Li Ke, Bai Zhihui, Zhang Hongxun
University of Chinese Academy of Sciences, Beijing, 100049, China.
Extremophiles. 2015 Jan;19(1):171-81. doi: 10.1007/s00792-014-0696-z. Epub 2014 Sep 25.
Pyrosequencing and quantitative polymerase chain reaction of small subunit rRNA genes were used to provide a comprehensive examination of bacterial, cyanobacterial, and eukaryotic communities in the biological soil crusts (BSCs) of Gurbantünggüt Desert sand dunes (China). Three succession stages were recognized based on the analyses of eukaryotic communities: a late succession stage of BSCs in a swale with eukaryotes mainly related to the Bryophyta clade, an initial succession stage in a slope with barely any eukaryotic phototrophic microorganisms detected, and an intermediate succession type detected from both the swale and slope BSCs dominated by the phylum Chlorophyta. Moreover, the cyanobacterial community dominated all of the BSCs (48.2-69.5% of the total bacteria) and differed among the three succession stages: sequences related to Microcoleus steenstrupii and the genus Scytonema were abundant in the later succession stage, whereas both the initial and intermediate stages were dominated by Microcoleus vaginatus. Compared with swales, BSCs from slopes are exposed to a harsher environment, e.g., higher irradiance and lower water availability, and thus may be restricted from developing to a higher succession stage. Other disturbances such as wind and grazing may explain the different succession stages observed in swales or slopes. However, no clear differences were detected from non-phototrophic bacterial communities of the three succession stages, and sequences related to Alphaproteobacteria and Actinobacteria were most abundant in all the BSCs. The closest matches for the most frequent non-phototrophic bacterial genera were mainly derived from harsh environments, indicating the robustness of these genera.
采用焦磷酸测序和小亚基rRNA基因定量聚合酶链反应，对中国古尔班通古特沙漠沙丘生物土壤结皮（BSCs）中的细菌、蓝细菌和真核生物群落进行了全面检测。基于真核生物群落分析，识别出三个演替阶段：洼地中生物土壤结皮的晚期演替阶段，其中真核生物主要与苔藓植物进化枝相关；斜坡上的初始演替阶段，几乎未检测到任何真核光合微生物；以及在洼地和斜坡生物土壤结皮中均检测到的以绿藻门为主的中间演替类型。此外，蓝细菌群落主导了所有生物土壤结皮（占细菌总数的48.2%-69.5%），且在三个演替阶段有所不同：与斯氏鞘丝藻和伪枝藻属相关的序列在晚期演替阶段丰富，而初始阶段和中间阶段均以鞘丝藻为主。与洼地相比，斜坡上的生物土壤结皮暴露于更恶劣的环境中，例如更高的光照强度和更低的水分可利用性，因此可能受到限制而无法发展到更高的演替阶段。其他干扰因素，如风蚀和放牧，可能解释了洼地或斜坡上观察到的不同演替阶段。然而，在三个演替阶段的非光合细菌群落中未检测到明显差异，且与变形菌门和放线菌门相关的序列在所有生物土壤结皮中最为丰富。最常见的非光合细菌属的最相似匹配序列主要来自恶劣环境，表明这些属具有较强的适应性。
