Formerly at Univ Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale de Lyon, Ampère, UMR5005, 69134, Ecully Cedex, France.
Currently at Interface Geochemistry, German Research Center for Geosciences, GFZ, Potsdam, Germany.
Microbiome. 2023 Mar 2;11(1):35. doi: 10.1186/s40168-023-01473-6.
Arctic snowpack microbial communities are continually subject to dynamic chemical and microbial input from the atmosphere. As such, the factors that contribute to structuring their microbial communities are complex and have yet to be completely resolved. These snowpack communities can be used to evaluate whether they fit niche-based or neutral assembly theories.
We sampled snow from 22 glacier sites on 7 glaciers across Svalbard in April during the maximum snow accumulation period and prior to the melt period to evaluate the factors that drive snowpack metataxonomy. These snowpacks were seasonal, accumulating in early winter on bare ice and firn and completely melting out in autumn. Using a Bayesian fitting strategy to evaluate Hubbell's Unified Neutral Theory of Biodiversity at multiple sites, we tested for neutrality and defined immigration rates at different taxonomic levels. Bacterial abundance and diversity were measured and the amount of potential ice-nucleating bacteria was calculated. The chemical composition (anions, cations, organic acids) and particulate impurity load (elemental and organic carbon) of the winter and spring snowpack were also characterized. We used these data in addition to geographical information to assess possible niche-based effects on snow microbial communities using multivariate and variable partitioning analysis.
While certain taxonomic signals were found to fit the neutral assembly model, clear evidence of niche-based selection was observed at most sites. Inorganic chemistry was not linked directly to diversity, but helped to identify predominant colonization sources and predict microbial abundance, which was tightly linked to sea spray. Organic acids were the most significant predictors of microbial diversity. At low organic acid concentrations, the snow microbial structure represented the seeding community closely, and evolved away from it at higher organic acid concentrations, with concomitant increases in bacterial numbers.
These results indicate that environmental selection plays a significant role in structuring snow microbial communities and that future studies should focus on activity and growth. Video Abstract.
北极积雪微生物群落不断受到来自大气的动态化学和微生物输入的影响。因此，影响其微生物群落结构的因素是复杂的，尚未完全解决。这些积雪群落可用于评估它们是否符合基于生态位或中性组装的理论。
我们在 4 月最大积雪期和融雪期之前，从斯瓦尔巴群岛 7 座冰川的 22 个冰川地点采集了积雪样本，以评估驱动积雪元分类学的因素。这些积雪是季节性的，在初冬时在裸露的冰和雪冰上积累，到秋季完全融化。我们使用贝叶斯拟合策略来评估在多个地点的 Hubbell 统一中性生物多样性理论，以检验中性和定义不同分类学水平的移民率。测量了细菌丰度和多样性，并计算了潜在冰核细菌的数量。还对冬季和春季积雪的化学成分（阴离子、阳离子、有机酸）和颗粒杂质负荷（元素和有机碳）进行了表征。我们使用这些数据以及地理信息，通过多元和变量划分分析，评估了基于生态位的因素对积雪微生物群落的可能影响。
虽然某些分类学信号与中性组装模型相符，但在大多数地点都观察到明显的基于生态位的选择证据。无机化学与多样性没有直接联系，但有助于识别主要的定植来源并预测微生物丰度，而微生物丰度与海雾密切相关。有机酸是微生物多样性的最重要预测因子。在低有机酸浓度下，雪微生物结构与播种群落密切相关，而在较高的有机酸浓度下，它会远离播种群落，同时细菌数量增加。
这些结果表明，环境选择在塑造积雪微生物群落结构方面起着重要作用，未来的研究应侧重于活性和生长。
