Aquaculture has been affected by the appearance of various diseases, mainly of bacterial and viral origin, and is considered the leading cause of loss of production in crops. In 2009, a disease of bacterial origin called "acute hepatopancreatic necrosis disease" (AHPND) was reported for the first time in China, capable of causing massive mortalities, up to 100% of production during the first 30 days of culture, significantly affecting the species Penaeus monodon and Penaeus vannamei. Different strains of Vibrio sp. were identified as the causative agent of this disease, which secrete a delta-endotoxin called PirAB, encoded by the pirA and pirB genes in a conjugative plasmid (pVA1).
The control of bacterial problems in shrimp farms has often relied on the use of antibiotics. However, these products’ inappropriate and excessive use has led to health problems and the development of resistant bacterial strains. This misuse has also stimulated the transfer of resistance genes, exacerbating the issue.
Our study aims to design a microbial consortium that could be a significant change in the fight against AHPND in the Pacific white shrimp (P. vannamei) postlarvae. This consortium, if successful, could serve as a promising alternative to the use of antibiotics. The consortium will be carried out by purifying bacterial strains isolated from commercial probiotics and the digestive tract of healthy shrimp postlarvae. Pure isolates and their extracellular products were subjected to in vitro antagonism tests by means of various plate techniques such as well diffusion, disc diffusion, cross streak, and direct challenge by disc diffusion (figure 1), then the bacterial strains with the best antagonistic activity on AHPND-Vibrio campbellii strains will be selected. Mixtures of the potential probiotics will be used to evaluate them in an in vivo challenge using P. vannamei postlarvae infected with an AHPND-V. campbellii strain. Preliminary results will be presented.