Taxonomy and chemical characterization of new antibiotics produced by Saccharothrix SA198 isolated from a Saharan soil

Actinomycete strain SA198, isolated from a Saharan soil sample of Algeria, exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria, and phytopathogenic and toxinogenic fungi. The morphological and chemotaxonomic characteristics of the strain were consistent with those of the genus Saccharothrix. Analysis of the 16S rRNA gene sequence of strain SA198 showed a similarity level ranging between 97.2 and 98.8% within Saccharothrix species, S. australiensis being the most closely related. Two new active products were isolated by reverse HPLC using a C18 column. The ultraviolet–visible (UV–VIS), infrared (IR), mass, and 1Hand 14C nuclear magnetic resonance (NMR) spectra showed that these products were new bioactive compounds. The minimum inhibitory concentrations of these antibiotics showed a strong activity against fungi and moderate activities against Gram-positive and Gram-negative bacteria

Streptomyces asenjonii sp. nov., isolated from hyper-arid Atacama Desert soils and emended description of Streptomyces viridosporus Pridham et al. 1958

A polyphasic study was undertaken to establish the taxonomic status of Streptomyces strains isolated from hyper-arid Atacama Desert soils. Analysis of the 16S rRNA gene sequences of the isolates showed that they formed a well-defined lineage that was loosely associated with the type strains of several Streptomyces species. Multi-locus sequence analysis based on five housekeeping gene alleles showed that the strains form a homogeneous taxon that is closely related to the type strains of Streptomyces ghanaensis and Streptomyces viridosporus. Representative isolates were shown to have chemotaxonomic and morphological properties consistent with their classification in the genus Streptomyces. The isolates have many phenotypic features in common, some of which distinguish them from S. ghanaensis NRRL B-12104T, their near phylogenetic neighbour. On the basis of these genotypic and phenotypic data it is proposed that the isolates be recognised as a new species within the genus Streptomyces, named Streptomyces asenjonii sp. nov. The type strain of the species is KNN35.1bT (NCIMB 15082T = NRRL B-65050T). Some of the isolates, including the type strain, showed antibacterial activity in standard plug assays. In addition, MLSA, average nucleotide identity and phenotypic data show that the type strains of S. ghanaensis and S. viridosporus belong to the same species. Consequently, it is proposed that the former be recognised as a heterotypic synonym of the latter and an emended description is given for S. viridosporus

Streptomyces asenjonii sp. nov., isolated from hyper-arid Atacama Desert soils and emended description of Streptomyces viridosporus Pridham et al. 1958

A polyphasic study was undertaken to establish the taxonomic status of Streptomyces strains isolated from hyper-arid Atacama Desert soils. Analysis of the 16S rRNA gene sequences of the isolates showed that they formed a well-defined lineage that was loosely associated with the type strains of several Streptomyces species. Multi-locus sequence analysis based on five housekeeping gene alleles showed that the strains form a homogeneous taxon that is closely related to the type strains of Streptomyces ghanaensis and Streptomyces viridosporus. Representative isolates were shown to have chemotaxonomic and morphological properties consistent with their classification in the genus Streptomyces. The isolates have many phenotypic features in common, some of which distinguish them from S. ghanaensis NRRL B-12104T, their near phylogenetic neighbour. On the basis of these genotypic and phenotypic data it is proposed that the isolates be recognised as a new species within the genus Streptomyces, named Streptomyces asenjonii sp. nov. The type strain of the species is KNN35.1bT (NCIMB 15082T = NRRL B-65050T). Some of the isolates, including the type strain, showed antibacterial activity in standard plug assays. In addition, MLSA, average nucleotide identity and phenotypic data show that the type strains of S. ghanaensis and S. viridosporus belong to the same species. Consequently, it is proposed that the former be recognised as a heterotypic synonym of the latter and an emended description is given for S. viridosporus

Structurally diverse metabolites from the rare actinobacterium Saccharothrix xinjiangensis.

The bioassay-guided fractionation from cultures of the actinobacterium Saccharothrix xinjiangensis Act24Zk, collected from the Caspian Sea beach in Iran led to the isolation of three new compounds, caerulomycin M (1), saccharopyrone (2), and saccharonoic acid (3), together with the known compound, caerulomycin A (4). Their structures were elucidated from HR-ESIMS and 1D and 2D NMR data. Compound 2 displayed moderate cytotoxic activity against the human cervix carcinoma HeLa cells KB3.1 with an IC50 value of 5.4 µM