Isolation and molecular identification of diversified Vibrios from cultured shrimp (Penaeus monodon) from the south-western region of Bangladesh

Diversified Vibrios from shrimp of Bangladesh

Abstract

Aquaculture is a fast-growing food producing industry that plays a significant role in employment generation and protein supply. In Bangladesh, the southwestern region, especially the districts of Khulna, Satkhira and Bagerhat, is a major hub of shrimp aquaculture. This study was conducted to isolate and identify the Vibrio diversity in cultured Penaeus monodon via classical microbiological and molecular approaches. Samples were collected from shrimp farms in the three southwestern districts of Khulna, Satkhira, and Bagerhat. Bacterial isolation was performed using the conventional agar plate method, followed by molecular identification through 16S rRNA gene sequencing. A total of 80 bacterial isolates were initially screened, and 21 representative isolates were selected for molecular identification. Based on nucleotide BLAST analysis using the NCBI database, six isolates were identified as Vibrio mediterranei, while four isolates each were identified as V. cholerae, and V. parahaemolyticus. One isolate each was identified as Photobacterium damselae subsp. damselae, V. vulnificus, V. alginolyticus, V. harveyi, V. plantisponsor, and Vibrio sp. In addition, one strain of Bacillus subtilis was isolated and identified, reflecting the widespread use of probiotics in contemporary shrimp farming practices. A phylogenetic tree was constructed using the maximum likelihood method in MEGA 12 software to confirm the evolutionary relationships between the bacteria isolates and reference strains. Our results provide valuable insight into the diversity of Vibrio species present in shrimp farms, including potentially pathogenic species, and offer scientific evidence to support disease management and control in shrimp aquaculture.

J. Bangladesh Acad. Sci. 50(3); 369–382: September 2026