Biomethanation is a promising solution to upgrade the CH4 content in biogas. This process consists in the injection of H2 into an anaerobic digester, using the capacity of indigenous hydrogenotrophic methanogens for converting the injected H2 and the CO2 generated from the anaerobic digestion process into CH4. However, the injection of H2 could cause process disturbances by impacting the microbial communities of the anaerobic digester. Better understanding on how the indigenous microbial community can adapt to high H2 partial pressures is therefore required. Seven microbial inocula issued from industrial bioprocesses treating different types of waste were exposed to a high H2 partial pressure in semi-continuous reactors. After 12 days of operation, even though both CH4 and volatile fatty acids (VFA) were produced as end products, one of them was the main product. Acetate was the most abundant VFA, representing up to 94% of the total VFA production. VFA accumulation strongly anti-correlated with CH4 production according to the source of inoculum. Three clusters of inocula were distinguished: (1) inocula leading to CH4 production, (2) inocula leading to the production of methane and VFA in a low proportion, and (3) inocula leading to the accumulation of mostly VFA, mainly acetate. Interestingly, VFA accumulation was highly correlated to a low proportion of archaea in the inocula, a higher amount of homoacetogens than hydrogenotrophic methanogens and, the absence or the very low abundance in members from the Methanosarcinales order. The best methanogenic performances were obtained when hydrogenotrophic methanogens and Methanosarcina sp. co-dominated all along the operation. New insights on the microbial community response to high H2 partial pressure are provided in this work. H2 injection in semi-continuous reactors showed a significant impact on microbial communities and their associated metabolic patterns. Hydrogenotrophic methanogens, Methanobacterium sp. or Methanoculleus sp. were highly selected in the reactors, but the presence of co-dominant Methanosarcinales related species were required to produce higher amounts of CH4 than VFA.

中文翻译：

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生物甲烷化过程：关于高 H2 分压对微生物群落影响的新见解。

生物甲烷化是提高沼气中 CH4 含量的一种很有前景的解决方案。该过程包括将 H2 注入厌氧消化器，利用本地氢营养产甲烷菌的能力将注入的 H2 和厌氧消化过程产生的 CO2 转化为 CH4。然而，H2 的注入可能会通过影响厌氧消化器的微生物群落而导致过程干扰。因此，需要更好地了解本土微生物群落如何适应高 H2 分压。从处理不同类型废物的工业生物过程中产生的七种微生物接种剂在半连续反应器中暴露于高 H2 分压。运行 12 天后，即使 CH4 和挥发性脂肪酸 (VFA) 都作为最终产品生产，其中之一是主要产品。醋酸盐是最丰富的 VFA，占 VFA 总产量的 94%。根据接种物的来源，VFA 积累与 CH4 产生强烈反相关。区分了三组接种物：(1) 导致产生 CH4 的接种物，(2) 导致低比例产生甲烷和 VFA 的接种物，以及 (3) 导致主要 VFA 积累的接种物，主要是乙酸盐。有趣的是，VFA 的积累与接种物中古生菌的低比例高度相关，同型产乙酸菌的数量高于氢营养产甲烷菌，以及 Methanosarcinales 目成员的缺乏或非常低的丰度。当氢营养产甲烷菌和 Methanosarcina sp。共同主导整个行动。这项工作提供了关于微生物群落对高 H2 分压的反应的新见解。半连续反应器中的 H2 注入显示出对微生物群落及其相关代谢模式的显着影响。氢营养产甲烷菌，甲烷杆菌属。或 Methanoculleus sp。在反应器中被高度选择，但与 VFA 相比，需要存在共同主导的 Methanosarcinales 相关物种才能产生更高量的 CH4。