Biodiversity and antimicrobial activities of culturable actinomycetes isolated from the soil of Dabancheng Salt Lake, Xinjiang, China

Abstract:

[Background] In recent years, new strains of actinomycetes have been discovered in the saline-alkali environments such as Ebinur Lake, Qijiaojing Salt Lake, and Lop Nur in Xinjiang of China. However, there are few reports about the actinomycetes strains isolated from the soil of Dabancheng Salt Lake. [Objective] We studied the diversity of culturable actinomycetes in the soil of Dabancheng Salt Lake in Xinjiang and screened out the strains with activities of functional enzymes, aiming to mine new medicinal microbial resources and lay a foundation for the discovery of new antibiotics. [Methods] The diversity of culturable actinomycetes in the soil of Dabancheng Salt Lake was investigated by the culture-dependent method and the phylogenetic analysis based on 16S rRNA gene sequences. PCR was employed to explore the distribution of the genes encoding types I and II polyketide synthase (pksI and pskII), non-ribosomal peptide synthase (nrps), and aminoglycoside phosphotransferase (aph) for antibiotic synthesis. The agar diffusion method was employed to screen the strains with antimicrobial activities and the strains capable of producing functional enzymes (with nine substrates as indicators). [Results] A total of 65 actinomycetes strains belonging to nine genera, five families of five orders were isolated from fourteen soil samples of Dabancheng Salt Lake. Streptomyces and Nocardiopsis were the dominant genera and two strains were potential new species. Abundant genes involved in antibiotic synthesis were identified. A strain (D21E05) with antagonistic effects on Gram-positive, Gram-negative, and fungi was screened out. The soil of Dabancheng Salt Lake harbored rich strains producing protease, lipase, catalase, cellulase, and amylase. [Conclusion] The soil of Dabancheng Salt Lake harbors rich medicinal actinomycetes resources, from which new actinomycetes species and new antibiotics can be discovered.