Xue Jie, Deutzmann Jörg Stefan, Matis Nicole, Kracke Frauke, Spormann Alfred, Gu Wenyu
Environmental Engineering Institute IIE-ENAC, Laboratory MICROBE, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Department of Civil and Environmental Engineering, Stanford University, Stanford, California, USA.
Microbiol Spectr. 2025 Aug 6:e0035925. doi: 10.1128/spectrum.00359-25.
Hydrogenotrophic methanogens play a key role in anaerobic ecosystems by catalyzing the bioconversion of hydrogen (H) and carbon dioxide (CO) into methane (CH) and water. This metabolic process is the basis of biological power-to-methane (PtM) technology, a promising solution for the long-term storage of surplus renewable energy as CH. Its successful application can be improved through a deeper understanding of methanogen physiology, particularly the metabolic response to intermittent substrate supply of H or CO. In batch cultures of PtM-relevant strains, mesophilic and thermophilic , we determined the apparent for dissolved inorganic carbon (DIC) to be 0.60 and 1.65 mmol L, respectively, which correspond to near-maximum CH production rates when CO partial pressures exceed 350 Pa at 30°C or 1.95 kPa at 60°C, at pH 7. Focusing on , cultivation in chemostats under either H or CO limitation did not affect the yield or activity of methanogenesis. However, differences emerged when was completely starved of either CO or H. demonstrated a higher tolerance to H starvation compared to CO starvation, resulting in shorter lag times and increased methanogenesis activity upon revival with replenished substrates. CO-starved cells displayed higher intracellular FH/F and NADH/NAD ratios and were more susceptible to O inactivation, indicating that the accumulation of reducing equivalents may be linked to cell damage. These insights can help stabilize the operation of PtM processes by adjusting the ratio of H to CO feed during intermittent operations or shutdowns.IMPORTANCEMicrobial physiology has increasingly been studied under dynamic substrate conditions, expanding beyond the classical focus on balanced growth. While starvation is typically associated with a halt in cellular growth and activity, how cells enter starvation influences their recovery dynamics. We demonstrate that starvation caused by a lack of electron donor vs electron acceptor results in distinctly different revival behaviors in the methanogenic Archaea, . Methanogens play a crucial role in the global carbon cycle, participating in the anaerobic breakdown of organic matter to methane and carbon dioxide. They are also of biotechnological significance, being central to anaerobic digestion processes and power-to-gas technology. Thus, our results showing improved recovery from electron donor over electron acceptor starvation may prove essential for optimizing methanogenesis processes across various applications.
氢营养型产甲烷菌在厌氧生态系统中发挥着关键作用，它能催化氢气（H₂）和二氧化碳（CO₂）生物转化为甲烷（CH₄）和水。这一代谢过程是生物电制甲烷（PtM）技术的基础，该技术是将多余可再生能源以CH₄形式长期储存的一种有前景的解决方案。通过更深入地了解产甲烷菌生理学，特别是其对H₂或CO₂间歇性底物供应的代谢反应，可以改进其成功应用。在与PtM相关菌株的分批培养中，嗜温菌和嗜热菌，我们测定了溶解无机碳（DIC）的表观Kₘ分别为0.60和1.65 mmol/L，这对应于当CO₂分压在30°C时超过350 Pa或在60°C时超过1.95 kPa、pH为7时接近最大CH₄产生速率。聚焦于，在恒化器中于H₂或CO₂限制条件下培养不会影响产甲烷的产量或活性。然而，当完全缺乏CO₂或H₂时会出现差异。与CO₂饥饿相比，表现出对H₂饥饿更高的耐受性，导致延迟时间更短，并且在用补充底物复苏后产甲烷活性增加。CO₂饥饿的细胞显示出更高的细胞内FH₂/F₄和NADH/NAD⁺比值，并且对O₂失活更敏感，这表明还原当量的积累可能与细胞损伤有关。这些见解有助于通过在间歇操作或停机期间调整H₂与CO₂进料的比例来稳定PtM过程的运行。重要性在动态底物条件下对微生物生理学的研究日益增多，超越了传统上对平衡生长的关注。虽然饥饿通常与细胞生长和活性的停止相关，但细胞如何进入饥饿状态会影响其恢复动态。我们证明，由缺乏电子供体与电子受体导致的饥饿在产甲烷古菌中产生明显不同的复苏行为。产甲烷菌在全球碳循环中起着关键作用，参与有机物厌氧分解为甲烷和二氧化碳。它们在生物技术方面也具有重要意义，是厌氧消化过程和电转气技术的核心。因此，我们的结果表明从电子供体饥饿中恢复比从电子受体饥饿中恢复更好，这对于优化各种应用中的产甲烷过程可能至关重要。
