CHARACTERIZATION OF AN ANTIMICROBIAL AND ANTIOXIDANT COMPOUND FROM A MARINE BACTERIUM GSA10 ASSOCIATED WITH THE SPONGE HALICHONDRIA GLABRATA

Abstract

Three marine sponges- Halichondria glabrata, Sigmadocia petrosioides and Pseudosuberitus andrewsi were collected for isolation of sponge-associated bacteria from Mumbai coastal regions. Among 110 isolates, six strains were selected and studied for its antibacterial activity by disc-diffusion assay. TLC- Bioautography studies were performed. GSA10 isolate from Halichondria glabrata was selected for showing good antagonistic activity for E. coli MTCC-1687, P. aeruginosa MTCC- 1688, B. subtilis MTCC- 441 and S. aureus MTCC - 737. Various biochemical tests and 16S ribosomal RNA sequencing were performed for GSA10 for its identification which confirmed it to be a Bacillus species. To decipher the activity of GSA10 bacteria, we aligned the 16S rRNA sequence in NCBI database. It represented close relationship with pG1 Bacillus amyloliquefaciens and hypothetical protein ATP synthase from Staphylococcus aureus. TLC direct bioautography was developed and results were found positive for a specific band at Rf 6.8. This bioactive compound was isolated by preparative TLC and characterized by UV, FT-IR, and LC-MS. It was further evaluated for antioxidant activity. It showed good antioxidant activity in DPPH scavenging (99%) and TRAP assay (91%).The purified compound was characterized as a C-30 hopanoid from a marine-sponge associated bacteria.