Evaluation of antioxidant producing potential of halophilic bacterial bionts from marine invertebrates.

Marine invertebrates exposed to high levels of reactive oxygen species in the oceans have been reported to produce antioxidants as a major defense against free radical mediated toxicity; protecting their tissues from the damage associated with the oxidative stress. In view of this, the present study was carried out to determine the antioxidant activity of 100 bacterial bionts isolated from marine sponges, corals and a single bivalve. Methanol extract of biont GUVFCFM-3 produced 67.83% scavenging of 2,2-diphenyl-2-picrylhydrazyl free radicals and 65.87% scavenging of superoxide free radicals. Preliminary tests leading to the identification of the extracellular antioxidant factor produced by GUVFCFM-3 revealed that it is a peptide. We report that the genera Chromohalobacter sp. primarily known for its unique salt tolerating abilities by virtue of the production of osmolytes is an excellent scavenger of free radicals.

Antibacterial activity of halophilic bacterial bionts from marine invertebrates of mandapam-India.

Marine ecosystem and its organisms, particularly the invertebrates are recent targets of bioprospecting and mining for a large group of structurally unique natural products encompassing a wide variety of chemical classes such as terpenes, polyketides, acetogenins, peptides and alkaloids of varying structures, having pronounced pharmacological activities. In view of the limited reports on the antibacterials produced by bacteria, isolated from marine sponges, corals and bivalves of Indian origin, the present study is aimed at investigating the antagonistic activities of 100 heterotrophic, halophilic bacterial bionts isolated from 9 sponges, 5 corals and one bivalve. Culture broths of 46 of these bionts were active against human pathogenic bacteria namely Staphylococcus citreus, Proteus vulgaris, Serratio marcesans, Salmonella typhi, Aerobacter aerogenes and Escherichia coli. Further, the ethyl acetate extracts of cell free supernatant confirmed the presence of extracellular bioactive factor, by agar cup diffusion method. Interestingly, highest number of bionts having activity was isolated from corals followed by sponges and bivalve. The study clearly demonstrates that bacterial bionts of marine invertebrates are a rich source of bioactive secondary metabolites against human bacterial pathogens.