Bioprospecting and Detection of NRPS Gene of Sea Cucumber Stichopus monotuberculatus Symbiont-bacteria Against Microbial Fish Pathogens Aeromonas hydrophila and Vibrio harveyi

Abstract

Vibriosis and septicemia are infections caused by bacteria that rise many problems on aquaculture industry. Bioprospection of marine organisms such as sea cucumber are very promising as they are widely known to contain symbiotic microorganisms having antibacterial potential. This study aimed to analyze the antibacterial potential of sea cucumber Stichopus monotuberculatus symbiont bacteria against Aeromonas hydrophila and Vibrio harveyi, as well as to detect its NRPS gene. The research methods used were the isolation of symbiotic bacteria in the gut of the sea cucumber S. monotuberculatus, screening for its antibacterial activity, identification of 16S rRNA, and detection of NRPS gene clusters. A total of 16 bacteria were isolated, where 12 isolates had the potential to inhibit the pathogen A. hydrophila and 7 isolates had the potential to inhibit the growth of the pathogenic V. harveyi. Based on the identification of 16S rRNA, the symbiotic bacteria that was able to inhibit the growth of A. hydrophila was Bacillus subtilis, whereas bacteria that inhibited the pathogen of V. harveyi was Bacillus flexus. B. subtilis and B. flexus were detected to have NRPS gene clusters with an amplicon size of about 250 bp.