Diversity and potential sources of microbiota associated with snow on western portions of the Greenland Ice Sheet

Snow overlays the majority of the Greenland Ice Sheet (GrIS). However, there is very little information available on the microbiological assemblages that are associated with this vast and climate-sensitive landscape. In this study, the structure and diversity of snow microbial assemblages from two regions of the western GrIS ice margin were investigated through the sequencing of small subunit ribosomal RNA genes. The origins of the microbiota were investigated by examining correlations to molecular data obtained from marine, soil, freshwater and atmospheric environments and geochemical analytes measured in the snow. Snow was found to contain a diverse assemblage of bacteria (Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria) and eukarya (Alveolata, Fungi, Stramenopiles and Chloroplastida). Phylotypes related to archaeal Thaumarchaeota and Euryarchaeota phyla were also identified. The snow microbial assemblages were more similar to communities characterized in soil than to those documented in marine ecosystems. Despite this, the chemical composition of snow samples was consistent with a marine contribution, and strong correlations existed between bacterial beta diversity and the concentration of Na+ and Cl-. These results suggest that surface snow from western regions of Greenland contains exogenous microbiota that were likely aerosolized from more distant soil sources, transported in the atmosphere and co-precipitated with the snow. Citation: Karen A. Cameron, Birgit Hagedorn, Markus Dieser, Ronald Sletten, Byron Crump, Colleen Kellogg and Karen Junge (2014), Diversity and potential sources of microbiota associated with snow on western portions of the Greenland Ice Sheet, Environ. Microbiol., doi:10.1111/1462-2920.12446.

格陵兰冰盖（Greenland Ice Sheet, GrIS）的绝大部分区域被积雪覆盖，但针对这片广袤且对气候变化敏感的景观相关的微生物群落的研究资料却极为匮乏。本研究通过对小型亚基核糖体RNA基因（small subunit ribosomal RNA genes）进行测序，探究了格陵兰冰盖西部冰缘两个区域的积雪微生物群落的结构与多样性。研究人员通过比对海洋、土壤、淡水与大气环境中获得的分子数据与积雪中测得的地球化学分析物的相关性，以此追溯该微生物群的来源。研究发现，积雪中包含多样的细菌类群（α-变形菌门（Alphaproteobacteria）、β-变形菌门（Betaproteobacteria）与γ-变形菌门（Gammaproteobacteria））以及真核生物类群（囊泡虫类（Alveolata）、真菌（Fungi）、不等鞭毛类（Stramenopiles）与绿色植物界（Chloroplastida））。本研究还鉴定出了属于古菌奇古菌门（Thaumarchaeota）和广古菌门（Euryarchaeota）的系统发育型。积雪微生物群落与土壤群落的相似性要高于海洋生态系统中已记录的群落。尽管如此，积雪样本的化学成分却显示出海洋来源的贡献，且细菌β多样性与Na+和Cl-的浓度存在显著相关性。上述结果表明，格陵兰西部区域的表层积雪中存在外源微生物群，这些微生物大概率来自更远端的土壤源，经大气气溶胶化后传输，并随降雪共同沉降。引用：Karen A. Cameron、Birgit Hagedorn、Markus Dieser、Ronald Sletten、Byron Crump、Colleen Kellogg与Karen Junge（2014），《格陵兰冰盖西部积雪相关微生物群的多样性与潜在来源》，《Environ. Microbiol.》，doi:10.1111/1462-2920.12446。