The fate of probiotic species applied in intensive grow-out ponds in rearing water and intestinal tracts of white shrimp, Litopenaeus vannamei

Introduction - Probiotics have been commonly practiced in commercial shrimp farms to increase pond production. However, these possibilities were based on the results of in vitro studies or laboratory in vivo trials. While studies on probiotic applications in commercial-scale farms are still rarely investigated, this study addresses the fate of probiotic species in ponds and the intestinal tract of white shrimps reared in an intensive aquaculture system.Material and methods - Four commercial probiotic species (Lactobacillus plantarum, Lactobacillus fermentum, Bacillus subtilis, and Pseudomonas putida) were applied to the commercial shrimp ponds (@800 m(2) area of high-density polyethene ponds) in the morning at a dose of 5 ppm once every 2 days in the first month, and once a week from second month onward. Then, the presence of the probiotic species was traced by collecting the rearing water and shrimp's intestines on day 47 of culture to monitor their composition and abundance using high-throughput sequencing.Results - None of the commercial probiotic species could be detected from both rearing water and shrimp intestinal tracts. These results suggest that the probiotic species had low viability and adaptability in the rearing pond as well as the shrimp intestines when applied on commercial-scale farms. These facts may explain the high variation in the yield among shrimp ponds in spite of having similar treatments.Conclusion - Probiotic strains had low viability and adaptability in commercial farms. Thus, methods and strategies in probiotic application to commercial-scale shrimp farms should be evaluated and further developed to increase probiotic efficacy.