Fachbereich Biologie, Universität Konstanz, Universitätsstr. 10, D-78457 Constance, Germany.
Appl Environ Microbiol. 2011 Jul;77(13):4429-36. doi: 10.1128/AEM.00340-11. Epub 2011 May 6.
Anaerobic oxidation of methane (AOM) with sulfate as terminal electron acceptor has been reported for various environments, including freshwater habitats, and also, nitrate and nitrite were recently shown to act as electron acceptors for methane oxidation in eutrophic freshwater habitats. Radiotracer experiments with sediment material of Lake Constance, an oligotrophic freshwater lake, were performed to follow 14CO2 formation from 14CH4 in sediment incubations in the presence of different electron acceptors, namely, nitrate, nitrite, sulfate, or oxygen. Whereas 14CO2 formation without and with sulfate addition was negligible, addition of nitrate increased 14CO2 formation significantly, suggesting that AOM could be coupled to denitrification. Nonetheless, denitrification-dependent AOM rates remained at least 1 order of magnitude lower than rates of aerobic methane oxidation. Using molecular techniques, putative denitrifying methanotrophs belonging to the NC10 phylum were detected on the basis of the pmoA and 16S rRNA gene sequences. These findings show that sulfate-dependent AOM was insignificant in Lake constant sediments. However, AOM can also be coupled to denitrification in this oligotrophic freshwater habitat, providing first indications that this might be a widespread process that plays an important role in mitigating methane emissions.
甲烷的厌氧氧化（AOM）与硫酸盐作为末端电子受体已在各种环境中得到报道，包括淡水生境，最近还表明硝酸盐和亚硝酸盐在富营养化的淡水生境中可以作为甲烷氧化的电子受体。利用来自贫营养淡水湖康斯坦茨湖的沉积物材料进行放射性示踪实验，在存在不同电子受体（即硝酸盐、亚硝酸盐、硫酸盐或氧气）的情况下，对沉积物培养物中 14CH4 形成 14CO2 进行了跟踪。虽然没有添加硫酸盐和添加硫酸盐的 14CO2 形成可以忽略不计，但添加硝酸盐可显著增加 14CO2 的形成，表明 AOM 可以与反硝化作用偶联。尽管如此，依赖于反硝化作用的 AOM 速率仍至少比好氧甲烷氧化速率低 1 个数量级。使用分子技术，根据 pmoA 和 16S rRNA 基因序列，检测到属于 NC10 门的假定的反硝化甲烷营养菌。这些发现表明硫酸盐依赖的 AOM 在康斯坦茨湖沉积物中并不重要。然而，在这种贫营养的淡水生境中，AOM 也可以与反硝化作用偶联，这首次表明这可能是一种广泛存在的过程，在减轻甲烷排放方面发挥着重要作用。
