Marine actinomycetes, Streptomyces sp. - MSU29 was isolated from marine sponge Ircinia sp. from Cape Comorin Coast, India. Attempts were made for optimization of culture conditions for antibiotic production by Streptomyces. sp. The isolate exhibited optimal antibiotic production at 3% NaCI. The antibiotic production was found to be at maximum levels after 120h of incubation and thereafter gradually declined. The culture medium adjusted to pH 7.0 supported the antibiotic production compared to other pH and optimum temperature for antibiotic production was found to be 30°C. The medium supplemented with glycerol and Soybean meal as sole carbon and nitrogen sources respectively was proved to be the best for bioactive metabolites production. Among minerals tested, k2hpo4 displayed higher antibiotic production by the strain compared to other mineral supplements. So far only a few salt - tolerant actinomycetes have been explored for media optimization for their bioactive potential. Hence an attempt has been made to optimize culture conditions for secondary metabolites production to meet industrial demand.

Key words: antagonism, actinomycetes, antibiotics, Streptomyces sp., sponge, Ircinia sp.