Products of trace methane oxidation during nonmethyltrophic growth by Methanosarcina
Products of trace methane oxidation during nonmethyltrophic growth by Methanosarcina
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DOI：
10.1029/2006jg000268
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发表时间：
2007-06
影响因子：
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通讯作者：
J. Moran;C. House;B. Thomas;K. Freeman
中科院分区：
文献类型：
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作者：
J. Moran;C. House;B. Thomas;K. Freeman
[1]我们对甲烷厌氧氧化（AOM）中所涉及的代谢途径的理解受到了没有分离的厌氧甲烷氧化菌的挑战。幸运的是，痕量甲烷氧化（TMO）是由与厌氧甲烷氧化菌密切相关的孤立生物进行的。由于TMO可能与AOM代谢有相似之处，因此在培养实验中对TMO的研究可以增强我们对AOM的理解。在这里，我们探讨了TMO的乙酸甲烷八叠球菌分别生长在乙酸和一氧化碳的文化。在乙酸盐上生长的培养物中，我们没有观察到甲烷氧化成二氧化碳，但确实观察到甲烷氧化成乙酸盐（1.1 x 10 - 6 ± 3.5 x 10 - 8摩尔的CH 4氧化，0.10%的CH 4产生）。甲烷只转化为甲基。由于AOM脂质在自然界中表现出强烈的13 C耗尽，我们的研究结果意味着乙酸盐作为AOM中间体并不起主要作用。一氧化碳培养物显示很少或没有甲烷转化为二氧化碳（1.9 x 10 - 7 ± 2.0 x 10 - 7摩尔甲烷氧化），中度甲烷氧化为乙酸盐（1.8 × 10 - 7 ± 7.3 × 10 - 8摩尔氧化甲烷，0.14%的生物甲烷产量），甲烷转化为产物甲基硫醚的甲基的转化率高（4.0 × 10 - 6 ± 7.7 × 10 - 7摩尔氧化甲烷，占生物甲烷产量的3.1%）。两者合计，我们的研究结果确定甲基硫化物更可能在天然AOM比乙酸的中间体。
[1] Our understanding of the metabolic pathways involved in the anaerobic oxidation of methane (AOM) is challenged by not having an isolated anaerobic methanotroph. Fortunately, trace methane oxidation (TMO) is carried out by isolated organisms closely related to anaerobic methanotrophs. As TMO likely shares metabolic similarities with the AOM metabolism, studies of TMO in culture experiments can serve to enhance our understanding of AOM. Here we explored TMO in cultures of Methanosarcina acetivorans grown separately on acetate and carbon monoxide. We observed no methane oxidation to carbon dioxide in the cultures grown on acetate, but did observe methane oxidation to acetate (1.1 x 10 -6 ± 3.5 x 10 -8 moles CH 4 oxidized, 0.10% of the CH 4 produced). Methane was exclusively converted to the methyl position. Because AOM lipids exhibit strong 13 C depletion in nature, our results imply acetate does not play a major role as an AOM intermediate. The carbon monoxide cultures showed little or no methane conversion to carbon dioxide (1.9 x 10 -7 ± 2.0 x 10 -7 moles CH 4 oxidized), moderate methane oxidation to acetate (1.8 x 10 -7 ± 7.3 x 10 -8 moles CH 4 oxidized, 0.14% of biogenic CH 4 production), and high methane conversion to the methyl groups of product methyl sulfides (4.0 x 10 -6 ± 7.7 x 10 -7 moles CH4 oxidized, 3.1% of biogenic CH 4 production). Taken together, our results identify methyl sulfides as more likely intermediates in natural AOM than acetate.