... or on the sediments (Moriarty, 1998) So, we isolated Bacillus spp from intestine of P monodon captured from natural habitat and tested for antagonistic activity to pathogenic bacteria in aquaculture ... inhibit the growth of the pathogenic bacteria; Bacillus W806, Bacillus W902, Bacillus WL01 and Bacillus W1106 showed competitively exclude the pathogenic bacteria So, the presence of these Bacillus ... isolated from the intestine of Penaeus monodon collected from the Gulf of Thailand at Chonburi province Every month, during October 2005 to September 2006, 10 samples of shrimp (weight > 80 g) were investigated...