A newly isolated strain of Bacillus subtilis W2Z exhibited probiotic effects on juvenile red claw crayfish, Cherax quadricarinatus

Abstract

Aquaculture traditionally used antibiotics, leading to environmental contamination, food residue, and antibiotic-resistant superbugs. Probiotics offer a promising antibiotic alternative. In this study, a strain of Bacillus subtilis W2Z was isolated from aquaculture environments and can inhibit pathogens in aquaculture food production through chemical compounds. Eight-weeks C. quadricarinatus cultivation experiments revealed that B. subtilis W2Z, as a probiotic, contributes to increasing the yield of red claw crayfish. The supplementation of strain W2Z in the feed enhanced the crayfish's resistance to Aeromonas hydrophila by increasing immune-related enzyme activity and improving intestinal microbiota. B. subtilis W2Z has significant potential as a bioresource for exploring probiotics in crustacean aquaculture. Adding B. subtilis W2Z to C. quadricarinatus feed at a concentration of 1 × 108 to 1 × 109 colony forming unit (CFU)/g is recommended.