Microbes in the atmosphere have broad ecological impacts, including the potential to trigger precipitation through species and strains that act as ice nucleation particles. To characterize spatiotemporal trends of microbial assemblages in precipitation we sequenced 16S (bacterial) and 18S (fungal) rRNA gene amplicon libraries collected from 72 precipitation events in three U.S. states (Idaho, Louisiana, and Virginia) over four seasons. We considered these data from the perspective of a novel metacommunity framework. In agreement with our heuristic, we found evidence for distinct mechanisms underlying the composition and diversity of bacterial and fungal assemblages in precipitation. Specifically, we determined that (1) bacterial operational taxonomic unit (OTU) composition of precipitation was strongly associated with macroscale drivers including season and high‐altitude characteristics of storms; (2) fungal OTU composition was strongly correlated with mesoscale drivers including particular spatial locations; (3) β‐diversity (heterogeneity of taxa among samples) for both bacteria and fungi was largely maintained by turnover of taxa; however, (4) bacterial assemblages had higher contributions to total β‐diversity from nestedness (i.e., lower richness assemblages were largely taxonomic subsets of richer assemblages), due to losses of taxa during dispersal, particularly among potential ice nucleation active bacteria; and (5) fungal assemblages had higher contributions to total β‐diversity from turnover due to OTU replacement. Spatiotemporal trends in precipitation‐borne metacommunities allowed delineation of a large number of statistically significant indicator taxa for particular sites and seasons, including trends for bacteria that are potentially ice nucleation active. Our findings advance understanding regarding the dispersion of aerosolized microbes via wet deposition, and the development of theory concerning potential assembly rules for bioaerosol assemblages.

中文翻译：

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微生物组成的时空格局和降水的多样性

大气中的微生物具有广泛的生态影响，包括通过充当冰核颗粒的物种和菌株触发降水的潜力。为了表征降水中微生物组合的时空趋势，我们对四个季节从美国三个州（爱达荷州，路易斯安那州和弗吉尼亚州）的72次降水事件中收集到的16S（细菌）和18S（真菌）rRNA基因扩增子文库进行了测序。我们从新颖的元社区框架的角度考虑了这些数据。与我们的启发式方法一致，我们发现了沉淀中细菌和真菌组合物的组成和多样性的不同机制的证据。具体来说，我们确定（1）降水的细菌操作分类单位（OTU）组成与宏观驱动因素密切相关，包括风暴的季节和高空特征；（2）真菌OTU的组成与中尺度驱动力密切相关，包括特定的空间位置；（3）细菌和真菌的β多样性（样品中分类单元的异质性）在很大程度上是通过分类单元的转换来维持的；但是，（4）细菌组合对巢中总β-多样性的贡献更大（即，较低的丰富度组合主要是较丰富的组合的分类学子集），这是由于散布期间的类群损失，尤其是在潜在的冰核活性细菌中。（5）真菌组合对总β的贡献更大 （2）真菌的OTU组成与中尺度驱动力密切相关，包括特定的空间位置；（3）细菌和真菌的β多样性（样品中分类单元的异质性）在很大程度上是通过分类单元的转换来维持的；但是，（4）细菌组合对巢中总β-多样性的贡献更大（即，较低的丰富度组合主要是较丰富的组合的分类学子集），这是由于散布期间的类群损失，尤其是在潜在的冰核活性细菌中。（5）真菌组合对总β的贡献更大 （2）真菌OTU的组成与中尺度驱动力密切相关，包括特定的空间位置；（3）细菌和真菌的β多样性（样品中分类单元的异质性）在很大程度上是通过分类单元的转换来维持的；但是，（4）细菌组合对巢中总β-多样性的贡献更大（即，较低的丰富度组合主要是较丰富的组合的分类学子集），这是由于散布期间的类群损失，尤其是在潜在的冰核活性细菌中。（5）真菌组合对总β的贡献更大 （4）由于散布过程中类群的损失，特别是在潜在的冰核成活细菌中，细菌的聚集对巢中总β多样性的贡献更大（即，较低的富集在很大程度上是较富集的分类学子集）；（5）真菌组合对总β的贡献更大 （4）由于散布过程中类群的损失，特别是在潜在的冰核成活细菌中，细菌的聚集对巢中总β多样性的贡献更大（即，较低的富集在很大程度上是较富集的分类学子集）；（5）真菌组合对总β的贡献更大-由于更换了OTU，营业额的多样性。降水传播的元社区的时空趋势允许描述特定地点和季节的大量具有统计意义的指示性分类单元，包括可能具有冰核活性的细菌的趋势。我们的发现提高了对通过湿式沉积雾化微生物扩散的理解，以及有关生物气雾剂组装潜在组装规则的理论的发展。