SEDIMENTS, SEC 4 • SEDIMENT-ECOLOGY INTERACTIONS • RESEARCH ARTICLE Diversity and antibiotic-producing potential of cultivable marine-derived actinomycetes from coastal sediments of Turkey Kadriye Özcan & Semiha Çetinel Aksoy & Orçun Kalkan & Ataç Uzel & E. Esin Hames-Kocabas & Erdal Bedir Received: 23 November 2012 / Accepted: 3 June 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Purpose Marine environments, especially sediments, are rich sources of actinomycetes that provide many bioactive compounds, primarily antibiotics. The goal of this study was to investigate the diversity of cultivable actinomycetes and their potential to produce antibiotics from sediments collect- ed from the coastal zones of Turkey. Materials and methods Thirty sediment samples were col- lected from nine different coastal sites in three seas surround- ing the Anatolian Peninsula of Turkey. Of the samples, 6 were collected from one site in the Black Sea, 18 from seven sites in the Aegean Sea, and 6 from one site in the Mediterranean Sea. Strains of pure actinomycetes were isolated by modified acti- nomycetes isolation agar (MAIA), M1 agar, M6 agar, and modified R2A agar. Ethyl acetate extracts and fermentation broths were used for the evaluation of antimicrobial activity against antibiotic resistant test microorganisms. The identifi- cation of the isolates was undertaken by 16S rRNA gene sequencing. Results and discussion A total of 261 strains of actinomy- cetes were isolated, of which 66 (25 %) were active against at least one antibiotic-resistant microorganism. Sixty-five of the actinomycetes isolates with antimicrobial activity were Streptomyces spp. and one was Nocardia sp., which implied that genus Streptomyces was predominant. Whereas MAIA agar was the best medium to recover actinomycetes, M6 agar was superior to others for the isolation of antibiotic-producing strains. Conclusions Extensive screening of the extracts from the 261 isolates for antimicrobial activities revealed considerable po- tential to produce antibiotics. These findings imply that acti- nomycetes from marine sediments of the Anatolian Peninsula coasts have potential for the discovery of novel bioactive compounds. Keywords Anatolian Peninsula . Antimicrobial activity . Biodiversity . Coastal marine sediments . Marine derived actinomycetes 1 Introduction Actinomycetes (Actinomycetales; Actinomyces) is derived from the Greek word “actis” for beam and “mykes” for mucus, fungus. Actinomycetes are Gram-positive bacteria that are mostly aerobic and mycelial, and are characterized by high guanine–cytosine (GC) contents. Actinomycetes are morpholog- ically rod-shaped and their colonies form fungus-like branched networks of hyphae (Holt 1994). These bacteria play vital roles in turnover of organic matter and the formation of humus by decomposing recalcitrant organic materials such as keratin, lig- nocelluloses, and chitin (Goodfellow and Williams 1983; McCarthy and Williams 1992). Actinomycetes also produce volatile substances such as geosmin that give soils their charac- teristic “wet earthy scent” (Wilkins 1996). Actinomycetes of the genus Streptomyces are known to produce commercial antimi- crobial compounds. For instance, nearly 80 % of the antimicro- bial compounds that have been characterized are derived from Streptomyces spp. (Jensen et al. 2005a; Bull and Stach 2007). Responsible editor: Sabine Ulrike Gerbersdorf K. Özcan : S. Ç. Aksoy : O. Kalkan : A. Uzel (*) Department of Biology, Basic and Industrial Microbiology Section, Faculty of Science, Ege University, 35100 Bornova, Izmir, Turkey e-mail: atac.uzel@ege.edu.tr A. Uzel e-mail: atacuzel@gmail.com E. E. Hames-Kocabas : E. Bedir Department of Bioengineering, Faculty of Engineering, Ege University, 35100, Bornova, Izmir, Turkey J Soils Sediments DOI 10.1007/s11368-013-0734-y