Phylogenetic diversity and biological activities of marine actinomycetes isolated from sediments of the Yellow Sea Cold Water Mass, China

AbstractIn China's Yellow Sea Cold Water Mass (YSCWM), the unique environmental conditions (e.g. low temperature, high salinity and large temperature gradient) may support the growth of novel microbial populations with specific biological activities. In this study, 172 isolates of marine actinomycetes were obtained from 20 sediment samples of the YSCWM. Based on phylogenetic analysis of 16S rRNA genes, the actinomycete isolates were classified into five actinobacterial taxa. Members of Streptomyces were widely dominant (63.3%) while those of Nocardiopsis, Actinoalloteichus, Micromonospora and a novel genus Spinactinospora accounted for smaller proportions (19.1%, 8.7%, 7.6% and 1.2%, respectively). Of the 172 actinomycete isolates, 33.7% exhibited antibacterial activity against at least one of the four human pathogens tested (Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Edwardsiella tarda), whereas 65.1–93.6% were capable of producing exoenzymes (lipase, caseinase and amylase). The large...