Isolation of Hg and Cu resistant Streptomyces from marine sediments in different regions of the Caspian Sea

Abstract

Expansion of industrial activities; mining and metal plating could cause release of high amount of heavy metals into seawater and marine sediment resulting in heavy metal resistant microorganisms. Due to the important role of Streptomyces in production of secondary metabolites, the reduction ability of enzymes and elements was used to study the resistance exhibited by Streptomyces in the isolation of heavy metals (copper and mercury) from marine sediments and coastal waters of the Caspian Sea. Marine sediments samples were collected from coastal locations aseptically. The media of Starch Casein agar (SCA), and Kusters agar (KUA) were used for the isolation of Streptomyces and biochemical testes like lipid, casein, starch and gelatin hydrolysis and etc. was carried out for identification of this bacteria and determination of heavy metals (Hg, Cu) resistant strains was performed with well diffusion assay and for detection of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) Micro dilution assay was used. Also, amounts of heavy metals in different parts of coastal waters were measured with atomic absorption spectrophotometry assay. A total of 41 Streptomyces were isolated from coastal locations 7 strains (17.07%) showed copper resistant to 1000 mg/L, 4 strains (9.75%) showed mercury resistant. The strains C9, D11 and E16 to 20 mg/L and C2 to 40 mg/L were mercury resistant. Due to existence of heavy metals (Hg, Cu) resistant Streptomyces in the Caspian Sea, researcher can use them as well suited agents for Bioremediation.