化能自养硫氧化细菌Halothiobacillus sp.LS2介导的以乙炔为电子受体的硫氧化反应

Anaerobic sulfur oxidation with acetylene as electron acceptor mediated by chemoautotrophic sulfur-oxidizing bacterium Halothiobacillus sp. LS2

摘要:

[目的] 探究化能自养硫氧化细菌Halothiobacillus sp.LS2介导的以乙炔为电子受体的厌氧硫氧化反应。[方法] 稀释涂布法测定细胞生长情况，离子色谱仪测试硫氧化动力学中SO₄^2-和S₂O₃^2-以及基于相对荧光定量法的基因表达分析。[结果] 尽管菌株LS2在以氧气为电子受体时的最大反应速率V_max更高，但在厌氧条件下且以乙炔为电子受体时，菌株LS2的生长量是氧气为电子受体时的2倍，且硫氧化酶基因soxB的表达量显著高于氧气作为电子受体时。[结论] 菌株LS2不仅可以以乙炔为电子受体完成厌氧硫氧化反应，且这一代谢过程的产能效率较有氧硫氧化过程更高。本研究首次发现了微生物介导的以乙炔为电子受体的厌氧硫氧化反应，对丰富硫的生物地球化学循环理论有积极意义。

Abstract:

[Objective] The study aims to investigate the acetylene as electron acceptor anaerobic sulfur oxidation mediated by the chemoautotrophic sulfur oxidizing bacterium Halothiobacillus sp. LS2. [Methods] Cell growth was measured by dilution coating method, SO₄^2- and S₂O₃^2- in sulfur oxidation kinetics were measured by ion chromatograph, and gene expression was analyzed based on relative fluorescence quantitative method. [Results] Although strain LS2 obtained high maximum reaction rate V_max with O₂ as electron acceptor, its growth with acetylene as electron acceptor under anaerobic condition was twice that with O₂ as electron acceptor, and the expression of soxB gene was significantly higher than that with O₂ as electron acceptor. [Conclusion] These results indicated that strain LS2 can not only complete anaerobic sulfur oxidation with acetylene as electron acceptor, but also has higher productivity efficiency than aerobic sulfur oxidation. In this study, an anaerobic sulfur oxidation reaction using acetylene as electron acceptor was proposed for the first time, which is of positive significance to the sulfur biogeochemical cycle.