Anti-Vibrio Compounds from Digestive Symbiont Bacteria of Whiteleg Shrimp (Litopenaeus vannamei) from Traditional Ponds in Kaur, Bengkulu, Indonesia as Probiotic Candidates for Shrimp Aquaculture

Kaur Regency is one of the areas with high potential for whiteleg shrimp pond cultivation, but it often faces shrimp deaths and crop failure due to infection with pathogenic Vibrio spp. and antibiotic resistance. One alternative preventive is to utilise potential symbiotic bacteria from the digestive tract that can produce anti-Vibrio and enzymatic activities. This study aimed to select potential digestive symbiont bacteria based on their anti-Vibrio ability through isolation, purification, identification, biochemical tests, and anti-Vibrio tests. Candidates showing activity were further tested for toxicity, hemolysin, effectiveness, enzymatic, and molecular identification. Out of 40 digestive symbiont isolates, two Bacillus isolates of the γ-hemolytic type, namely ALF 3 and ALF 6, showed the most potential against seven pathogenic Vibrio spp. isolates (OALF 1, OALF 2, OALF 3, OALF 5, WALF 7, WALF 8, and WALF 10) from the digestive tract and infected whiteleg shrimp pond water, with toxicity percentage of 86.67-100 %, α and β-hemolytic type pathogenicity in BA. Based on their anti-Vibrio activity, amylolytic and proteolytic abilities, ALF 3 and ALF 6 were identified as Bacillus stercoris and Bacillus amyloliquefaciens, respectively, with effectiveness percentages of 89.7-100 % for B.stercoris, 87.7-100 % for B.amyloliquefaciens, and 97.7-100 % for the consortium compared to the treatment without co-culture with potential bacteria against the Vibrio spp. population growth in TCBSA media. This study highlights the potential of whiteleg shrimp digestive symbiont bacteria to enhance immunity against vibriosis while providing safe digestive enzymatic potential for whiteleg shrimp and humans as a potential probiotic candidate.