Antagonism of marine Actinomycetes bacteria against virulence and bio-luminescence disease causing Vibrio harveyi

Luminescence is caused by Vibrio harveyi, which is responsible for causing mass mortality (80 - 100%) among Penaeus monodon hatcheries. An alternative strategy is the use of marine Actinomycetes to control V. harveyi. Eighty three marine Actinomycetes bacteria were isolated from marine and brackishwater of Muttukadu, Chennai and treated against growth and virulence factors produced by V. harveyi. Among 83 Actinomycetes isolates, 2 (CBWA3 and CBWA10) showed higher zone of inhibition against V. harveyi. When the Actinomycetes isolates were co-cultured with V. harveyi, the growth of V. harveyi was reduced to 4.66 log cfu mL⁻¹ by CBWA3 and 3.75 log cfu mL⁻¹ by CBWA10. The virulence factors like luminescence, crude bacteriocin, protease production and phospholipase activity were determined during co-culture and it was observed that phospholipase activity was very high in control and virulence was weak in the treatment. This study confirms that marine Actinomycetes bacterial isolates can be effectively utilized to control luminescence disease in the aquaculture system