Franzetti Andrea, Navarra Federico, Tagliaferri Ilario, Gandolfi Isabella, Bestetti Giuseppina, Minora Umberto, Azzoni Roberto Sergio, Diolaiuti Guglielmina, Smiraglia Claudio, Ambrosini Roberto
Dept. of Earth and Environmental Sciences (DISAT) - University of Milano-Bicocca, Milano, Italy.
"A. Desio" Dept. of Earth Sciences, Università degli Studi di Milano, Milano, Italy.
PLoS One. 2017 Mar 30;12(3):e0174786. doi: 10.1371/journal.pone.0174786. eCollection 2017.
We investigated the potential contribution of ice-marginal environments to the microbial communities of cryoconite holes, small depressions filled with meltwater that form on the surface of Forni Glacier (Italian Alps). Cryoconite holes are considered the most biologically active environments on glaciers. Bacteria can colonize these environments by short-range transport from ice-marginal environments or by long-range transport from distant areas. We used high throughput DNA sequencing to identify Operational Taxonomic Units (OTUs) present in cryoconite holes and three ice-marginal environments, the moraines, the glacier forefield, and a large (> 3 m high) ice-cored dirt cone occurring on the glacier surface. Bacterial communities of cryoconite holes were different from those of ice-marginal environments and hosted fewer OTUs. However, a network analysis revealed that the cryoconite holes shared more OTUs with the moraines and the dirt cone than with the glacier forefield. Ice-marginal environments may therefore act as sources of bacteria for cryoconite holes, but differences in environmental conditions limit the number of bacterial strains that may survive in them. At the same time, cryoconite holes host a few OTUs that were not found in any ice-marginal environment we sampled, thus suggesting that some bacterial populations are positively selected by the specific environmental conditions of the cryoconite holes.
我们研究了冰缘环境对冰尘穴微生物群落的潜在贡献，冰尘穴是福尔尼冰川（意大利阿尔卑斯山）表面形成的充满融水的小洼地。冰尘穴被认为是冰川上生物活性最强的环境。细菌可以通过从冰缘环境的短距离传输或从遥远地区的长距离传输在这些环境中定殖。我们使用高通量DNA测序来识别冰尘穴和三种冰缘环境中存在的操作分类单元（OTU），这三种冰缘环境分别是冰碛、冰川前缘以及冰川表面出现的一个大型（> 3米高）的冰核土锥。冰尘穴的细菌群落与冰缘环境的不同，且包含的OTU较少。然而，网络分析表明，冰尘穴与冰碛和土锥共享的OTU比与冰川前缘共享的更多。因此，冰缘环境可能是冰尘穴细菌的来源，但环境条件的差异限制了可能在其中存活的细菌菌株数量。与此同时，冰尘穴中存在一些我们在任何采样的冰缘环境中都未发现的OTU，这表明一些细菌种群受到冰尘穴特定环境条件的正向选择。
