1. Reservoir sediments are subjected to highly variable hydrostatic pressures, but little is known about the direct impacts of this environmental variable on microbial communities and biogeochemical processes mediated by microbes in the numerous deep reservoirs (>100 m) scattered across our planet.
2. To address this gap, the organic matter degradation and community assembly of sediment bacteria were studied in bioreactors maintained under different hydrostatic pressures (0.5–3.0 MPa) and explored using 16S rRNA amplicon sequencing analysis.
3. Our results showed that rates of CO₂ and CH₄ production and microbial activity decreased significantly with increasing pressure, at least when exceeding 1.0 MPa. In contrast, α‐diversity and community structure of the active (16S rRNA) and total (16S rRNA gene) bacterial communities did not show any significant response to the different hydrostatic pressures, but a co‐occurrence network demonstrated that interactions between bacterial populations were stronger at higher pressures (≥1.5 MPa).
4. Moreover, ecological null model analyses revealed that when the pressure exceeded 1.5 MPa, the main assembly processes of bacterial communities changed from stochastic to deterministic. These findings corroborate an important role of pressure in the assembly and emerging interactions within sediment bacterial communities.
5. Our results imply that increased hydrostatic pressure caused by dam constructions may hamper the metabolism of the sediment microbiota, and that this may result in enhanced sediment burial of nutrients and organic matter, at least when pressures exceed 1.0 MPa.

中文翻译：

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静水压力影响储层沉积物中细菌群落的活动和聚集

1. 油藏的沉积物承受着高度可变的静水压力，但是对于这种环境变量对分布在我们星球上的众多深层油藏（> 100 m）中微生物介导的微生物群落和生物地球化学过程的直接影响知之甚少。
2. 为了弥补这一差距，我们在维持不同静水压力（0.5-3.0 MPa）的生物反应器中研究了沉积物细菌的有机物降解和群落组装，并使用16S rRNA扩增子测序分析进行了研究。
3. 我们的结果表明，至少在超过1.0 MPa时，CO ₂和CH _4的产生速率以及微生物活性随压力的增加而显着降低。相比之下，活性细菌群落（16S rRNA）和总细菌群落（16S rRNA基因）的α-多样性和群落结构对不同的静水压力没有表现出明显的反应，但是共现网络表明细菌种群之间的相互作用是在较高压力（≥1.5MPa）下强度更高。
4. 此外，生态零模型分析表明，当压力超过1.5 MPa时，细菌群落的主要装配过程从随机变为确定性。这些发现证实了压力在沉积物细菌群落中的组装和新出现的相互作用中的重要作用。
5. 我们的结果表明，由大坝建造引起的静水压力增加可能会阻碍沉积物微生物的代谢，并且至少在压力超过1.0 MPa时，这可能会导致营养物和有机质的沉积物埋藏增加。