Application of probiotics in Prevention of acute hepatopancreatic necrosis disease (AHPND) on penaeus vannamei

Abstract

Acute Hepatopancreatic Necrosis Disease (AHPND), caused by the pathogen Vibrio parahaemolyticus, is responsible for mass mortality in shrimp at a rate of 40-100%. Until now, many methods have been used to treat the disease, but these seem to be ineffective. Thus, using probiotic could be one of the most bio-methods for reducing this disease. In this study, Bacillus licheniformis (B1) was isolated from fish gut and identified through API 50CHB and API 20E test strips and 16S rRNA sequences. The antimicrobial activities were tested in co-culture of different concentrations of V. parahaemolyticus and probiotic strain in Broth medium. It showed that at the concentrations of B1: 105 CFU ml-1 and 107 CFU ml-1, the probiotic displayed strong antagonistic activity to V. parahaemolyticus (at concentrations 104, 105, and 107 CFU ml-1) from 9-h and 3-h, respectively. Moreover, excreting bacteriocin from B1 could inhibit the growth of V. parahaemolyticus at 103, 104, 105 CFU ml-1 for 6 hours. Although the densities of V. parahaemolyticus increased from 9-h to 12-h, the OD values were significantly different from those of the control groups (p<0.05). The toxicity of B1 to Penaeus vannamei shrimp was tested by mixing shrimp feed with B1 strain at the concentrations of 105, 107, 109 CFU kg-1/feed. Shrimp were feed with these mixture for 10 days but no mortality was found in any treatments. It can be concluded that probiotic strain-B1 might have a broad potential application for inhibiting pathogenic Vibrio spp. in vitro. Keywords: Vibrio parahaemolyticus AHPND Penaeus vannamei Probiotic Bacillus licheniformis Growth inhibition