School of Biological Sciences, University of Oklahoma, Norman, OK, USA.
Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
NPJ Biofilms Microbiomes. 2024 Jul 3;10(1):55. doi: 10.1038/s41522-024-00525-5.
Climate changes significantly impact greenhouse gas emissions from wetland soil. Specifically, wetland soil may be exposed to oxygen (O) during droughts, or to sulfate (SO) as a result of sea level rise. How these stressors - separately and together - impact microbial food webs driving carbon cycling in the wetlands is still not understood. To investigate this, we integrated geochemical analysis, proteogenomics, and stoichiometric modeling to characterize the impact of elevated SO and O levels on microbial methane (CH) and carbon dioxide (CO) emissions. The results uncovered the adaptive responses of this community to changes in SO and O availability and identified altered microbial guilds and metabolic processes driving CH and CO emissions. Elevated SO reduced CH emissions, with hydrogenotrophic methanogenesis more suppressed than acetoclastic. Elevated O shifted the greenhouse gas emissions from CH to CO. The metabolic effects of combined SO and O exposures on CH and CO emissions were similar to those of O exposure alone. The reduction in CH emission by increased SO and O was much greater than the concomitant increase in CO emission. Thus, greater SO and O exposure in wetlands is expected to reduce the aggregate warming effect of CH and CO. Metaproteomics and stoichiometric modeling revealed a unique subnetwork involving carbon metabolism that converts lactate and SO to produce acetate, HS, and CO when SO is elevated under oxic conditions. This study provides greater quantitative resolution of key metabolic processes necessary for the prediction of CH and CO emissions from wetlands under future climate scenarios.
气候变化显著影响湿地土壤的温室气体排放。具体而言，湿地土壤在干旱期间可能会暴露于氧气 (O) 中，或者由于海平面上升而接触到硫酸盐 (SO)。这些胁迫因素（单独或共同作用）如何影响驱动湿地碳循环的微生物食物网，目前仍不清楚。为了研究这一点，我们综合了地球化学分析、蛋白质基因组学和化学计量建模，以表征 SO 和 O 水平升高对微生物甲烷 (CH) 和二氧化碳 (CO) 排放的影响。研究结果揭示了该群落对 SO 和 O 可用性变化的适应性反应，并确定了改变的微生物类群和代谢过程，这些过程驱动着 CH 和 CO 的排放。SO 的升高降低了 CH 的排放，氢营养型产甲烷作用比乙酸营养型产甲烷作用受到更大的抑制。O 的升高将温室气体排放从 CH 转移到 CO。SO 和 O 联合暴露对 CH 和 CO 排放的代谢影响与 O 单独暴露的影响相似。由于 SO 和 O 增加而导致的 CH 排放减少量远大于 CO 排放的相应增加量。因此，湿地中 SO 和 O 的暴露增加预计会降低 CH 和 CO 的总增温效应。代谢组学和化学计量建模揭示了一个独特的涉及碳代谢的子网络，当 SO 在有氧条件下升高时，该子网络可以将乳酸盐和 SO 转化为乙酸盐、HS 和 CO。这项研究为预测未来气候情景下湿地中 CH 和 CO 排放提供了更定量的关键代谢过程分辨率。
