Biosystematics of novel Streptomyces from mangrove in Malaysia SERHOOI LENG 2018 Members of family Actinobacteria, especially the genus Streptomyces have demonstrated exemplary performance in synthesizing bioactive compounds. By investigating various properties of the bacteria, the current study has identified four novel Streptomyces species from the poorly explored mangrove sediment in the east coast of Peninsular Malaysia. Among the four strains, extract of MUSC 136T showed highest toxicity towards colon cancer cells, probably triggering cell death via altering components of important pathways like p53 protein and intracellular glutathione levels. Altogether, these findings suggested that the exploration of new streptomycetes from underexplored area is a good strategy to discover useful bioactive compounds.