Streptomyces sp. isolated from marine sediment collected from Palk Strait, Bay of Bengal was investigated for its antagonistic potential. The isolate exhibited antimicrobial activity against selected bacterial strains of clinical importance such as Staphylococcus aureus MTCC 3160, Bacillus pumilus NCIM 2327, S. aureus (methicillin resistant), Escherichia coli MTCC 1698, E. coli (ESBL), Shigella flexneri MTCC 1457, Proteus vulgaris and Enterobacter cloacae. Phenotypic and molecular characterization ascertained the isolate BDK01 as Streptomyces chumphonensis. Media optimization with one variable-at-a-time strategy was attempted to identify the ideal concentrations of starch (5-15 g/l), casein (0.01-0.05 g/l), NaCl 1.0-3.0 g/l, pH (4.0-9.0 g/l), temperature (25-45 °C) and inoculum level (0.5-5 ml) towards achieving maximum antimicrobial compound production. Statistical optimization of production media was carried by establishing an 11 variables 17 run experiment through PB model which evinced starch, calcium carbonate, pH and inoculum concentration that highly influenced bioactive compound production. Spectral data of active ethyl acetate extract revealed the presence of various bioactive compounds such as Salicyl alcohol, N-phenyl benzamide. 6-Octadecenoic acid, (Z), 1,3,5-Cycloheptatriene. Antiproliferation activity of active fraction against MCF-7 Cell line exhibited IC 50 value of 9.5 µg/ml. Overall, it is observed that the marine actinomycete S. chumphonensis BDK01 could be employable as promising strain for novel antimicrobial and cytotoxic metabolites.

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Objective: The main objective of the current investigation is to identify the antagonistic potential of marine sediment actinobacterial population collected from coastal regions of Tamil Nadu and Kerala.Methods: A total of 60 marine sediment samples were collected from 27 locations of coastal Tamil Nadu and Kerala. A total of 85 morphologically distinct actinobacterial strains were isolated and taxonomically characterized. The strains were screened for its antagonistic potential against selected bacteria strains, and the obtained results were statistically analyzed. Further, the strains excelled in producing antimicrobial substances were subjected to electron microscopic and chemotaxonomic studies to get more taxonomic details.Results: The isolates were identified as different species of Streptomyces, Micromonospora, Saccharopolyspora, Actinopolyspora, Nocardia, Nocardioides, Kitasatospora, and the rest of them were categorized as “unidentified.” All the isolates were subjected to antimicrobial assay through cross-streak and well diffusion methods that endorsed 34 (40%) of them to be active against clinical and reference bacterial strains such as Staphylococcus aureus MTCC 3160, S. aureus (methicillin-resistant), Bacillus pumilus NCIM 2327, Escherichia coli MTCC 1698, E. coli, Shigella flexneri MTCC 1457, and Proteus vulgaris. The predominance of Streptomyces (18) was ascertained and followed by Saccharopolyspora (7), Micromonospora (5), Nocardia (2), and Kitasatospora (2) with considerable antimicrobial activities. Statistical analysis revealed that the isolates BDK01, BMT01, BPY03, and BRS07 showed significant antimicrobial activities. Phenotypic and chemotaxonomic analysis revealed that all four isolates are belonging under Streptomyces genus.Conclusion: The output of the present investigation revealed that the Streptomyces species are predominant in marine sediments and gain more attention for their antagonistic potential. Therefore, assessment and evaluation of marine microbial diversity were done, which could serve as a potential source for novel antibiotics.

Genus Streptomyces under phylum actinobacteria has been recognized as a prolific source for production of bioactive secondary metabolites. Actinobacterial strain designated as SKCMM1 isolated from Pichavaram Mangrove forest sediment was identified as Streptomyces cavourensis using polyphasic taxonomic approach. This strain shares 99% sequence similarity with Streptomyces cavourensis NBRC 13026 T. Ethyl acetate fraction of the strain SKCMM1 exhibited highest biological activity. FTIR and GCMS analysis of crude compounds isolated from the active ethyl acetate fraction states the presence of several phenolic, hydrocarbon and fatty acid compounds with various bioactivities. This study will be an attempt to understand that the strain holds significant antimicrobial activity against test pathogens and antiproliferative activity against HeLa cell lines (IC 50 value of 8.9µg/ml).

Objective: The main objective of the current investigation is to identify the antagonistic potential of marine sediment actinobacterial population collected from coastal regions of Tamil Nadu and Kerala.Methods: A total of 60 marine sediment samples were collected from 27 locations of coastal Tamil Nadu and Kerala. A total of 85 morphologically distinct actinobacterial strains were isolated and taxonomically characterized. The strains were screened for its antagonistic potential against selected bacteria strains, and the obtained results were statistically analyzed. Further, the strains excelled in producing antimicrobial substances were subjected to electron microscopic and chemotaxonomic studies to get more taxonomic details.Results: The isolates were identified as different species of Streptomyces, Micromonospora, Saccharopolyspora, Actinopolyspora, Nocardia, Nocardioides, Kitasatospora, and the rest of them were categorized as “unidentified.” All the isolates were subjected to antimicrobial assay through cross-streak and well diffusion methods that endorsed 34 (40%) of them to be active against clinical and reference bacterial strains such as Staphylococcus aureus MTCC 3160, S. aureus (methicillin-resistant), Bacillus pumilus NCIM 2327, Escherichia coli MTCC 1698, E. coli, Shigella flexneri MTCC 1457, and Proteus vulgaris. The predominance of Streptomyces (18) was ascertained and followed by Saccharopolyspora (7), Micromonospora (5), Nocardia (2), and Kitasatospora (2) with considerable antimicrobial activities. Statistical analysis revealed that the isolates BDK01, BMT01, BPY03, and BRS07 showed significant antimicrobial activities. Phenotypic and chemotaxonomic analysis revealed that all four isolates are belonging under Streptomyces genus.Conclusion: The output of the present investigation revealed that the Streptomyces species are predominant in marine sediments and gain more attention for their antagonistic potential. Therefore, assessment and evaluation of marine microbial diversity were done, which could serve as a potential source for novel antibiotics.