Screening of antibacterial producing actinomycetes from sediments of the Caspian Sea

Document Type : Original Article

Authors
1 Department of Molecular and Cell Biology, University of Mazandaran, Babolsar, Iran
2 Department of Microbiology, University of Tehran, Tehran, Iran
3 Caspian Sea Ecology Research Institute, Sari, Iran
Abstract
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 gramnegative 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). All of the 24 isolates were active against at least to one of the test organisms. The MN38 strain
showed activity against Staphylococcus aureus (20.0±0.5mm), Bacillus subtilis (27.0±0.2 mm), and Escherichia
coli (20.0±0.3 mm). The MN39 strain was also active against E. coli (23.0±0.4mm), B. subtilis (23.0±0.2mm),
Klebsiella pneumonia (24±0.1mm), whereas, the MN3 strain showed activity against Pseudomonas aeruginosa
(20.0±0.2mm). The results of this investigation revealed that the marine actinomycetes of Caspian Sea sediments
were potent source of novel antibiotics and bioactive compounds.
Keywords