The aerobic methane-oxidizing bacteria (MOB) are suggested to be important for the removal of oxygen from subterranean aquifers that become oxygenated by natural and engineering processes. This is primarily because MOB are ubiquitous in the environment and in addition reduce oxygen efficiently. The biogeochemical factors that will control the success of the aerobic MOB in these kinds of underground aquifers remain unknown. In this study, viable and cultivable MOB occurring at natural and engineered deep granitic aquifers targeted for the disposal of spent nuclear fuel (SNF) in the Fennoscandian Shield (approximately 3-1000 m) were enumerated. The numbers were correlated with in situ salinity, methane concentrations, conductivity, pH, and depth. A mixed population habiting freshwater aquifers (approximately 3-20 m), a potential source for the inoculation of MOB into the deeper aquifers was tested for tolerance to NaCl, temperature, pH, and an ability to produce cysts and exospores. Extrapolations show that due to changing in situ parameters (salinity, conductivity, and pH), the numbers of MOB in the aquifers dropped quickly with depth. A positive correlation between the most probable numbers of MOB and methane concentrations was observed. Furthermore, the tolerance-based tests of cultured strains indicated that the MOB in the shallow aquifers thrived best in mesophilic and neutrophilic conditions as opposed to the hyperthermophilic and alkaliphilic conditions expected to develop in an engineered subterranean SNF repository. Overall, the survival of the MOB both quantitatively and physiologically in the granitic aquifers was under the strong influence of biogeochemical factors that are strongly depth-dependent.

中文翻译：

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通过培养分析推断，好氧甲烷氧化细菌在天然和工程地下火成岩含水层中定殖的限制。

有氧甲烷氧化细菌（MOB）被认为对于从地下含水层中去除氧气很重要，地下含水层由于自然和工程过程而被氧化。这主要是因为MOB在环境中无处不在，此外还可以有效地减少氧气。在这些地下含水层中，控制好氧MOB成功的生物地球化学因素仍然未知。在这项研究中，列举了在天然和工程化的深层花岗岩含水层中发生的可行和可培养的MOB，其目标是在Fennoscandian Shield（约3-1000 m）中处置乏核燃料（SNF）。这些数字与原位盐度，甲烷浓度，电导率，pH和深度相关。居住着淡水含水层（大约3-20 m）的混合人群，测试了将MOB接种到深层含水层中的潜在来源对NaCl的耐受性，温度，pH值以及产生囊肿和孢子囊的能力。外推表明，由于原位参数（盐度，电导率和pH）的变化，含水层中MOB的数量随深度而迅速下降。观察到最可能的MOB数量与甲烷浓度之间呈正相关。此外，对培养菌株的基于耐受性的测试表明，与预期在工程地下SNF储存库中发展的高嗜热和嗜碱条件相反，浅层含水层中的MOB在嗜温和嗜中性条件下表现最佳。总体，