Actinomycetes are interesting as a main producer of secondary metabolites and industrial antibiotics from marine environments. A total of 44 strains of actinomycetes were isolated from Caspian Sea sediments at a depth of 5-10 m. Preliminary screening was done using cross-streak method against 2 gram-positive and 4 gram-negative pathogen bacteria. The most potent strains MN2, MN3, MN38, MN39, MN40, MN41, and MN44 were used to extract the antibacterial substances. The antibacterial activities were performed using Kirby-Bauer disk diffusion method. Potent actinomycetes were screened for hydrolytic exoenzymatic activities (amylase and protease). Of all the 24 isolates were active again at least one of the test organisms. The strain MN38 showed activity against Staphylococcus aureus (20.0ñ0.5mm), Bacillus subtilis (27.0ñ0.2 mm), and Escherichia coli (20.0ñ0.3 mm). The strain MN39 was also active against E. coli (23.0ñ0.4mm), B. subtilis (23.0ñ0.2mm), Klebsiella pneumonia (24ñ0.1mm), whereas the strain MN3 showed activity against Pseudomonas aeruginosa (20.0ñ0.2mm). The results of this investigation revealed that the marine actinomycetes of Caspian Sea sediments were potent source of novel antibiotics and bioactive compounds.
