ABSTRACT
Objective: This study was aimed to isolate and screen marine sponge-associated bacteria producing anti-Vibrio compounds and to identify their compounds from the bacterial extract. Methods: Sponge-associated bacteria were isolated by spread plate method. Their anti-Vibrio activity against Vibrio parahaemolyticus, V. harveyi, and V. vulnificus was determined by dual culture test. Three potential isolates were identified based on 16S-rRNA gene analysis. All isolates producing anti-Vibrio compounds was tested for their haemolytic characters in blood agar medium. Anti-Vibrio activity of the most potential isolate was also tested by using its supernatant, extract, and concentrated culture. Chemical composition of crude extract derived from that isolate was identified by GC-MS analysis. Results: 68 bacterial isolates have been isolated from the marine sponge, Spongia sp., Svenzea sp., Ircinia sp., and Igernella sp. Of 68 isolates, 15 (22%) isolates had anti-Vibrio activities in various spectra against three Vibrio species, including V. harveyi, V. parahaemolyticus, and V. vulnificus. All isolates producing anti-Vibrio compounds were non-haemolytic. Bacterial isolates coded as D6.6, D6.19, and P4.17 have broad spectra. They could inhibit at least two Vibrio species as indicated by the clear zone formed around bacterial colonies. Based on 16S-rRNA, these isolates were closely related (similarity ≥ 99%) to Brevibacterium casei strain M Sw oHS, Bacillus altitudinis strain FJAT 47750, and Bacillus altitudinis strain PgBe190, respectively. D6.6 isolate was the most potential isolate, which could inhibit three Vibrio species. Consistently, its anti-Vibrio activity also confirmed by their supernatant, concentrated culture, and crude extract of that isolate. The crude extract derived from this isolate contained 10 major compounds that are biologically active. Conclusion: This study suggests that 15 bacteria strains isolated from marine sponges were potentially could inhibit Vibrio’s growth in vitro. These isolate could be further explored as anti-Vibrio agent.