Extracellular Enzymes Produced by Vibrio alginolyticus Isolated from Environments and Diseased Aquatic Animals

A total of 17 Vibrio alginolyticus isolates were obtained from environments, diseased fish and shrimp using CHROMagar Vibrio and confirmed by biochemical tests and PCR targeted to the gyrB gene. They were investigated for production of exoenzymes. All of the isolates from diseased fish and shrimp (n = 8) showed gelatinase, lecithinase, and caseinase activities, while 75% (6/8) of them possessed amylase and lipase activities. In environmental isolates (n = 9), the gelatinase and lecithinase activities were detected in all isolates. Four out of nine isolates (44%) possessed lipase, while 67% (6/9) of environmental isolates were positive for both caseinase and amylase activities. Interestingly, α-hemolysin activity was detected in all V. alginolyticus isolates from diseased fish and shrimp but it was detected in only 44% (4/9) of the environmental isolates, suggesting that they might be involved in bacterial pathogenesis. The arbitrarily primed polymerase chain reaction (AP-PCR) technique showed distinct DNA profiles of all isolates consisting of 7 to 11 bands ranging from 0.3 – 6.0 Kb (with a common band of 1.2 Kb). Fourteen DNA profiles were obtained from a dendrogram analysis with 20% maximum similarity. These results indicate genetically heterogenicity among V. alginolyticus.