Isolation and Identification of Two Pathogenic Strains Associated with Vibriosis of Shrimp Larvae

Abstract:

Two pathogenic strains zouA and zouB were isolated from Litopenaeus vannamei larvae which suffered from vibriosis, and were identified as Vibrio alginolyticus and V. parahaemolyticus by traditional bacterial identification method respectively. Strain zouB was confirmed further as V. parahaemolyticus by special R72H sequence test. 16S rRNA and heat shock protein (HSP60) genes partial sequences of strain zouA were determined. Phylogenetic tree of vibrios based on 16S rRNA gene sequences revealed that there was more than 98% sequence identity among zouA, V. alginolyticus, V. parahaemolyticus, et al., and could not be distinguished between each other. HSP60 gene sequences showed that strain zouA had sequence identity of more than 98% to V. alginolyticus, whereas had less than 92% to that of all the other vibrios. Combining phenotypic and molecular characters, zouA and zouB were identified as V. alginolyticus and V. parahaemolyticus respectively.