Selection of Bacillus spp. isolates having enzyme producing ability and antagonistic to Vibrio parahaemolyticus causing the early mortality syndrome (EMS) on shrimp

Abstract

The aim of this study is to select some Bacillus isolates which are capable of yielding several beneficial enzymes and antagonism to Vibrio parahaemolyticus causing the EMS shrimp disease. In this study, we isolated and screened total of 54 Bacillus isolates from 30 mud, water and shrimp samples at shrimp ponds in Soc Trang province. Among these, 19 isolates were resistant against Vibrio parahaemolyticus strains causing the EMS shrimp disease via two testing methods. Three of them including NA2B13, NA10B2, NA8B1 isolates showed strongresistance and strong one to three kinds of extracellular enzymes to produce. Result of 16S rDNA sequencing and MALDI -TOF showed that NA2B13 and NA8B1 were Bacillus subtilis and NA10B2 was B. amyloliquefaciens. These two species were regarded safe and having potential applications in the production of biological products to prevent EMS shrimp disease.