Biological Properties of Actinomycetes Isolated from Marine Sponges in Madagascar

Marine actinomycetes are well known as a potential provider of novel bioactive compounds and currently considered as an important source of natural substances with unique chemical diversity. In this study, 20 marine actinomycetes were isolated from three Demospongia collected in the South East coast of Madagascar. Cultural, morphological, physiological and biochemical characteristics of the isolates showed that they belong to the genus Streptomyces. The Antimicrobial activity of the strains was performed using the agar cylinder technique against pathogens bacteria, yeast and fungi. It resulted that 90% of the isolates showed activity against at least one or more of the test germs. The isolates were more active against Gram-positive bacteria than Gram-negative bacteria. Simultaneously, ethanol extracts of the isolates were tested for their antioxidant activity using DPPH (1,1-Diphenyl-2-picrylhydrazyl) free radical scavenging test. Among tested extracts, those of Streptomyces M9 and M17 showed antioxidant activity against DPPH free radical with IC50 values of 12.8µg/ml and 12.4µg/ml, respectively.