Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Science, No. 9 Section 4, Renmin Nan Road, Chengdu, Sichuan, People's Republic of China.
Biomass Energy Engineering Research Centre, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, People's Republic of China.
World J Microbiol Biotechnol. 2020 May 22;36(6):79. doi: 10.1007/s11274-020-02856-9.
Anaerobic digestion is an effective process for the treatment of organic solid waste and wastewater and the production of biogas, which is a clean energy source. The carbon dioxide in the biogas can be converted into methane using hydrogen generated from water electrolysis through an approach referred to as power-to-gas. Recently, hydrogen has been added to digesters as an in-situ or ex-situ biogas upgrade to reduce the levels of carbon dioxide. Biogas production systems consist of microbial complexes with highly organized microorganisms in different niches, which can either produce or consume hydrogen. However, the produced endogenous hydrogen should be constantly consumed to maintain a low hydrogen partial pressure. This review addresses the biochemical processes of anaerobic digestion and hydrogen-related microorganisms, including fermentative acid-producing bacteria, syntrophic organic acid degrading bacteria, syntrophic acetate-oxidizing bacteria, homoacetogens, hydrogenotrophic methanogens, and newly reported hydrogen-dependent methylotrophic methanogens. This study also investigates (1) the role of endogenous hydrogen as an intermediate metabolite and of interspecies electron transfer in anaerobic digestion, (2) effects of exogenous hydrogen addition on microbial community structure and metabolic processes, and (3) recent developments regarding in-situ and ex-situ biogas upgrading systems via hydrogen addition.
厌氧消化是一种有效处理有机固体废物和废水以及生产沼气的方法，沼气是一种清洁能源。沼气中的二氧化碳可以通过水电解产生的氢气转化为甲烷，这种方法被称为“电转气”。最近，氢气已被添加到消化器中，作为原位或异位沼气升级的方法，以降低二氧化碳水平。沼气生产系统由微生物群落组成，不同小生境中的微生物高度组织化，可以产生或消耗氢气。然而，为了维持低氢气分压，产生的内源性氢气需要不断消耗。本综述介绍了厌氧消化过程中的生化过程和与氢气相关的微生物，包括发酵产酸细菌、协同有机物降解细菌、协同乙酸氧化细菌、同型产乙酸菌、氢营养型产甲烷菌和新报道的依赖氢气的甲基营养型产甲烷菌。本研究还探讨了（1）内源性氢气作为中间代谢物和种间电子传递在厌氧消化中的作用，（2）外加氢气对微生物群落结构和代谢过程的影响，以及（3）通过添加氢气实现原位和异位沼气升级系统的最新进展。
