Abstract:[Background] The extreme habitats of the Qinghai-Tibet Plateau (QTP) harbor rich microbial resources and are important sources of microbial drugs, with abundant microbial resources remaining to be exploited.[Objective] A Streptomyces strain Qhu-G9 isolated from Gobi soil of the QTP was identified by polyphasic taxonomy, and its biosynthesis potential of secondary metabolites was analyzed. [Methods] The taxonomic status of Streptomyces Qhu-G9 was determined by 16S rRNA gene amplification, sequencing, and phylogenetic analysis, combined with polyphasic taxonomy based on genome sequencing and morphological, physiochemical, and cytochemical characteristics. [Results] Qhu-G9 had the highest similarity (99.22%) with the type strains Streptomyces dioscori A217T and S. auranttⅡacus NBRC 13017T, which, combined with morphological characteristics, indicated that Qhu-G9 belonged to Streptomyces. However, the phylogenetic tree constructed based on the 16S rRNA gene sequence displayed that Qhu-G9 branched independently. Moreover, the physiochemical and cytochemical characteristics of this strain were quite different from those of the most similar model bacteria. We then employed genome sequencing to evaluate the digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) between Qhu-G9 and the model bacteria. The dDDH and ANI values were the highest between Qhu-G9 and S. auranttⅡacus NBRC 13017T, reaching 36.65% and 88.21%, respectively, both of which were lower than those determining a novel species. The results further confirmed that Qhu-G9 was a novel species of Streptomyces and named as S. haixigobicum sp. nov. Qhu-G9. In addition, antiSMASH revealed a large number of gene clusters for the biosynthesis of known and unknown secondary metabolites in the Qhu-G9 genome. [Conclusion] Qhu-G9 isolated from Gobi soil of the QTP is a novel Streptomyces species and has great potential for the production of active secondary metabolites.

Abstract:[Background] Lhalu Wetland was the highest and largest urban natural wetland in China. Studying on microbial community structure in Lhalu Wetland could provide theoretical basis for exploitation and protection of biological resources in Qinghai-Tibet plateau, and lay foundation for the study of microbial diversity in wetland ecosystem. [Objective] investigate diversity of mycelial fungus and explore the main environmental factors which influenced the community structure of filamentous fungi in Lhalu Wetland. [Methods] Fungi were isolated from 11 water samples, and identification of fungi were completed using the sequence analysis of nrDNA ITS, combining with traditional classified method. SPSS and CANOCO were used to examine correlations between filamentous fungi diversity and environmental factors. [Results] Mycelial fungi isolated from Lhalu Wetland were belonging to 6 genera and 13 species. Mucor, Cladosporium, Galactomyces were the dominate genera in the wetland. M. hiemalis、M. racemosus and G. geotrichum were the dominate species. Statistical analysis indicated that TN has significantly negative correlation with the counts of filamentous fungi at the Lhalu Wetland (P<0.05), moreover, TN and TP had significant effect on distribution of the fungi, which positively correlated with M. racemosus but passively correlated with M. hiemalis. [Conclusion] Environmental variable has been one of the major factors that influencing wetland microorganism community structure, therefore, it was crucial concerning to study the relationship between environmental factors and diversity of microbe in Tibet.