Anti-Vibrio harveyi Property of Micrococcus luteus Isolated from Rearing Water under Biofloc Technology Culture System

Biofloc culture system of shrimp is currently gaining wide acceptance since it increases production efficiency and lowers the risk of disease occurrence. The biofloc culture system is known to improve the water quality and it has been observed that this culture system tends to inhibit the population of pathogenic Vibrios. It is the intention of present work to isolate, characterize and identify bacterial species with potent anti-Vibrio activity from the biofloc technology culture system. Results indicate the presence of bacteria with Vibriostatic activity in the biofloc culture system. Identification revealed that the active bacteria is Micrococcus luteus exhibiting an optimum Vibrio lytic activity at 20 ppt and at a pH of around 8. Competitive gut colonization assay shows that the isolated bacteria has a higher gut colonizing activity than that of the pathogenic Vibrio harveyi. In conclusion M. luteus isolated from the biofloc technology culture system exhibited Vibrio lytic activity in vitro and gut colonizing activity in vivo.