Sprenger Wander W, Hackstein Johannes H P, Keltjens Jan T
Department of Microbiology, Faculty of Science, Radboud University of Nijmegen, Nijmegen, The Netherlands.
Antonie Van Leeuwenhoek. 2005 May;87(4):289-99. doi: 10.1007/s10482-004-5941-5.
Methanomicrococcus blatticola, a methanogenic archaeon isolated from the cockroach Periplaneta americana, is specialised in methane formation by the hydrogen-dependent reduction of methanol, monomethyl-, dimethyl- or trimethylamine. Experiments with resting cells demonstrated that the capability to utilise the methylated one-carbon compounds was growth substrate dependent. Methanol-grown cells were incapable of methylamine conversion, while cells cultured on one of the methylated amines did not metabolise methanol. Unlike trimethylamine, monomethyl- and dimethylamine metabolism appeared to be co-regulated. The central reaction in the energy metabolism of all methanogens studied so far, the reduction of CoM-S-S-CoB, was catalysed with high specific activity by a cell-free system. Activity was associated with the membrane fraction. Phenazine was an efficient artificial substrate in partial reactions, suggesting that the recently discovered methanophenazine might act in the organism as the physiological intermediary electron carrier. Our experiments also showed that M. blatticola apparently lacks the pathway for methyl-coenzyme oxidation to CO2, explaining the strict requirement for hydrogen in methanogenesis and the obligately heterotrophic character of the organism.
从美洲大蠊中分离出的产甲烷古菌——蟑螂甲烷微球菌，专门通过依赖氢气还原甲醇、一甲胺、二甲胺或三甲胺来生成甲烷。对静息细胞的实验表明，利用甲基化一碳化合物的能力取决于生长底物。以甲醇培养的细胞无法进行甲胺转化，而在甲基化胺之一上培养的细胞则不能代谢甲醇。与三甲胺不同，一甲胺和二甲胺的代谢似乎是共同调节的。到目前为止，在所有研究的产甲烷菌的能量代谢中，CoM-S-S-CoB的还原这一核心反应由无细胞系统以高比活性催化。活性与膜部分相关。吩嗪在部分反应中是一种有效的人工底物，这表明最近发现的甲烷吩嗪可能在生物体中作为生理中间电子载体起作用。我们的实验还表明，蟑螂甲烷微球菌显然缺乏甲基辅酶氧化为二氧化碳的途径，这解释了产甲烷过程中对氢气的严格需求以及该生物体严格的异养特性。
