Exclusion of Vibrio spp. by an antagonistic marine actinomycete Streptomyces rubrolavendulae M56

A marine actinomycete Streptomyces rubrolavendulae M56 isolated from the sediments of Bay of Bengal and displaying biogranulation property was used for the study. The strain showed antagonistic property against vibrios, the opportunistic pathogens in aquaculture. The efficacy of the biogranules of actinomycete M56 in competitive exclusion of Vibrio spp. was tested both in vitro and in vivo. Streptomyces rubrolavendulae M56 biogranules could significantly exclude the pathogenic Vibrio spp. in co‐culture experiments (in vitro). In vivo exclusion of Vibrio spp. in a Penaeus monodon postlarval rearing system was evaluated by treatment of the rearing water with biogranules of S. rubrolavendulae M56. The experiments proved that S. rubrolavendulae M56 biogranules could reduce the pathogenic Vibrio spp., while maintaining total heterotrophic bacterial count. Therefore, the actinomycete biogranules (M56) can be used as a promising alternative to antibiotics in the shrimp larval production system which is often affected by vibriosis.