Section of Microbial Ecology - MEMEG, Department of Biology, Lund University, Lund, Sweden.
Centre for Environmental and Climate Research (CEC), Lund University, Lund, Sweden.
mBio. 2019 Jul 23;10(4):e01607-19. doi: 10.1128/mBio.01607-19.
The structure and function of microbial communities vary along environmental gradients; however, interlinking the two has been challenging. In this study, salinity was used as an environmental filter to study how it could shape trait distributions, community structures, and the resulting functions of soil microbes. The environmental filter was applied by salinizing nonsaline soil (0 to 22 mg NaCl g). Our targeted community trait distribution (salt tolerance) was determined with dose-response relationships between bacterial growth and salinity. The bacterial community structure responses were resolved with Illumina 16S rRNA gene amplicon sequencing, and the microbial functions determined were respiration and bacterial and fungal growth. Salt exposure quickly resulted in filtered trait distributions, and stronger filters resulted in larger shifts. The filtered trait distributions correlated well with community composition differences, suggesting that trait distribution shifts were driven at least partly by species turnover. While salt exposure decreased respiration, microbial growth responses appeared to be characterized by competitive interactions. Fungal growth was highest when bacterial growth was inhibited by the highest salinity, and it was lowest when the bacterial growth rate peaked at intermediate salt levels. These findings corroborated a higher potential for fungal salt tolerance than bacterial salt tolerance for communities derived from a nonsaline soil. In conclusion, by using salt as an environmental filter, we could interlink the targeted trait distribution with both the community structure and resulting functions of soil microbes. Understanding the role of ecological communities in maintaining multiple ecosystem processes is a central challenge in ecology. Soil microbial communities perform vital ecosystem functions, such as the decomposition of organic matter to provide plant nutrition. However, despite the functional importance of soil microorganisms, attribution of ecosystem function to particular constituents of the microbial community has been impeded by a lack of information linking microbial processes to community composition and structure. Here, we apply a conceptual framework to determine how microbial communities influence ecosystem processes, by applying a "top-down" trait-based approach. By determining the dependence of microbial processes on environmental factors (e.g., the tolerance to salinity), we can define the aggregate response trait distribution of the community, which then can be linked to the community structure and the resulting function performed by the microbial community.
微生物群落的结构和功能沿环境梯度变化；然而，将两者联系起来一直具有挑战性。在这项研究中，盐分被用作环境过滤器，以研究它如何塑造特征分布、群落结构以及土壤微生物的功能。通过将非盐渍土（0 至 22mgNaCl/g）盐渍化来应用环境过滤器。我们的目标群落特征分布（盐度耐受性）是通过细菌生长与盐度之间的剂量反应关系来确定的。通过 Illumina 16S rRNA 基因扩增子测序来解决细菌群落结构的响应，并且确定的微生物功能是呼吸作用以及细菌和真菌的生长。盐暴露迅速导致特征分布过滤，而较强的过滤器导致更大的变化。过滤后的特征分布与群落组成差异密切相关，表明特征分布的变化至少部分是由物种更替驱动的。虽然盐暴露降低了呼吸作用，但微生物生长的响应似乎以竞争相互作用为特征。当最高盐度抑制细菌生长时，真菌生长最高，而当细菌生长速率在中间盐度水平达到峰值时，真菌生长最低。这些发现证实了源自非盐渍土壤的群落中真菌的盐度耐受性比细菌的盐度耐受性更高。总之，通过将盐用作环境过滤器，我们可以将目标特征分布与土壤微生物的群落结构和功能结果联系起来。理解生态群落在维持多种生态系统过程中的作用是生态学的一个核心挑战。土壤微生物群落执行重要的生态系统功能，例如分解有机物以提供植物营养。然而，尽管土壤微生物具有功能重要性，但将生态系统功能归因于微生物群落的特定组成部分受到将微生物过程与群落组成和结构联系起来的信息缺乏的阻碍。在这里，我们应用一个概念框架通过应用基于特征的“自上而下”方法来确定微生物群落如何影响生态系统过程。通过确定微生物过程对环境因素（例如，对盐分的耐受性）的依赖性，我们可以定义群落的综合响应特征分布，然后将其与群落结构和微生物群落执行的功能联系起来。
