Photobacterium damselae ssp. damselae associated with diseased black tiger shrimp Penaeus monodon Fabricius in India

Abstract

To characterize and identify Photobacterium damselae ssp. damselae present in black gill diseased Penaeus monodon collected from east coast of India. Photobacterium damselae ssp. damselae was isolated from hepatopancreas, muscles and gills by using the thiosulfate citrate bile salts sucrose agar supplemented with 1.5% NaCl (TCBS-1) medium. A total of 32 Ph. damselae ssp. damselae isolates were studied together with two reference strains. The biochemical tests and analysis of ureC and 16S rRNA genes confirmed the phenotypic characterization of the isolates as Ph damselae ssp. damselae. Experimental infection studies revealed that the LD50 values of P. monodon and P. indicus ranged from 2x10(3) to 5x10(5) CFU per shrimp and from 4x10(2) to 2x10(4) CFU per shrimp, respectively. Photobacterium damselae ssp. damselae was found in the internal organs of P. monodon and it showed pathogenic to shrimp. This is the first study on the Ph. damselae ssp. damselae present in the black gill diseased P. monodon in India and therefore might serve as a basis for future studies and diagnosis purpose to shrimp culturists.