Diversity and antimicrobial activity of culturable actinobacteria isolated from the sediment of Sarikum Lake

In this study, actinobacteria isolated from Sarikum Lake sediment were characterized (Sinop-Turkey). A total of 48 actinobacteria were isolated using ten selective media with the dilution-plating method. The phylogenetic analysis according to 16S rRNA gene sequencing showed that 40% of the isolated strains belong to the widely distributed genus of Streptomyces, 36% belong to genus of Micromonospora, 24% of the isolates belong to rare genera such as Rhodococcus, Plantactinospora, Nonomuraea, Actinomadura and Streptosporangium. Most of the isolated strains belong to the genus Streptomyces (40%) and two isolates may be new species. All of the isolates were tested for antimicrobial activity; only 12 isolates exhibited antimicrobial activity. Nevertheless, 11 isolates were active against gram-positive, 5 were potential against gram-negative and no isolates had any effect against pathogenic fungi. All of the 48 isolates were analysed for genes encoding nonribosomal peptide synthetases (NRPS) and polyketide synthases (PKS). In all of the 48 isolates were detected NRPS sequences, PKS-I in 28 isolates and PKS-II in 22 isolates. PKS-I - PKS-II - NRPS genes were identified in 17 isolates.