美国俄亥俄州立大学F. Robert Tabita及其团队发现固氮酶样酶体系催化产生蛋氨酸、乙烯和甲烷。相关论文于2020年8月28日发表在《科学》杂志上。

研究人员发现陆地和淡水细菌产生的甲烷和乙烯是由以前未知的蛋氨酸生物合成途径直接产生的。该途径存在于许多物种中，使用不同于已知固氮酶的固氮酶样还原酶，并在C–S键断裂中起特定作用以减少普遍存在且相当可观的挥发性有机硫化合物，例如二甲基硫醚和（2 -甲硫基）乙醇。该过程产生的甲硫醇是甲硫氨酸的直接前体，而乙烯或甲烷则释放到环境中。

通过这种途径产生的厌氧乙烯显然可以解释长期以来在缺氧土壤中观察到的乙烯积累现象。甲烷的产生揭示了不同于古细菌甲烷生成的另一条细菌途径。

研究人员表示，细菌生产的气态碳氢化合物（例如乙烯和甲烷）会影响土壤环境和气候。

附：英文原文

Title: A nitrogenase-like enzyme system catalyzes methionine, ethylene, and methane biogenesis

Author: Justin A. North, Adrienne B. Narrowe, Weili Xiong, Kathryn M. Byerly, Guanqi Zhao, Sarah J. Young, Srividya Murali, John A. Wildenthal, William R. Cannon, Kelly C. Wrighton, Robert L. Hettich, F. Robert Tabita

Issue&Volume: 2020/08/28

Abstract: Bacterial production of gaseous hydrocarbons such as ethylene and methane affects soil environments and atmospheric climate. We demonstrate that biogenic methane and ethylene from terrestrial and freshwater bacteria are directly produced by a previously unknown methionine biosynthesis pathway. This pathway, present in numerous species, uses a nitrogenase-like reductase that is distinct from known nitrogenases and nitrogenase-like reductases and specifically functions in C–S bond breakage to reduce ubiquitous and appreciable volatile organic sulfur compounds such as dimethyl sulfide and (2-methylthio)ethanol. Liberated methanethiol serves as the immediate precursor to methionine, while ethylene or methane is released into the environment. Anaerobic ethylene production by this pathway apparently explains the long-standing observation of ethylene accumulation in oxygen-depleted soils. Methane production reveals an additional bacterial pathway distinct from archaeal methanogenesis.

DOI: 10.1126/science.abb6310

Source: https://science.sciencemag.org/content/369/6507/1094