Genomic analysis, tolerance, and probiotic potential of Bacillus coagulans mr-1B isolated from the hindgut of Macrobrachium rosenbergii against Vibrio parahaemolyticus

The global Macrobrachium rosenbergii aquaculture industry is plagued by Vibrio parahaemolyticus-induced diseases. Antibiotic overuse further exacerbates antimicrobial resistance and ecological hazards, creating an urgent need for eco-friendly control strategies. In this study, Bacillus coagulans mr-1B was isolated from the hindgut of healthy M. rosenbergii to evaluate its probiotic potential. The strain was identified via 16 S rDNA sequencing, with its genomic characteristics analyzed using Nanopore-Illumina hybrid whole-genome sequencing. Its efficacy was validated through in vitro assays (tolerance to high temperature, acid, and bile salts; biofilm inhibition) and in vivo challenge tests. Results showed that mr-1B harbors biosynthetic gene clusters for antimicrobial metabolites. It retained 26.4% survival at 90 °C and 60.1% survival at pH 3.0, and effectively disrupts mature V. parahaemolyticus biofilms. After V. parahaemolyticus challenge, the 14-day mortality of M. rosenbergii fed with mr-1B was only 9% (vs. 92% in the positive control), with no safety risks. In conclusion, B. coagulans mr-1B exhibits excellent anti-Vibrio activity and stress tolerance, serving as a promising probiotic candidate for green control of vibriosis in M. rosenbergii aquaculture, which aligns with the demands of green aquaculture.