Braga Nan Lucia, Trably Eric, Santa-Catalina Gaëlle, Bernet Nicolas, Delgenès Jean-Philippe, Escudié Renaud
INRAE, Univ Montpellier, LBE, 102 Avenue des Etangs, 11100 Narbonne, France.
Biotechnol Biofuels. 2020 Aug 10;13:141. doi: 10.1186/s13068-020-01776-y. eCollection 2020.
Biomethanation is a promising solution to upgrade the CH content in biogas. This process consists in the injection of H into an anaerobic digester, using the capacity of indigenous hydrogenotrophic methanogens for converting the injected H and the CO generated from the anaerobic digestion process into CH. However, the injection of H 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 H partial pressures is therefore required.
Seven microbial inocula issued from industrial bioprocesses treating different types of waste were exposed to a high H partial pressure in semi-continuous reactors. After 12 days of operation, even though both CH 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 CH production according to the source of inoculum. Three clusters of inocula were distinguished: (1) inocula leading to CH 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 order. The best methanogenic performances were obtained when hydrogenotrophic methanogens and sp. co-dominated all along the operation.
New insights on the microbial community response to high H partial pressure are provided in this work. H injection in semi-continuous reactors showed a significant impact on microbial communities and their associated metabolic patterns. Hydrogenotrophic methanogens, sp. or sp. were highly selected in the reactors, but the presence of co-dominant related species were required to produce higher amounts of CH than VFA.
生物甲烷化是提高沼气中CH含量的一种有前景的解决方案。该过程包括将H注入厌氧消化器，利用本地氢营养型产甲烷菌将注入的H和厌氧消化过程产生的CO转化为CH的能力。然而，注入H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，需要更好地了解本地微生物群落如何适应高H分压。
来自处理不同类型废物的工业生物过程的七种微生物接种物在半连续反应器中暴露于高H分压下。运行12天后，尽管CH和挥发性脂肪酸（VFA）都是最终产物，但其中一种是主要产物。乙酸盐是最丰富的VFA，占总VFA产量的94%。根据接种物来源，VFA积累与CH产量呈强烈负相关。区分出三类接种物：（1）导致CH产生的接种物，（2）导致产生低比例甲烷和VFA的接种物，（3）导致主要是VFA（主要是乙酸盐）积累的接种物。有趣的是，VFA积累与接种物中古菌比例低、同型产乙酸菌数量高于氢营养型产甲烷菌以及该目中成员不存在或丰度极低高度相关。当氢营养型产甲烷菌和 菌在整个运行过程中共同占主导地位时，获得了最佳产甲烷性能。
这项工作提供了关于微生物群落对高H分压反应的新见解。在半连续反应器中注入H对微生物群落及其相关代谢模式有显著影响。氢营养型产甲烷菌、 菌或 菌在反应器中被高度选择，但需要共同占主导地位的相关物种存在才能产生比VFA更多的CH。
