青藏高原阿里、那曲和海西地区土壤可培养放线菌的多样性

【目的】为了研究青藏高原北部地区土壤可培养放线菌的多样性,并比较不同选择性分离培养基对高原土壤放线菌的分离效果。【方法】使用9种分离培养基,并尝试添加藤黄微球菌发酵液,对采集自阿里、那曲和海西地区的14份土壤样品中的放线菌进行选择性分离。通过16S r RNA基因序列分析对分离菌株进行初步分类鉴定,并在不同分类水平上统计所分离得到的放线菌多样性。【结果】分离得到去重复后的放线菌255株,分布于放线菌门的8个目,14个科,23个属,包含94个可能的物种。其中至少25个物种可能为新种,分布于13个属。链霉菌属的菌株108株,可能的物种28个,是最主要的优势菌属。分离培养基中添加藤黄微球菌发酵液明显增加了放线菌分离菌株的数量和多样性,稀释的葡萄糖酵母麦芽汁培养基适合分离链霉菌,淀粉甘油脯氨酸培养基、丙酸钠酪蛋白培养基等则适合分离稀有放线菌。【结论】青藏高原北部土壤放线菌多样性非常丰富,并且存在较多的新颖放线菌类群;添加藤黄微球菌发酵液是提高放线菌分离效率的有效手段。

Diversity of culturable actinobacteria from soils collected in Ali, Naqu and Haixi Districts on the Qinghai-Tibet Plateau

Objective] This study is aimed at studying the diversity of culturable actinobacteria in soils of the north Qinghai-Tibet Plateau and comparing the effect of different selective isolation media on the isolation of actinobacteria.Methods] We used 9 isolation media to isolate actinobacteria from 14 soil samples collected from Ali, Naqu and Haixi districts on the Qinghai-Tibet Plateau. We added the fermentation broth of Micrococcus luteus to the medium to help the isolation. The isolates were identified based on the 16S rRNA gene sequences, and diversity of actinobacterial isolates were analyzed at different taxonomic levels.Results] We isolated a total of 255 dereplicated strains, belonging to 8 orders, 14 families and 23 genera of the phylum Actinobacteria. The isolates were delineated into 94 OTUs, which corresponded to 94 putative species. Among them, at least 25 putative species were new, spanning 13 genera; and 108 strains, which contained 28 putative species, belonged to the genus Streptomyces, the most dominant genus of culturable actinobacteria from the soils. Addition of the Micrococcus luteus fermentation broth obviously increased the number and diversity of actinobacterial isolates. Diluted glucose-yeast extract-malt extract medium was suitable for the isolation of Streptomyces, and starch-glycerol-proline medium, sodium propionate-casein medium, etc. were suitable for the isolation of rare actinobacteria.Conclusion] Soils of the north Qinghai-Tibet Plateau contain a high diversity of culturable actinobacteria and a number of novel actinobacterial species. Addition of the Micrococcus lutea fermentation broth into the isolation medium can effectively improve the isolation efficiency for actinobacteria.