Sustainable carbon cycle toward mitigation of carbon dioxide emission and regeneration of hydrocarbon resources

二氧化碳捕获与封存（CCS）是减少大气中二氧化碳净排放量的可行技术选择之一。但是，对于滞留期、泄漏CO2等不确定性参数的研究还有待进一步深入。为了建立可持续的碳循环，需要开发能够将CCS储存在地下的二氧化碳转化为可重复使用的能源的碳转化工艺。利用微生物法对甲烷气池进行再生是解决这一问题的技术选择之一。本研究的目的是评估二氧化碳对混合培养系统的影响，通过添加以产氢物代谢物为底物的产甲烷细菌来提高甲烷产量，并为混合培养系统积累知识，为未来的建模做准备。在HYH-1与热石营养菌混合培养中，co2气相的甲烷产量是氮气气相的1.6倍。结果表明，乙酸发酵获得了更多的底物，这是最合适的产氢途径。接下来，为了提高甲烷产量，在培养物中加入了一种产甲烷细菌，这种细菌可以吸收醋酸，醋酸是产氢细菌的主要代谢物。在两种混合培养中加入一种醋酸同化细菌，嗜热甲烷菌，甲烷产量增加到1.5倍。为了从地下封存的二氧化碳中回收能量，研究了酸性、底物和营养限制条件对氢营养化产甲烷菌产甲烷的地球化学影响，以油藏中提取的两种地层水为介质，在模拟深盐水含水层的原位条件下研究了热自养甲烷菌产甲烷的影响。在特定培养基中厌氧生长的热自养甲烷杆菌的甲烷体积产率在pH5.5时比pH8.0时低2倍，在低pH条件下与两种地层水作为生长介质的营养限制条件相结合，甲烷体积产率显著降低，但仍保持1.5%的产量。少

Carbon dioxide capture and storage (CCS) is one of the feasible technological options for reducing net CO2emissions to the atmosphere. However, further studies on uncertainty parameter such as detention period and leakage CO2 are required toward the practical use. In order to establish sustainable carbon cycle, dPevelopment of carbon conversion processes capable of converting CO2 stored in subsurface by CCS into reusable sources of energy is desired. Regeneration of methane gas pool using microbial processes is thought to be one of the technical options addressing for this issue.The objectives of the study are to assess the effect of carbon dioxide on the mixed culture system, to increase methane yield by adding methane-producing bacteria that utilize metabolites of hydrogen-producer as substrates, and to accumulate knowledge in the mixed culture system with a view of future modeling. In the mixed culture of HYH-1 and M. thermolithotrophicus, methane production with carbon dioxide gas … More phase was 1.6-fold of that with nitrogen gas-phase. The result showed that more substrate becomes available for acetic acid fermentation, which is the most appropriate pathway for hydrogen production. Next, a methane-producing bacterium that assimilates acetic acid, a main metabolite of hydrogen-producing bacteria, was added to the culture in order to improve methane yield. Methane production increased to 1.5-fold by adding an acetic acid assimilating bacterium, Methanosarcina thermophila, to the two-species mixed culture.For recovering energy from carbon dioxide sequestrated in subsurface, geochemical effects of acidic and substrate- and nutrient-limiting conditions on methane production by a hydrogenotrophic methanogen Methanothermobacter thermautotrophicus were investigated under simulated in situ conditions of deep saline aquifers using two formation waters retrieved from petroleum reservoirs as medium. Volumetric production rate of methane by anaerobically growing Methanothermobacter thermautotrophicus cells in a defined medium was 2-fold lower at pH5.5 than at pH8.0 and was significantly reduced but still retained 1.5% of productivities at the low pH in combination with nutrient-limiting conditions employing two formation waters as growth media. Less