Freshwater ecosystems are under increasing threat of salinization due to human activity. Given the contributions of microbial communities to stream ecosystems, it is critical to understand how these communities are affected by the increasing presence of salt in the environment. We used an artificial stream system to investigate how salt concentrations representing the 95th- and 99th-percentile of concentrations observed in NE Ohio streams affect bacterial community succession and what implications this has on community-level functional capabilities. We hypothesized that the successional trajectory of community functionality (in the form of extracellular enzyme activity) and structure (via denitrification gene abundances and community 16S rRNA gene profiles) would be altered in response to increasing salt concentrations. We observed considerable structural changes in bacterial composition among treatments that corresponded with niche expansion by more salt-tolerant taxa. Increases in denitrification gene abundances and modifications to extracellular enzyme activity were also observed. These data suggest that continued salt pollution can dramatically affect community structure and has the potential to modify the functional contributions of the bacterial community to the ecosystem.

中文翻译：

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急性盐胁迫促进新生淡水微生物生物膜组装动力学的改变

由于人类活动，淡水生态系统正面临越来越大的盐碱化威胁。鉴于微生物群落对河流生态系统的贡献，了解这些群落如何受到环境中盐分增加的影响至关重要。我们使用人工流系统来研究代表在俄亥俄州东北部河流中观察到的浓度的第 95 和 99 百分位的盐浓度如何影响细菌群落演替，以及这对群落水平功能能力的影响。我们假设群落功能（以细胞外酶活性的形式）和结构（通过反硝化基因丰度和群落 16S rRNA 基因谱）的连续轨迹将随着盐浓度的增加而改变。我们观察到与更耐盐类群的生态位扩张相对应的处理中细菌组成的显着结构变化。还观察到反硝化基因丰度的增加和胞外酶活性的改变。这些数据表明，持续的盐污染会显着影响群落结构，并有可能改变细菌群落对生态系统的功能贡献。