Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis Syndrome (AHPNS) is an epizootic bacterial infection of shrimp. This disease, attributed to pathogenic Vibrio parahaemolyticus strains (VP-EMS), threatens shrimp aquaculture production and global food security. A valuable and alternative approach to using antibiotics for pathogen control, is the practice of incorporating direct-fed microbes (DFM) or probiotics to improve host survival and overall animal health.
Two DFM products, a single specific strain within Bacillus subtilis, and a blend of five strains of Bacillus from four different species (subtilis, amyloliquifaciens, megaterium, and brevis) were evaluated at various concentrations as feed additives (applied as a top coat on commercial feed) or as water additions for their ability to provide Litopenaeus vannamei shrimp protection against the EMS/AHPNS disease. Accordingly, the following assessments involved twenty-one, 20 L systems which allowed exploration of seven treatments performed in triplicate. Each trial consisted of a negative control (no VP-EMS exposure, no probiotic) and positive control (VP-EMS exposure, no probiotic), allowing for five additional probiotic treatment groups, which were fed and exposed to VP-EMS in the same manner as the positive control. Disease-challenge experiments demonstrated that while both Bacillus probiotic products were shown to significantly (p<0.05) improve shrimp survival, one specific strain provided the most consistent protection over several trials. These results also demonstrated that prophylaxis is reliant upon concentration, regardless of application. Specific probiotic strains positively influenced survival of shrimp with regard to EMS disease, serving as a promising alternative to traditional pathogen control in shrimp aquaculture.