Antibacterial and brine shrimp lethality effect of marine actinobacterium Streptomyces sp. CAS72 against human pathogenic bacteria

ObjectiveTo investigate the in vitro antibacterial activity against human pathogenic bacteria and brine shrimp lethality bioassay of the marine actinobacterium.MethodsForty six marine actinobacterial strains were isolated from sediment samples of Uppanar estuary, Cuddalore, India. Preliminary screening was done by cross-streak method and the potential strain was identified by morphological, chemotaxonomical and molecular methods. Fermentation was done and the metabolite was obtained by liquid-liquid extraction using ethyl acetate and purified by silica gel (100–200 mesh) column chromatography. The purified metabolite was tested for antibacterial activity, minimal inhibitory concentration and brine shrimp lethality bioassay.ResultsAmong the forty six strains, CAS72 was found effective against human pathogenic bacteria. The strain CAS72 was identified as Streptomyces sp. The purified metabolite exhibited a significant in vitro antibacterial activity. The MIC value was also determined against human pathogenic bacteria and a strong cytotoxic activity in brine shrimp lethality assay was observed and the LC50 value was 23.5 μg/mL.ConclusionsThe present investigation reveals that the marine actinobacteria are well obtainable in Uppanar estuary environment and it can provide a definite source for novel bioactive metabolites.