Subdepartment of Environmental Technology, Wageningen University, Wageningen, The Netherlands.
FEMS Microbiol Ecol. 2010 May;72(2):261-71. doi: 10.1111/j.1574-6941.2010.00849.x. Epub 2010 Feb 15.
This study investigates the oxidation of labeled methane (CH(4)) and the CH(4) dependence of sulfate reduction in three types of anaerobic granular sludge. In all samples, (13)C-labeled CH(4) was anaerobically oxidized to (13)C-labeled CO(2), while net endogenous CH(4) production was observed. Labeled-CH(4) oxidation rates followed CH(4) production rates, and the presence of sulfate hampered both labeled-CH(4) oxidation and methanogenesis. Labeled-CH(4) oxidation was therefore linked to methanogenesis. This process is referred to as trace CH(4) oxidation and has been demonstrated in methanogenic pure cultures. This study shows that the ratio between labeled-CH(4) oxidation and methanogenesis is positively affected by the CH(4) partial pressure and that this ratio is in methanogenic granular sludge more than 40 times higher than that in pure cultures of methanogens. The CH(4) partial pressure also positively affected sulfate reduction and negatively affected methanogenesis: a repression of methanogenesis at elevated CH(4) partial pressures confers an advantage to sulfate reducers that compete with methanogens for common substrates, formed from endogenous material. The oxidation of labeled CH(4) and the CH(4) dependence of sulfate reduction are thus not necessarily evidence of anaerobic oxidation of CH(4) coupled to sulfate reduction.
本研究调查了三种厌氧颗粒污泥中标记甲烷 (CH(4)) 的氧化和 CH(4) 对硫酸盐还原的依赖性。在所有样品中，(13)C 标记的 CH(4) 被厌氧氧化为 (13)C 标记的 CO(2)，同时观察到净内源 CH(4) 产生。标记-CH(4) 氧化速率随 CH(4) 产生速率而变化，而硫酸盐的存在阻碍了标记-CH(4) 氧化和产甲烷作用。因此，标记-CH(4) 氧化与产甲烷作用有关。这个过程被称为痕量 CH(4) 氧化，已在产甲烷纯培养物中得到证实。本研究表明，标记-CH(4) 氧化与产甲烷作用之间的比值受 CH(4) 分压的正向影响，并且在产甲烷颗粒污泥中的比值比产甲烷菌的纯培养物中的比值高 40 多倍。CH(4) 分压也对硫酸盐还原有正向影响，对产甲烷作用有负向影响：在升高的 CH(4) 分压下，产甲烷作用受到抑制，这为硫酸盐还原菌提供了优势，因为它们与产甲烷菌竞争来自内源性物质的共同底物。因此，标记 CH(4) 的氧化和 CH(4) 对硫酸盐还原的依赖性不一定是 CH(4) 与硫酸盐还原偶联的厌氧氧化的证据。
