Aquaculture production is increasingly looking towards innovative solutions to further improve gut health and production sustainability. Marine probiotics have the potential to support the control of infections and to improve zootechnical performances, while minimizing the environmental impact. We investigated the probiotic potential of Bacillus multi-strain consortium extracted from the marine environment and encapsulated in algae on white shrimps, Penaeus vannamei.
Materials and methods
20-day and 60-day feeding trials were conducted respectively on healthy Penaeus vannamei PL10 (n=3500, triplicate) and PL25 (n=350, triplicate) to evaluate the effects on growth and health parameters of a marine probiotic consortium (MPC) made of four marine Bacillus strains encapsulated in algae when used as dietary supplement.
At the end of the 60-day trial, the treatment with MPC at 0.1% significantly improved growth performance (final body weight, weight gain, specific growth rate) and significantly decreased feed conversion ratio of White Shrimp P. vannamei (P < 0.05). Supplementation with MPC at 0.1% also significantly decreased the occurrence of total Vibrio spp. count in shrimp’s hepatopancreas under normal conditions (P < 0.05). Overall, MPC significantly enhanced the mRNA expressions of (1) digestive genes in hepatopancreas, such as Trypsin, α-Amylase, Triacylglycerol lipase and Chymotrypsin BII; (2) immune-related genes, such as proPO, crustin genes in hepatopancreas and Dual Oxidase, mucin-like peritrophin, Penaeidin-3α in intestine genes (P < 0.05) ), especially with MPC at 0.25%. Under challenge conditions, MPC significantly increased disease resistance of shrimp larvae against V. parahaemolyticus (VpAHPND) (P < 0.05).
The results of high-throughput sequencing showed a significant improvement in White Shrimps digestive tract bacterial communities when supplemented with probiotics. Moreover, the MPC enhanced the hepatopancreas gene pathway related to metabolisms of endocrine, immune and digestive systems. In addition, the beneficial effects observed in intestine gene pathway were mainly related to translation, transport catabolism, and signal transduction.
This study demonstrated the ability of the marine Bacillus spp. consortium encapsulated in algae to improve White Shrimp growth performance, digestive tract & immune status and disease resistance during both larval and grow-out phases.