Isolation, Screening and Identification of Marine bacteria for their Potential Bioactivity

Bacteria in marine environment are the most versatile organisms capable of producing a wide spectrum of potential bioactive secondary metabolites, some with novel structures. Many of these secondary metabolites of marine bacterial origin have been explored to develop new antimicrobial compounds. Aim: To study the inhibitory activity of metabolites produced by isolated marine bacteria water samples from marine environment were collected from ten random sites of Bheemli shore, Visakhapatnam, Bay of Bengal Coast, Andhra Pradesh. The samples were brought to the lab in sterile containers, made into composite sample which was utilized for the isolation of bacteria employing Zobell agar medium. Results: 23 representative isolates of bacterial strains were obtained from the water sample after inoculation and incubation on Zobell agar medium. The isolates were designated as C1, C2, C3, C4 and so on. Colony characteristics of all the pure isolates, Gram staining nature and shape of the cells were recorded. The obtained bacterial isolates were screened for their antibacterial activity against selected Gram- positive and Gram- negative groups of test pathogens. Of the 23 bacterial isolates screened, only 12 isolates showed growth inhibitory activity against the test bacteria. Among the 12 isolates positive for antibacterial activity, isolates viz., C1, C6, C7, C8 and C9 were found to have potential with relatively high inhibitory activity. Conclusion: The five potential isolates were investigated by 16S rRNA gene sequencing for the species identification and revealing the C1 identified as Bacillus paramycoides, C6 as Lysinibacillus fusiformis, C7 as Bacillus oshimensis, C8 as Bacillus velezensis, and C9 as Bacillus paranthracis. Further work on isolation, purification and identification of metabolite compounds from the most potential bacterial species is in progress.