Abundances of the 16S rRNA gene and bacterial and archaeal amoA genes (gene copies g−1) in cryoconite on Aldegondabreen (mean ± sd; n = 3)

Table 4. Abundances of the 16S rRNA gene and bacterial and archaeal amoA genes (gene copies g−1) in cryoconite on Aldegondabreen (mean ± sd; n = 3). b.d. below detection limit. Abstract The aggregation of surface debris particles on melting glaciers into larger units (cryoconite) provides microenvironments for various microorganisms and metabolic processes. Here we investigate the microbial community on the surface of Aldegondabreen, a valley glacier in Svalbard which is supplied with carbon and nutrients from different sources across its surface, including colonies of seabirds. We used a combination of geochemical analysis (of surface debris, ice and meltwater), quantitative polymerase chain reactions (targeting the 16S ribosomal ribonucleic acid and amoA genes), pyrosequencing and multivariate statistical analysis to suggest possible factors driving the ecology of prokaryotic microbes on the surface of Aldegondabreen and their potential role in nitrogen cycling. The combination of high nutrient input with subsidy from the bird colonies, supraglacial meltwater flow and the presence of fine, clay-like particles supports the formation of centimetre-scale cryoconite aggregates in some areas of the glacier surface. We show that a diverse microbial community is present, dominated by the cyanobacteria, Proteobacteria, Bacteroidetes, and Actinobacteria, that are well-known in supraglacial environments. Importantly, ammonia-oxidizing archaea were detected in the aggregates for the first time on an Arctic glacier.

表4. 奥尔德贡达冰川（Aldegondabreen）冰尘（cryoconite）中16S核糖体RNA基因（16S rRNA gene）、细菌及古菌氨单加氧酶A亚基基因（amoA gene）的丰度（基因拷贝数·g⁻¹；均值±标准差，n=3）。b.d. 表示低于检测限。

摘要：融化冰川表面的碎屑颗粒聚集形成更大的团聚体（冰尘，cryoconite），可为各类微生物及代谢过程提供微生境。本研究以斯瓦尔巴群岛的山谷冰川奥尔德贡达冰川（Aldegondabreen）为研究对象，该冰川表面各处存在包括海鸟群落在内的多种碳与营养物质输入源。研究团队结合表面碎屑、冰川冰与融水的地球化学分析、靶向16S核糖体RNA及amoA基因的定量聚合酶链式反应、焦磷酸测序与多元统计分析，探究了奥尔德贡达冰川表面原核微生物群落的驱动因子及其在氮循环中的潜在作用。高营养输入结合海鸟群落的养分补给、冰面融水径流以及细颗粒黏土状物质的存在，共同促成了冰川表面部分区域形成厘米级的冰尘团聚体。研究发现该区域存在多样的微生物群落，优势类群为冰面环境中常见的蓝细菌门（Cyanobacteria）、变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）与放线菌门（Actinobacteria）。尤为重要的是，本研究首次在北极冰川的冰尘团聚体中检测到氨氧化古菌。