Evaluation of Streptomyces as probiotics against vibriosis and health management of prawn larvae Macrobrachium rosenbergii

摘要

Nearly forty-five isolates of Streptomyces were found to be associated with 16 different seaweeds. Of these, only six strains that antagonized Vibrio vulnificus were selected to study the probiotic efficiency.? Six strains were characterized based on the phenotypic characteristics.? The toxicity of different Vibrio species (V. harveyji, V. parahemolyticus, V. alginolyticus, V. vulnificus) towards prawn larvae were studied, among them, V.vulnificus was more pathogenic and mass mortality (88%) was observed within three days. Hence, Streptomyces that antagonized V. vulnificus with maximum inhibition zone was selected for the probiotic study.? In vitro and in vivo evaluation of probiotic efficacy of six selected Streptomyces were made using prawn larvae Macrobrachium rosenbergii challenged with V. vulnificus at 105Cfu/ml. The best growth-rate, reduced mortality, highest glucose and protein-level, reduced chole-sterol level and increased enzymatic activities were noticed with Streptomyces AQB.SKKU8, AQB.SKKU18, AQB.SKKU25 treated groups. It is recommended to use strain AQB.SKKU 8, Strain AQB.SKKU 18, strain AQB.SKKU 25, and strain AQB.SKKU37, as probiotics in-vivo, while strain AQB.SKKU10, and strain AQB.SKKU20 showed probiotic effects in-vitro only. The results of the present investigation reveal that the seaweed associated Streptomyces were found to be a promising source of probiotic and biocontrol agents against vibriosis disease in aquaculture.