Department for Sustainable Food Process, DiSTAS, Catholic University of the Sacred Heart, 29122, Piacenza, Italy.
Department of Environmental Engineering, Technical University of Denmark, 2800, Kongens Lyngby, Denmark.
Microbiome. 2018 Oct 27;6(1):194. doi: 10.1186/s40168-018-0583-4.
The expansion of renewable energy produced by windmills and photovoltaic panels has generated a considerable electricity surplus, which can be utilized in water electrolysis systems for hydrogen production. The resulting hydrogen can then be funneled to anaerobic digesters for biogas upgrading (biomethanation) purposes (power-to-methane) or to produce high value-added compounds such as short-chain fatty acids (power-to-chemicals). Genome-centric metagenomics and metatranscriptomic analyses were performed to better understand the metabolic dynamics associated with H injection in two different configurations of anaerobic digesters treating acidic wastes, specifically cheese manufacturing byproducts. These approaches revealed the key-genes involved in methanation and carbon fixation pathways at species level.
The biogas upgrading process in the single-stage configuration increased the CH content by 7%. The dominant methanogenic species responsible for the upregulation of the hydrogenotrophic pathway in this reactor was Methanothermobacter wolfeii UC0008. In the two-stage configuration, H injection induced an upregulation of CO fixation pathways producing short-chain fatty acids, mainly acetate and butyrate. In this configuration, the abundant species Anaerobaculum hydrogeniformans UC0046 and Defluviitoga tunisiensis UC0050 primarily upregulated genes related to electron transport chains, suggesting putative syntrophisms with hydrogen scavenger microbes. Interestingly, Tepidanaerobacter acetatoxydans UC0018 did not act as an acetate-oxidizer in either reactor configurations, and instead regulated pathways involved in acetate production and uptake. A putative syntrophic association between Coprothermobacter proteolyticus UC0011 and M. wolfeii UC0008 was proposed in the two-stage reactor. In order to support the transcriptomic findings regarding the hydrogen utilization routes, an advanced bioconversion model was adapted for the simulation of the single- and two-stage reactor setups.
This is the first study investigating biogas reactor metatranscriptome dynamics following hydrogen injection for biomethanation and carbon fixation to short-chain fatty acids purposes. The same microbes showed different patterns of metabolic regulation in the two reactor configurations. It was observed an effect of the specialized acidogenic reactor on the overall microbial consortium composition and activity in the two-stage digester. There were also suggested the main species responsible for methanation, short-chain fatty acids production, and electron transport chain mechanisms, in both reactor configurations.
风力涡轮机和光伏电池板产生的可再生能源的扩张产生了相当多的电力过剩，可以利用水电解系统生产氢气。产生的氢气可以输送到厌氧消化器进行沼气升级（生物甲烷化）（电力到甲烷）或生产高附加值化合物，如短链脂肪酸（电力到化学品）。进行了基于基因组的宏基因组学和宏转录组学分析，以更好地了解在处理酸性废物的两种不同厌氧消化器配置中注入 H 时相关的代谢动态，特别是奶酪制造副产物。这些方法揭示了物种水平上参与甲烷化和碳固定途径的关键基因。
单级配置中的沼气升级过程使 CH 含量增加了 7%。在该反应器中负责上调氢营养途径的主要产甲烷物种是 Methanothermobacter wolfeii UC0008。在两级配置中，H 注入诱导了 CO 固定途径的上调，产生了短链脂肪酸，主要是乙酸和丁酸。在这种配置中，丰富的物种 Anaerobaculum hydrogeniformans UC0046 和 Defluviitoga tunisiensis UC0050 主要上调了与电子传递链相关的基因，表明与氢清除微生物存在潜在的共生关系。有趣的是，Tepidanaerobacter acetatoxydans UC0018 在两种反应器配置中都不作为乙酸氧化菌，而是调节参与乙酸产生和摄取的途径。在两级反应器中，提出了 Coprothermobacter proteolyticus UC0011 和 M. wolfeii UC0008 之间的潜在共生关系。为了支持关于氢利用途径的转录组研究结果，采用了一种先进的生物转化模型来模拟单级和两级反应器设置。
这是第一项研究，调查了用于生物甲烷化和碳固定生产短链脂肪酸的氢气注入后沼气反应器的宏转录组动力学。相同的微生物在两种反应器配置中表现出不同的代谢调节模式。观察到专门的产酸反应器对两级消化器中整体微生物群落组成和活性的影响。还提出了两种反应器配置中负责甲烷化、短链脂肪酸生产和电子传递链机制的主要物种。
