DIRECT-FED PROBIOTICS IMPROVE SURVIVAL IN SHRIMP, Litopenaeus vannamei,  UNDER AHPND/EMS CHALLENGE

Daniel Taylor, Ann Stevens, Moonyoung Choi, David Drahos, Seth D'Imperio, Stephen Smith, Jared Heffron, David Kuhn
Department of Food Science and Technology
402F Human and Agricultural Biosciences
Virginia Tech, Blacksburg, VA, USA 24061
dpt@vt.edu

Diseases affecting shrimp contribute to billions of dollars of economic loss yearly to the global aquaculture industry. In 2009, a new strain of Vibrio parahaemolyticus causing Early Mortality Syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND) in shrimp emerged with a devastating and ongoing impact on global shrimp production. Alternatives to antibiotics and disinfectants, such as probiotic treatments, are emerging as attractive methods of pathogen control in shrimp culture. Probiotics can act as natural immune enhancers and provide pathogen-antagonistic action.  The overall project goal is to improve intensive shrimp production through direct application of probiotics in aquaculture feeds. It is hypothesized that direct-fed probiotics will colonize in the shrimp gut, enhance nutrient utilization, and indirectly provide increased disease resistance against pathogenic bacteria. Accordingly, we conducted the following studies in a biosafety level 2 (BSL2) laboratory to: (1) confirm the germination of different strains of Bacillus subtilis spores in the shrimp gut, (2) evaluate how to consistently infect shrimp (Litopenaeus vannamei) with an AHPND strain of V. parahaemolyticus using controlled-challenge studies, and (3) determine the effectiveness of probiotics, containing various strains of Bacillus subtilis, for decreasing AHPND disease impact. Challenge studies were conducted to evaluate the ability of direct-fed probiotics to improve shrimp gut health and reduce pathogenicity of the AHPND strain in shrimp.    Particular strains of Bacillus subtilis were capable of significantly (P<0.05) enhancing survival of shrimp (Figure 1). The commercial application of specific strains of direct-fed probiotics at shrimp farms could help reduce disease outbreaks of AHPND.