Extraction of natural gas from unconventional hydrocarbon reservoirs by hydraulic fracturing raises concerns about methane migration into groundwater. Microbial methane oxidation can be a significant methane sink. Here, we inoculated replicated, sand-packed, continuous mesocosms with groundwater from a field methane release experiment. The mesocosms experienced thirty-five weeks of dynamic methane, oxygen and nitrate concentrations. We determined concentrations and stable isotope signatures of methane, carbon dioxide and nitrate and monitored microbial community composition of suspended and attached biomass. Methane oxidation was strictly dependent on oxygen availability and led to enrichment of 13 C in residual methane. Nitrate did not enhance methane oxidation under oxygen limitation. Methylotrophs persisted for weeks in the absence of methane, making them a powerful marker for active as well as past methane leaks. Thirty-nine distinct populations of methylotrophic bacteria were observed. Methylotrophs mainly occurred attached to sediment particles. Abundances of methanotrophs and other methylotrophs were roughly similar across all samples, pointing at transfer of metabolites from the former to the latter. Two populations of Gracilibacteria (Candidate Phyla Radiation) displayed successive blooms, potentially triggered by a period of methane famine. This study will guide interpretation of future field studies and provides increased understanding of methylotroph ecophysiology.

中文翻译：

---

地下水中膜的甲烷氧化和甲基营养型种群动态。

通过水力压裂从非常规油气藏中提取天然气引起了人们对甲烷向地下水中迁移的关注。微生物甲烷氧化可能是重要的甲烷汇。在这里，我们用田间甲烷释放实验中的地下水接种了重复的，沙堆的，连续的中膜。中观经历了35周的动态甲烷，氧气和硝酸盐浓度。我们确定了甲烷，二氧化碳和硝酸盐的浓度和稳定的同位素特征，并监测了悬浮和附着的生物量的微生物群落组成。甲烷氧化严格取决于氧气的可用性，并导致残留甲烷中的13 C富集。在氧限制下，硝酸盐没有增强甲烷的氧化作用。在没有甲烷的情况下，甲基营养菌会持续数周，使它们成为主动泄漏和过去甲烷泄漏的有力标记。观察到39个不同的甲基营养细菌种群。甲基营养菌主要发生在沉积物颗粒上。在所有样品中，甲烷营养菌和其他甲基营养菌的丰度大致相似，这表明代谢物从前者转移到后者。两个种群的灰霉菌（候选Phyla辐射）显示出连续的水华，可能是由一段时间的甲烷饥荒引发的。这项研究将指导对未来野外研究的解释，并提供对甲基营养生物生态生理学的更多理解。在所有样品中，甲烷营养菌和其他甲基营养菌的丰度大致相似，这表明代谢物从前者转移到后者。两个种群的灰霉菌（候选Phyla辐射）显示出连续的水华，可能是由一段时间的甲烷饥荒引发的。这项研究将指导对未来野外研究的解释，并提供对甲基营养生物生态生理学的更多理解。在所有样品中，甲烷营养菌和其他甲基营养菌的丰度大致相似，这表明代谢物从前者转移到后者。两个种群的灰霉菌（候选Phyla辐射）显示出连续的水华，可能是由一段时间的甲烷饥荒引发的。这项研究将指导对未来野外研究的解释，并提供对甲基营养生物生态生理学的更多理解。