Abstract
Among the various bacterial pathogens associated with the aquaculture environment, Vibrio parahaemolyticus the important one from shrimp and human health aspects. Though having been around for several decades, phage-based control of bacterial pathogens (phage therapy) has recently re-emerged as an attractive alternative due to the availability of modern phage characterization tools and the global emergence of antibiotic-resistant bacteria. In the present study, a total of 12 V. parahaemolyticus specific phages were isolated from 264 water samples collected from inland saline shrimp culture farms. During the host range analysis against standard/field isolates of V. parahaemolyticus and other bacterial species, lytic activity was observed against 2.3-45.5% of tested V. parahaemolyticus isolates. No lytic activity was observed against other bacterial species. For genomic characterization, high-quality phage nucleic acid with concentrations ranging from 7.66 to 220 ng/µl was isolated from 9 phages. After digestion treatments with DNase, RNase and S1 nuclease, the nature of phage nucleic acid was determined as ssDNA and dsDNA for 7 and 2 phages respectively. During transmission electron microscopy analysis of phage V5, it was found to have a filamentous shape making it a member of the family Inoviridae. During efficacy study of phage against V. parahaemolyticus in shrimp, 78.1% reduction in bacterial counts was observed within 1 h of phage application. These results indicate the potential of phage therapy for the control of V. parahaemoyticus in shrimp. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12088-021-00934-6.