Kolb Steffen, Horn Marcus A
Department of Ecological Microbiology, University of Bayreuth Bayreuth, Germany.
Front Microbiol. 2012 Mar 2;3:78. doi: 10.3389/fmicb.2012.00078. eCollection 2012.
Acidic wetlands are global sources of the atmospheric greenhouse gases methane (CH(4)), and nitrous oxide (N(2)O). Consumption of both atmospheric gases has been observed in various acidic wetlands, but information on the microbial mechanisms underlying these phenomena is scarce. A substantial amount of CH(4) is consumed in sub soil by aerobic methanotrophs at anoxic-oxic interfaces (e.g., tissues of Sphagnum mosses, rhizosphere of vascular plant roots). Methylocystis-related species are likely candidates that are involved in the consumption of atmospheric CH(4) in acidic wetlands. Oxygen availability regulates the activity of methanotrophs of acidic wetlands. Other parameters impacting on the methanotroph-mediated CH(4) consumption have not been systematically evaluated. N(2)O is produced and consumed by microbial denitrification, thus rendering acidic wetlands as temporary sources or sinks for N(2)O. Denitrifier communities in such ecosystems are diverse, and largely uncultured and/or new, and environmental factors that control their consumption activity are unresolved. Analyses of the composition of N(2)O reductase genes in acidic wetlands suggest that acid-tolerant Proteobacteria have the potential to mediate N(2)O consumption in such soils. Thus, the fragmented current state of knowledge raises open questions concerning methanotrophs and denitrifiers that consume atmospheric CH(4) and N(2)O in acidic wetlands.
酸性湿地是大气温室气体甲烷（CH₄）和一氧化二氮（N₂O）的全球排放源。在各种酸性湿地中均观察到这两种大气气体的消耗情况，但关于这些现象背后的微生物机制的信息却很少。在缺氧-有氧界面（如泥炭藓组织、维管植物根际），好氧甲烷氧化菌在亚表层土壤中消耗大量的CH₄。与甲基孢囊菌相关的物种可能是参与酸性湿地中大气CH₄消耗的候选者。氧气的可利用性调节着酸性湿地中甲烷氧化菌的活性。其他影响甲烷氧化菌介导的CH₄消耗的参数尚未得到系统评估。N₂O通过微生物反硝化作用产生和消耗，因此酸性湿地是N₂O的临时排放源或汇。此类生态系统中的反硝化菌群落多样，且大多未培养和/或为新物种，控制其消耗活动的环境因素尚未明确。对酸性湿地中N₂O还原酶基因组成的分析表明，耐酸变形菌有可能介导此类土壤中N₂O的消耗。因此，目前知识的碎片化状态引发了关于在酸性湿地中消耗大气CH₄和N₂O的甲烷氧化菌和反硝化菌的开放性问题。
