Peterse Ida F, Pol Arjan, Cremers Geert, Berben Tom, van Alen Theo A, Op den Camp Huub J M, Veraart Annelies J, Lücker Sebastian
Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Faculty of Science, Radboud University, Nijmegen, the Netherlands.
Department of Ecology, Radboud Institute for Biological and Environmental Sciences, Faculty of Science, Radboud University, Nijmegen, the Netherlands.
Environ Microbiol. 2025 Aug;27(8):e70163. doi: 10.1111/1462-2920.70163.
Hydrogen (H) and methane (CH) are produced in the anoxic layers of wetlands and sediments. In the overlaying oxygenated surface layers, these gases become available for oxidation by aerobic hydrogenotrophic and methanotrophic microorganisms. While H oxidation by verrucomicrobial methane-oxidising bacteria (MOB) is extensively studied, less is known about this metabolism in MOB from the class Alphaproteobacteria, which frequently inhabit wetlands. We show that Methylocystis bryophila H2s, Methylocapsa aurea KYG, and "Methylosinus acidophilus" 29 encode diverse hydrogenases, instantly oxidise H when cultivated under CH-limited and low-oxygen conditions, under which hydrogenase transcription is upregulated compared to CH-replete conditions. H exposure accelerated the maximum H oxidation rates but caused no upregulation of hydrogenases. Furthermore, while CH oxidation activity was affected by substrate-limited growth conditions, H oxidation rates remained unaffected, and H supply to CH-limited chemostats caused increased biomass yield. Moreover, CH oxidation was severely inhibited by sulfide (HS), while H and methanol oxidation rates were only moderately affected. In summary, the ability to conserve energy from H oxidation increases resilience and enhances growth of alphaproteobacterial methanotrophs in CH-limited environments, which revises the ecological role of these MOB in ecosystems with naturally fluctuating CH and H concentrations.
氢气（H）和甲烷（CH）在湿地和沉积物的缺氧层中产生。在覆盖的含氧表层中，这些气体可供好氧氢营养型和甲烷营养型微生物氧化。虽然疣微菌纲甲烷氧化细菌（MOB）对氢气的氧化已得到广泛研究，但对于经常栖息在湿地中的α-变形菌纲MOB的这种代谢了解较少。我们发现，嗜藓甲基孢囊菌H2s、金色甲基帽菌KYG和“嗜酸甲基弯曲菌”29编码多种氢化酶，在甲烷受限和低氧条件下培养时能立即氧化氢气，与甲烷充足条件相比，此时氢化酶转录上调。暴露于氢气会加快最大氢气氧化速率，但不会导致氢化酶上调。此外，虽然甲烷氧化活性受底物限制生长条件的影响，但氢气氧化速率不受影响，向甲烷受限的恒化器供应氢气会提高生物量产量。此外，甲烷氧化受到硫化物（HS）的严重抑制，而氢气和甲醇氧化速率仅受到中度影响。总之，从氢气氧化中保存能量的能力增强了α-变形菌纲甲烷营养菌在甲烷受限环境中的恢复力并促进其生长，这修正了这些MOB在甲烷和氢气浓度自然波动的生态系统中的生态作用。
