Bacteriophage and non-pathogenic vibrio to control diseases in black tiger shrimp (Penaeus monodon) aquaculture

Abstract

Abstract The study aimed to address the recurring outbreaks of microbial diseases in black tiger shrimp (Penaeus monodon) aquaculture in Bangladesh by utilizing bacteriophages and non-pathogenic Vibrio. Bacteriophages were isolated from sewage water collected from a shrimp farm, hatchery, and the JUST campus. The infectivity of the bacteriophages against various Vibrio strains was evaluated to determine their bacteriolytic activity. Non-pathogenic Vibrio strains were obtained from suspected diseased isolates collected from the south-western region of Bangladesh through PCR testing. In laboratory tests, the bacteriophages successfully infected 91% of the tested Vibrio strains (19 out of 21 strains). In the experimental unit, shrimp treated with phage prophylaxis and phage treatment exhibited significant protection against Acute Hepatopancreatic Necrosis Disease (AHPND) and survived a deadly bacterial challenge. PCR amplification identified five non-pathogenic Vibrio strains from a total of 35 suspected diseased isolates. Field trials were conducted, applying cultured bacteriophages at a concentration of 1.5x106 PFU/ml and non-pathogenic Vibrio at 5x105 CFU/ml. These trials demonstrated improved protection against infections and did not result in severe mortality during the adaptive research phase. Morphological tests conducted on the cultured shrimp revealed a muscle gut ratio greater than 4:1 and no abnormal deformities in the appendages or overall body of the shrimp, indicating their overall health and well-being. Bacteriological tests conducted on the shrimp samples showed an 18% bacterial infection rate, primarily involving Vibrio cholerae, Vibrio parahaemolyticus, and some other bacteria. However, these infections did not result in a disease outbreak. PCR amplification conducted in the fish molecular biology lab at JUST yielded negative results for AHPND, White Spot Syndrome Virus (WSSV), and Enterocytozoon hepatopenaei (EHP). These results highlight the potential of using bacteriophages and non-pathogenic Vibrio as a sustainable approach to prevent and control microbial diseases in shrimp aquaculture. The study provides valuable insights into the development of alternative strategies to combat antibiotic resistance and support the growth of the shrimp industry in Bangladesh.