Evans P J, Ling W, Goldschmidt B, Ritter E R, Young L Y
Department of Microbiology, New York University Medical Center, New York 10016.
Appl Environ Microbiol. 1992 Feb;58(2):496-501. doi: 10.1128/aem.58.2.496-501.1992.
Strain T1 is a facultative bacterium that is capable of anaerobic toluene degradation under denitrifying conditions. While 80% of the carbon from toluene is either oxidized to carbon dioxide or assimilated into cellular carbon, a significant portion of the remainder is transformed into two dead-end metabolites. These metabolites were produced simultaneous to the mineralization of toluene and were identified as benzylsuccinic acid and benzylfumaric acid. Identification was based on comparison of mass spectra of the methyl esters of the metabolites and authentic compounds that were chemically synthesized. Strain T1 is also capable of o-xylene transformation during growth on toluene. o-Xylene does not serve as a source of carbon and is not mineralized. Rather, it is transformed to analogous dead-end metabolites, (2-methylbenzyl)-succinic acid and (2-methylbenzyl)-fumaric acid. o-Xylene transformation also occurred during growth on succinic acid, which suggests that attack of the methyl group by succinyl-coenzyme A is a key reaction in this transformation. We reason that the main pathway for toluene oxidation to carbon dioxide involves a mechanism similar to that for the formation of the metabolites and involves an attack of the methyl group of toluene by acetyl-coenzyme A.
菌株T1是一种兼性细菌，能够在反硝化条件下厌氧降解甲苯。虽然甲苯中80%的碳要么被氧化成二氧化碳，要么被同化为细胞碳，但其余的一大部分则转化为两种终产物代谢物。这些代谢物是在甲苯矿化的同时产生的，被鉴定为苄基琥珀酸和苄基富马酸。鉴定是基于代谢物甲酯的质谱与化学合成的标准化合物的质谱比较。菌株T1在以甲苯为生长底物时也能够转化邻二甲苯。邻二甲苯不是碳源，也不会被矿化。相反，它被转化为类似的终产物代谢物，即(2-甲基苄基)-琥珀酸和(2-甲基苄基)-富马酸。在以琥珀酸为生长底物时也发生了邻二甲苯的转化，这表明琥珀酰辅酶A对甲基的攻击是该转化过程中的关键反应。我们推断甲苯氧化成二氧化碳的主要途径涉及一种类似于代谢物形成的机制，并且涉及乙酰辅酶A对甲苯甲基的攻击。
