GC-MS based identification of anti-microbial bioactive compounds, isolated from Bacillus halotolerans of marine sediment

Marine environments are known for their complex habitats due to the spread of industrial pollutants, and microorganisms that endure adverse conditions are evolving as extremophiles. The present study is designed to explore the antimicrobial activity of microbes present in marine ecosystems that secrete bioactive compounds. The bacterial strains VT-2, VT-4, and VT-5 isolated from the marine sediment exerted an inhibitory effect against the human pathogenic microorganisms Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa). Among the three strains, VT-5 exhibited efficient antibiotic potential. Based on biochemical characterisation, the VT-5 strain is gram-positive, rod-shaped, and demonstrates resilience to stress, salt, and drought. The 16 s r-RNA analysis confirmed Bacillus halotolerans, having a similarity of 99.75%. Bioactive compounds released by the VT-5 strain had efficient antibacterial activity, which was also observed in FESEM micrographs as deformation of cellular structure in pathogens. The chromatographic extraction of VT-5 was identified to have antibacterial bioactive compounds, and that was further determined by using FTIR and GC/MS. The peaks observed in the FTIR spectrum with different functional groups showed similarity to the structures of these isolated bioactive compounds. GC/MS analysis also revealed the presence of nine vital bioactive compounds, most of which have been reported to exhibit antimicrobial activity. Our study further strengthens that VT-5 (Bacillus halotolerans) is resistant to MDR (Pseudomonas aeruginosa) and MRSA (Staphylococcus aureus) pathogenic strains. Furthermore, this study explores marine-associated microbes as a promising avenue for new antimicrobial drugs, revealing possibilities for marine organism-derived compounds.