Screening and Characterization of Sponge-Associated Bacteria Producing Bioactive Compounds Anti-Vibrio sp.

In Indonesia, vibriosis is the main disease in shrimp. This disease is caused by Vibrio sp that may decrease the productivity of shrimp cultivation. Thus, exploration for new bioactive compounds as vibriosis biocontrol agent is necessary. Marine sponge-associated bacteria is one of many sources for bioactive compounds. The aim of this study was to screen marine sponge-associated bacteria producing anti-Vibrio sp’s bioactive compounds. Total 12 bacterial isolates (15%) of 80 isolates was isolated from marine sponges Hyrtios sp, Verongula sp. and Smenospongia sp. had anti-Vibrio sp activity in different spectra. The hemolytic assay showed that these 12 bacteria were not pathogen. Interestingly, 3 out of 4 potential isolates with the best anti-Vibrio activity have been confirmed to have genes involved in the synthesis of bioactive compounds, mainly Polyketide Synthase (PKS) and Non-Ribosomal Peptide Synthetase (NRPS) based on the occurrence of Ketosynthase (KS) and Adenilase (A) domain, respectively. Based on 16S rRNA gene, those four isolates were highly homolog to the Bacillus sp in different species and strains. Isolate coded as P2.24 was the only bacterium that had the widest spectrum of anti-Vibrio bioactive compounds against three Vibrio sp used i.e., Vibrio harveyi, V. parahaemolyticus, V. vulnificus. Consistently, an anti- Vibrio sp. activity of the P2.24 was also shown by antagonism assay using culture, supernatant and crude extract of the isolate. Our study indicates this bacterial isolate potentially to be further exploited for controlling vibriosis biologically and important for elucidation of bioactive compounds synthesized by this bacterium.