Aerobic bacterial methane synthesis
Aerobic bacterial methane synthesis
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DOI：
10.1073/pnas.2019229118
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
Qian Wang;Abdullah Alowaifeer;Patricia Kerner;Narayanaganesh Balasubramanian;Angela Patterson;W. Christian;Angela Tarver;J. Dore;R. Hatzenpichler;B. Bothner;T. McDermott
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作者：
Qian Wang;Abdullah Alowaifeer;Patricia Kerner;Narayanaganesh Balasubramanian;Angela Patterson;W. Christian;Angela Tarver;J. Dore;R. Hatzenpichler;B. Bothner;T. McDermott
本文总结的观察结果有助于微生物生态学正在进行的范式转变，记录了生态系统功能的一个新特性，进一步挑战了生物甲烷（CH 4）生产严格是一个厌氧过程的看法。相关的代谢产物，一个模型的细菌分离株，基因和酶的鉴定，我们展示了如何可以想象的是，这种属性可以广泛分布在生物圈中，并有助于全球甲烷排放量。科学上，这项研究将使调查线，将扩大我们的理解CH 4的合成和排放的性质，并说明如何CH 4合成实际上可能作为一个连接的C和N循环的性质。与一系列生物体相关的生物甲烷（CH 4）合成的报告在文献中稳步积累。这并非没有争议，在大多数情况下，这一过程在基因和酶水平上知之甚少。在海洋和淡水环境中，甲烷过饱和的好氧表面沃茨已被称为“甲烷悖论”，因为生物甲烷合成被认为是一个严格的厌氧过程进行的O2-敏感的产甲烷菌。在过去十年中，人们对这一现象的兴趣激增，因为了解这种强效温室气体的源和汇非常重要。在黄石国家公园黄石湖的工作中，我们展示了微生物转化甲胺为甲烷，并分离和表征了一种具有这种活性的噬酸菌属。此外，我们确定并克隆了一个基因的关键这个过程（编码磷酸吡啶羟胺依赖性天冬氨酸转氨酶），并证明这种属性可以转移到大肠杆菌与此基因，并会发生作为一个纯化的酶。这个以前未被认识的过程揭示了环境循环的甲烷，这表明O2不敏感，生态相关的好氧甲烷合成可能是广泛分布在环境中，应该考虑在甲烷建模工作。
Significance Observations summarized herein contribute to an ongoing paradigm shift in microbial ecology, documenting an emergent property of ecosystem function that further challenges the perception that biogenic methane (CH4) production is strictly an anaerobic process. Relevant metabolites, a model bacterial isolate, gene, and enzyme are identified, and we show how this property can conceivably be broadly distributed in the biosphere and contribute to global CH4 emissions. Scientifically, this study will enable lines of investigation that will expand our understanding of CH4 synthesis and emission in nature and illustrates how CH4 synthesis may actually serve as a nexus for the C and N cycles in nature. Reports of biogenic methane (CH4) synthesis associated with a range of organisms have steadily accumulated in the literature. This has not happened without controversy and in most cases the process is poorly understood at the gene and enzyme levels. In marine and freshwater environments, CH4 supersaturation of oxic surface waters has been termed the “methane paradox” because biological CH4 synthesis is viewed to be a strictly anaerobic process carried out by O2-sensitive methanogens. Interest in this phenomenon has surged within the past decade because of the importance of understanding sources and sinks of this potent greenhouse gas. In our work on Yellowstone Lake in Yellowstone National Park, we demonstrate microbiological conversion of methylamine to CH4 and isolate and characterize an Acidovorax sp. capable of this activity. Furthermore, we identify and clone a gene critical to this process (encodes pyridoxylamine phosphate-dependent aspartate aminotransferase) and demonstrate that this property can be transferred to Escherichia coli with this gene and will occur as a purified enzyme. This previously unrecognized process sheds light on environmental cycling of CH4, suggesting that O2-insensitive, ecologically relevant aerobic CH4 synthesis is likely of widespread distribution in the environment and should be considered in CH4 modeling efforts.