GENETIC DIVERSITY ON Aeromonas hydrophila ISOLATED FROM HEMORRHAGIC STRIPED CATFISH IN THE MEKONG DELTA

Abstract

This study was conducted to evaluate the genetic diversity of Aeromonas hydrophila isolates collected from striped catfish intensively farmed in the Mekong Delta. A total of 26 bacterial isolates were obtained from hemorrhagic disease-infected fish. All bacterial isolates were identified as A. hydrophila based on their morphological characterization, API 20E kit, and molecular biology technique. Twelve strains were selected as representatives for sequencing the aerolysin gene; these strains had high identities (96.64 – 100%) compared with reference strains of A. hydrophila on Genbank. Besides, these strains were used for analyzing genetic diversity. The results indicated that the isolates from Tien Giang and Tra Vinh had a close relationship and shared distant similarities with the strains from An Giang, Ben Tre, Dong Thap, and Vinh Long provinces. The study has found genetic differences between A. hydrophila isolates in two main groups representing two ecologically different areas of brackish and fresh water in the Mekong Delta.