Press disturbances are of interest in microbial ecology, as they can drive microbial communities to alternative stable states. However, the effect of press disturbances in community assembly mechanisms, particularly with regard to taxa and functional genes at different levels of abundance (i.e., common and rare), remains largely unknown. Here, we tested the effect of a continuous alteration in substrate feeding scheme on the structure, function, and assembly of bacterial communities. Two sets of replicate 5-liter sequencing batch reactors were operated at two different organic carbon loads for a period of 74 days, following 53 days of acclimation after inoculation with sludge from a full-scale treatment plant. Temporal dynamics of community taxonomic and functional gene structure were derived from metagenomics and 16S rRNA gene metabarcoding data. Disturbed reactors exhibited different community function, structure, and assembly compared to undisturbed reactors. Bacterial taxa and functional genes showed dissimilar α-diversity and community assembly patterns. Deterministic assembly mechanisms were generally stronger in disturbed reactors and in common fractions compared to rare ones. Function quickly recovered after the disturbance was removed, but community structure did not. Our results highlight that functional gene data from metagenomics can indicate patterns of community assembly that differ from those obtained from taxon data. This study reveals how a joint evaluation of assembly mechanisms and community structure of bacterial taxa and functional genes as well as ecosystem function can unravel the response of complex microbial systems to a press disturbance.

中文翻译：

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压力干扰改变了中宇宙规模生物反应器中细菌类群和功能基因的群落结构和组装机制。

压力扰动在微生物生态学中很有趣，因为它们可以促使微生物群落达到替代的稳定状态。然而，压力干扰对群落组装机制的影响，特别是对于不同丰度水平（即常见和稀有）的类群和功能基因的影响，仍然很大程度上未知。在这里，我们测试了连续改变底物喂养方案对细菌群落的结构、功能和组装的影响。两组复制的 5 升序批式反应器在接种全规模处理厂的污泥后经过 53 天的适应，在两种不同的有机碳负荷下运行 74 天。群落分类和功能基因结构的时间动态源自宏基因组学和 16S rRNA 基因宏条形码数据。与未扰动的反应堆相比，扰动的反应堆表现出不同的群落功能、结构和组装。细菌类群和功能基因表现出不同的α多样性和群落组装模式。与稀有反应堆相比，确定性组装机制在受干扰的反应堆和常见分数中通常更强。干扰消除后功能很快恢复，但群落结构却没有。我们的结果强调，来自宏基因组学的功能基因数据可以表明与从分类单元数据获得的群落组装模式不同的模式。这项研究揭示了对细菌类群和功能基因的组装机制和群落结构以及生态系统功能的联合评估如何能够揭示复杂微生物系统对压力干扰的响应。