Department of Microbiology and Plant Biology and the Institute for Energy and the Environment, University of Oklahoma, Norman, OK 73019-0390, USA.
Howard Live Oak, LLC, Statistics, Norman, OK 72019, USA.
FEMS Microbiol Ecol. 2017 Apr 1;93(4). doi: 10.1093/femsec/fix040.
The potential for modern coalfield methanogenesis was assessed using formation water from the Illinois Basin, Powder River Basin and Cook Inlet gas field as inocula for nutrient-replete incubations amended with C1-C5 fatty acids as presumed intermediates formed during anaerobic coal biodegradation. Instead of the expected rapid mineralization of these substrates, methanogenesis was inordinately slow (∼1 μmol day-1), following long lag periods (>100 days), and methane yields typically did not reach stoichiometrically expected levels. However, a gene microarray confirmed the potential for a wide variety of microbiological functions, including methanogenesis, at all sites. The Cook Inlet incubations produced methane at a relatively rapid rate when amended with butyrate (r = 0.98; p = 0.001) or valerate (r = 0.84; p = 0.04), a result that significantly correlated with the number of positive mcr gene sequence probes from the functional gene microarray and was consistent with the in situ detection of C4-C5 alkanoic acids. This finding highlighted the role of syntrophy for the biodegradation of the softer lignite and subbituminous coal in this formation, but methanogenesis from the harder subbituminous and bituminous coals in the other fields was less apparent. We conclude that coal methanogenesis is probably not limited by the inherent lack of metabolic potential, the presence of alternate electron acceptors or the lack of available nutrients, but more likely restricted by the inherent recalcitrance of the coal itself.
采用伊利诺伊盆地、粉河盆地和库克湾气田的地层水作为接种物，对现代煤田甲烷生成的潜力进行了评估，这些地层水富含营养物质，添加了 C1-C5 脂肪酸作为假定的中间产物，这些中间产物是在厌氧煤生物降解过程中形成的。这些底物没有预期的快速矿化，甲烷生成非常缓慢（∼1 μmol·天-1），滞后时间很长（>100 天），甲烷产率通常没有达到化学计量预期水平。然而，基因微阵列证实了所有地点都具有广泛的微生物功能的潜力，包括甲烷生成。当用丁酸盐（r = 0.98；p = 0.001）或戊酸盐（r = 0.84；p = 0.04）对库克湾的培养物进行修饰时，甲烷的生成速度相对较快，这一结果与功能基因微阵列中阳性 mcr 基因序列探针的数量显著相关，与原位检测到的 C4-C5 链烷酸一致。这一发现突出了共代谢在该地层中较软的褐煤和次烟煤生物降解中的作用，但在其他地层中较硬的次烟煤和烟煤中的甲烷生成则不那么明显。我们得出的结论是，煤甲烷生成可能不是由内在的缺乏代谢潜力、替代电子受体的存在或可用营养物质的缺乏所限制，而是更可能受到煤本身内在的难降解性的限制。
