Probiotic Bacillus species to mitigate acute hepatopancreatic necrosis disease (AHPND) in shrimp aquaculture

Abstract:Acute hepatopancreatic necrosis disease (AHPND) is caused by Vibrio species that secrete the toxin PirAB, resulting in significant shrimp mortality by degenerating the epithelial cells of the hepatopancreas. Various mitigation strategies have been explored, but their implementation has often been inadequate or ineffective. In this study, we developed an in vitro probiotic selection pipeline to identify Bacillus strains that could potentially mitigate AHPND. Bacillus strains were tested for in vitro inhibition of an AHPND strain, quorum sensing (QS) disrupting abilities, secretome profiles, lectin binding profile and PirAB toxin degradation. Bacillus strains could be divided into four groups. Group 1 showed a distinct secretome profile 3, strong N-acylhomoserine lactone (AHL, a quorum sensing molecule) and PirB degrading capacity, wheat germ agglutinin (WGA) lectin binding preference, and low glycan diversity. Group 2 was characterized by secretome profile 1, strong AHL degrading capacity, no PirB degrading capacity, WGA lectin binding preference and high glycan diversity. Group 3 showed secretome profile 1, no AHL or PirB degrading capacity, concanavalin A (ConA) lectin binding preference and a high glycan diversity. Group 4 was characterized by secretome profile 2, no AHL or PirB degrading capacity, ConA lectin binding preference and low glycan diversity. Next, B. megaterium LMG9300 of group 1, the only PirB degrading strain, was used at a 5 × 107 CFUmL−1 during a Penaeus vannamei immersion challenge test with Vibrio parahaemolyticus strain TW01, enhancing shrimp survival by 15 %, though not significantly compared to the challenge control. A probiotic mixture, including B. megaterium LMG9300 (group 1), B. megaterium DSM1668 (group 2), and B. licheniformis DSM12370 (Group 4), each at 5 × 106 CFUmL−1, was also tested and significantly increased survival by 40 % compared to the challenge control, suggesting that composing mixtures with diverse in vitro characteristics might be a promising strategy.

Publication year:2026

Keywords:Food & animal science & technology, Aquatic sciences

Accessibility:Closed