浑善达克沙地夏冬季浅色型生物土壤结皮中古菌的系统发育多样性

【目的】生物土壤结皮(Biological soil crusts,BSCs)对于遏制土壤荒漠化、恢复荒漠地区生态环境起着重要作用。BSCs形成和发展的关键角色是微生物。但关于BSCs中微生物组成的认识还不够全面和系统,特别是对其中的古菌鲜有研究报道。【方法】通过构建和分析古菌16S rRNA基因克隆文库,揭示浑善达克沙地BSCs中古菌多样性和系统发育类型组成,并比较它们夏季和冬季的变化。【结果】BSCs样品颜色为褐色,厚度较薄,所含氮和磷营养养分不高;8月份和11月份的BSCs古菌16S rRNA基因文库覆盖度均达95%以上,代表性强;两个文库共得到可用的142条古菌16S rRNA基因序列,以0.03为Cutoff值、这些序列分入10个OTUs中,两个季节的最优势种群相同;8月份和11月份的古菌均属于奇古菌门,但群落结构存在很大的不同,即各自所独有的种群分别有1个和4个;BSCs中古菌多样性均不高,但11月份的明显高于8月份的。【结论】温带沙地浅色型BSCs中古菌的主要为奇古菌、多样性低,其群落结构随季节变换而有较大变化。本研究为系统认识BSCs古菌的多样性及其生态作用提供了基础。

Summer and winter phylogenetic diversity of Archaea in light-color type soil crusts from Desert Hunsandake

Objective] Biological soil crusts (BSCs) play an important role in restoring the ecological environment and constraining soil desertification. Microorganisms are important in the development of BSCs. However, the investigation on the microbial composition of BSCs is still limited now, especially is rare about archaea. Methods] We constructed and analyzed archaeal 16S rRNA gene library to discover the diversity and phylotype composition of BSCs archaea from Desert Hunsandake, compared the variation between summer and winter. Results] BSC samples were thin and brown with low levels of nitrogen and phosphate nutrients. The coverages of both libraries of August and November were over 95% and strongly representative. In total 142 archaeal 16S rRNA sequences were obtained from the two libraries and these sequences were divided into 10 operational taxonomic units (OTUs) with the cutoff value of 0.03. In both libraries the predominant OTU was the same, probably a unique group in desert. All sequences obtained from this study were originated from members of Thaumarchaeota, the third phylum of Archaea, but a large difference in community structure was observed between the two libraries of August and November. Only one unique OTU was found in August and four in November. Archaeal diversity in BSCs is low and yet the diversity of November was higher than that of August. Conclusion] Archaea in light-colored BSCs from temperate desert is dominated by the Thaumarchaeota species with lower diversity and the community structure largely varies with season changing.