Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, School of Sustainable Engineering and the Built Environment, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), 1001 S McAllister Ave, Tempe, AZ, USA.
Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA.
Chemosphere. 2022 Sep;303(Pt 1):134877. doi: 10.1016/j.chemosphere.2022.134877. Epub 2022 May 13.
Hydrogen (H) is a crucial electron donor for many processes in the environment including nitrate-, sulfate- and, iron-reduction, homoacetogenesis, and methanogenesis, and is a major determinant of microbial competition and metabolic pathways in groundwater, sediments, and soils. Despite the importance of H for many microbial processes in the environment, the total H consuming capacity (or H demand) of soils is generally unknown. Using soil microcosms with added H, the aims of this study were 1) to measure the H demand of geochemically diverse soils and 2) to define the processes leading to this demand. Study results documented a large range of H demand in soil (0.034-1.2 millielectron equivalents H g soil). The measured H demand greatly exceeded the theoretical demand predicted based on measured concentrations of common electron acceptors initially present in a library of 15 soils. While methanogenesis accounted for the largest fraction of H demand, humic acid reduction and acetogenesis were also significant contributing H-consuming processes. Much of the H demand could be attributed to CO produced during incubation from fermentation and/or acetoclastic methanogenesis. The soil initial total organic carbon showed the strongest correlation to H demand. Besides external additions, H was likely generated or cycled in the microcosms. Apart from fermentative H production, carboxylate elongation to produce C4-C7 fatty acids may have accounted for additional H production in these soils. Many of these processes, especially the organic carbon contribution is underestimated in microbial models for H consumption in natural soil ecosystems or during bioremediation of contaminants in soils.
氢（H）是环境中许多过程的重要电子供体，包括硝酸盐、硫酸盐和铁还原、同型乙酰生成和产甲烷作用，并且是地下水、沉积物和土壤中微生物竞争和代谢途径的主要决定因素。尽管 H 对于环境中的许多微生物过程都很重要，但土壤中总的 H 消耗能力（或 H 需求）通常是未知的。本研究使用添加 H 的土壤微宇宙，旨在 1）测量地球化学多样的土壤的 H 需求，2）定义导致这种需求的过程。研究结果记录了土壤中 H 需求的很大范围（0.034-1.2 毫电子当量 H g 土壤）。测量的 H 需求大大超过了根据最初存在于 15 种土壤文库中的常见电子受体的测量浓度预测的理论需求。虽然产甲烷作用占 H 需求的最大部分，但腐殖质还原和同型乙酰生成也是重要的 H 消耗过程。大部分 H 需求可归因于发酵和/或乙酸营养型产甲烷作用过程中在孵育期间产生的 CO。土壤初始总有机碳与 H 需求呈最强相关性。除了外部添加，H 可能在微宇宙中生成或循环。除了发酵产生的 H 之外，羧酸延伸产生 C4-C7 脂肪酸可能是这些土壤中额外 H 产生的原因。在自然土壤生态系统中或在土壤中污染物的生物修复过程中，微生物模型对 H 消耗的许多这些过程（特别是有机碳的贡献）估计不足。
