Shewanella algae: An emerging pathogen of black spot disease in freshwater-cultured whiteleg shrimp (Penaeus vannamei)

Abstract

Black spot disease causes significant economic losses in whiteleg shrimp Penaeus vannamei yet only limited information is available on Shewanella algae as a bacterial pathogen of this disease. In this study, a virulent strain, temporarily named SFH3, was isolated from diseased freshwater-cultured P. vannamei suffering from black spot disease, identified phenotypically and molecularly as S. algae. A phylogenetic tree was constructed to examine the taxonomic position and relatedness of isolate SFH3 to other S. algae isolates. When screened against a range of common veterinary antibiotics, isolate SFH3 is apparently susceptible to aminoglycosides and quinolones antibiotics in aquaculture. To the best of our knowledge, this is the first report of S. algae as a causal agent of black spot disease in live freshwater-cultured P. vannamei.