Anti-quorum Sensing Activity and Bioactive Components of Marine-derived Bacteria

Understanding and harnessing quorum sensing activity and identifying bioactive substances produced by marine-derived bacteria are essential for exploring their potential applications in various fields, including biotechnology, pharmaceuticals, and environmental management. This research aims to investigate the quorum-sensing activities employed by these bacteria and to characterize the bioactive compounds they produce, to unlock their therapeutic, industrial, and ecological potentials. This study focuses on screening, isolation and characterization of marine bacteria from Thoothukudi Harbour Beach, India, and potential antibacterial and anti-quorum sensing activities of their respective spent media against biofilm forming pathogens. Three soil samples were collected and processed for bacterial isolation. Seventeen different bacterial isolates were obtained and identified after prior culture. Antibacterial activity was evaluated against four pathogenic bacteria, with some isolates demonstrating significant inhibition. Additionally, biofilm inhibition assays were conducted, revealing the ability of certain isolates to inhibit the formation of biofilms. The secondary metabolites present in the ethyl acetate fraction of I.B 6 isolate exhibiting relatively high antibacterial and antibiofilm properties were identified by GC-MS. Anti-quorum sensing activity was also investigated using swarming assay and the MIC was determined accordingly for the ethyl acetate fraction. Hence, these marine bacteria hold for producing bioactive compounds with potential pharmaceutical and industrial applications. Finally, the positive organism is subjected to 16S rRNA sequencing for identification and was found to be Bacillus thuringiensis.