Methane, a non-expensive natural substrate, is used by Methylocystis spp. as a sole source of carbon and energy. Here, we assessed whether Methylocystis sp. strain SC2 is able to also utilize hydrogen as an energy source. The addition of 2% H₂ to the culture headspace had the most significant positive effect on the growth yield under CH₄ (6%) and O₂ (3%) limited conditions. The SC2 biomass yield doubled from 6.41 (±0.52) to 13.82 (±0.69) mg cell dry weight per mmol CH₄, while CH₄ consumption was significantly reduced. Regardless of H₂ addition, CH₄ utilization was increasingly redirected from respiration to fermentation-based pathways with decreasing O₂/CH₄ mixing ratios. Theoretical thermodynamic calculations confirmed that hydrogen utilization under oxygen-limited conditions doubles the maximum biomass yield compared to fully aerobic conditions without H₂ addition. Hydrogen utilization was linked to significant changes in the SC2 proteome. In addition to hydrogenase accessory proteins, the production of Group 1d and Group 2b hydrogenases was significantly increased in both short- and long-term incubations. Both long-term incubation with H₂ (37 d) and treatments with chemical inhibitors revealed that SC2 growth under hydrogen-utilizing conditions does not require the activity of complex I. Apparently, strain SC2 has the metabolic capacity to channel hydrogen-derived electrons into the quinone pool, which provides a link between hydrogen oxidation and energy production. In summary, H₂ may be a promising alternative energy source in biotechnologically oriented methanotroph projects that aim to maximize biomass yield from CH_4, such as the production of high-quality feed protein.

甲烷是一种非昂贵的天然底物，被Methylocystis spp 使用。作为碳和能源的唯一来源。在这里，我们评估了Methylocystis sp。SC2菌株也能够利用氢作为能源。在 CH ₄ (6%) 和 O ₂ (3%) 限制条件下，向培养顶空添加 2% H ₂对生长产量具有最显着的积极影响。SC2 生物质产量从 6.41 (±0.52) 到 13.82 (±0.69) mg 细胞干重/mmol CH ₄翻倍，同时 CH ₄消耗显着减少。无论 H ₂添加，CH ₄随着 O ₂ /CH ₄混合比的降低，利用越来越多地从呼吸转向基于发酵的途径。理论热力学计算证实，与不添加 H _{2 的}完全有氧条件相比，在限氧条件下利用氢可使最大生物质产量增加一倍。氢利用与 SC2 蛋白质组的显着变化有关。除了氢化酶辅助蛋白外，第 1d 组和第 2b 组氢化酶的产量在短期和长期孵育中均显着增加。与 H ₂长期孵育(37 d) 和化学抑制剂处理表明 SC2 在氢利用条件下的生长不需要复合物 I 的活性。在氢气氧化和能源生产之间。总之，在以生物技术为导向的甲烷氧化菌项目中，H ₂可能是一种很有前途的替代能源，这些项目旨在最大限度地提高 CH _{4 的}生物质产量_，例如生产高质量的饲料蛋白质。