rRNA sequence of the strain with the sequences available in the NCBI data bank showed a maximum similarity of 86% with Streptomyces longisporoflavus (DQ 442520) with the bootstrap value of 100. The 16s rRNA sequence of the strain Streptomyces spp.VITSTK7 was submitted to the GenBank under the accession number GQ 499369. The secondary structure of 16s rRNA and the restriction sites were also predicted using Genebee and NeBCutter online softwares, respectively.
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ABSTRACT: Actinomycetes are prolific producers of pharmacologically important compounds accounting for about 70% of the naturally derived antibiotics that are currently in clinical use. In this study, we report on the isolation of Streptomyces sp. strains from Mediterranean sponges, on their secondary metabolite production and on their screening for anti-infective activities. Bioassay-guided isolation and purification yielded three previously known compounds namely, cyclic depsipeptide valinomycin, indolocarbazole alkaloid staurosporine and butenolide. This is the first report of the isolation of valinomycin from a marine source. These compounds exhibited novel anti-parasitic activities specifically against Leishmania major (valinomycin IC(50) < 0.11 microM; staurosporine IC(50) 5.30 microM) and Trypanosoma brucei brucei (valinomycin IC(50) 0.0032 microM; staurosporine IC(50) 0.022 microM; butenolide IC(50) 31.77 microM). These results underscore the potential of marine actinomycetes to produce bioactive compounds as well as the re-evaluation of previously known compounds for novel anti-infective activities.Marine Drugs 02/2010; 8(2):373-80. DOI:10.3390/md8020373 · 3.51 Impact Factor