Methanogens are methane-producing, hydrogen-oxidizing (i.e., hydrogenotrophic) archaea. Numerous studies have associated methanogens with obesity, but these results have been inconsistent. One link to metabolism may be methanogens' hydrogen-oxidizing ability, thus reducing hydrogen partial pressure and thermodynamically enhancing fermentation of sugars to short-chain fatty acids that the host can absorb. Because research linking methanogenesis to human metabolism is limited, our goal with this exploratory analysis was to investigate relationships between methanogens and other hydrogenotrophs, along with the association of methanogens with human metabolizable energy. Using results from a randomized crossover feeding study including a western diet and a high-fiber diet, well-characterized human participants, and continuous methane measurements, we analyzed hydrogenotroph abundance and activity, fecal and serum short-chain fatty acids, and host metabolizable energy between high and low methane producers. We detected methanogens in about one-half of participants. We found no evidence that methanogens' consumption of hydrogen to produce methane affected other hydrogenotrophs. High methane producers had greater serum propionate and greater gene and transcript abundance of a key enzyme of the hydrogen-consuming, propionate-producing succinate pathway. High methane producers also had greater metabolizable energy than low producers on the high-fiber diet. A network analysis revealed positive relationships between the methane-production rate and bacteria capable of degrading fiber and fermenting fiber-degradation products, thus forming a trophic chain to extract additional energy from undigested substrates. Our results show that methanogenesis in a microbial consortium was linked to host metabolizable energy through enhanced microbial production, and subsequent host absorption, of short-chain fatty acids.

Keywords: human metabolism; hydrogenotrophs; metabolizable energy; methane; methanogens; short-chain fatty acids.

© The Author(s) 2025. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.

产甲烷菌是一种能够产生甲烷并氧化氢的古细菌（即，氢营养型）。许多研究将产甲烷菌与肥胖联系在一起，但这些结果并不一致。一个可能的代谢关联是，由于产甲烷菌具有氧化氢的能力，这会降低氢的部分压力，并从热力学上增强糖发酵为短链脂肪酸的过程，而这些短链脂肪酸可被宿主吸收。鉴于将产甲烷作用与人类代谢联系起来的研究有限，我们在此探索性分析中的目标是研究产甲烷菌及其他氢营养型微生物之间的关系，以及它们与人体可代谢能量的关联。利用随机交叉饮食研究结果（包括西式饮食和高纤维饮食）、特征明确的人类参与者及连续测量的甲烷数据，我们分析了氢营养型微生物丰度与活性、粪便及血清中的短链脂肪酸含量，以及在高产甲烷者和低产甲烷者之间宿主可代谢能量的变化。我们在大约一半的研究对象中检测到了产甲烷菌。我们没有发现证据表明，由于产生甲烷而消耗氢气会影响其他氢营养型微生物。高产甲烷者具有较高的血清丙酸盐浓度及与氢利用、丙酸生成的琥珀酸途径中的关键酶基因和转录本丰度较高。在高纤维饮食条件下，高产甲烷者还比低产甲烷者表现出更高的可代谢能量。网络分析揭示了甲烷生产速率与其他能够降解纤维并发酵纤维降解产物的细菌之间的正相关关系，形成了一个营养链以从未消化底物中提取更多能量。我们的结果表明，在微生物群落中的产甲烷作用与宿主可代谢能量之间存在联系，并且是通过增强微生物产生短链脂肪酸（随后由宿主吸收）来实现。

关键词：人类代谢；氢营养型细菌；可代谢能量；甲烷；产甲烷菌；短链脂肪酸。

© The Author(s) 2025. Oxford University Press 出版，代表国际微生物生态学会出版。