Sponge diversity along the coasts of Andaman and Nicobar Islands comprises about 126 species and sponges are known to act as a host to endosymbionts, which is found to possess novel antimicrobial metabolites. In the present study screening and characterization of antibiotic producing endosymbiotic bacteria from the marine sponge Lamellodysidea herbacea (Keller, 1889) was investigated. Eight isolated bacterial strains from the sponge were screened for bioactivity against human pathogens Escherichia coli (MTCC 443), Bacillus cereus (MTCC 430), Bacillus subtilis (MTCC 121), Listeria monocytogenes (MTCC839), Staphylococcus aureus (MTCC 3160) and Salmonella enterica typhimurium (MTCC 1252) and only two strains CAB1 and CAB38 exhibited activity. Ethyl acetate extracted metabolites of strain CAB1 showed significant activity against four pathogens B. cereus, B. subtilis, S. aureus and S. entrica typhimurium and CAB38 against three pathogens B. subtilis, E. coli and S. entrica typhimurium. The 16S rRNA gene sequence of these two strains showed 99% sequence similarity with known sequences in the GenBank and their phyologenetic analysis confirmed strain CAB1 as Bacillus amyloliquefaciens (MK135790) and CAB38 as Alcaligenes faecalis (MK135791). The study demonstrated that metabolites from sponge associated bacterial endosymbionts can be a major source of unique compounds with potential bioactivity.
Key words: Andaman Sea; Bioactive metabolites; Endosymbiotic bacteria; L. herbacea.
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