化能自养硫氧化细菌Halothiobacillus diazotrophicus低氧硫氧化特性及其机制
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国家自然科学基金(91951118)


Characteristics and mechanism of sulfur oxidation of Halothiobacillus diazotrophicus exposed to low oxygen
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    【目的】 探究Halothiobacillus diazotrophicus LS2在不同氧浓度下的硫氧化特性,并揭示其低氧适应机制。【方法】 通过离子色谱测定S2O32-和SO42-浓度,平板稀释涂布法跟踪测定菌体生长情况,转录组测序及生物信息学分析其差异表达基因及相关代谢通路。【结果】 菌株LS2在氧含量0.2%-21%的条件下能够进行硫氧化代谢和生长,并且在氧含量高于1.6%的条件下维持较高的硫氧化活性。比较转录组学分析筛选出851个可能与低氧适应相关的差异表达基因,包括表达上调基因464个,表达下调基因387个,其中硫代硫酸盐硫转移酶(thiosulfate sulfurtransferase, TST)、硫氧化酶/还原酶(sulfur oxidase/reductase, SOR)、硫化物:醌氧化还原酶(sulfide:quinone oxidoreductase, SQR)上调表达,Sox酶系下调表达,菌株LS2低氧硫氧化代谢途径可能发生改变。低氧组菌株LS2上调表达cbb3型细胞色素c氧化酶,以增加O2与酶的结合效率,同时上调表达固氮酶基因nifDKH和Fix复合体基因fixAfixBfixCfixX,利用N2、CO2为最终电子受体维持胞内氧化还原平衡。【结论】 菌株LS2是一株在低氧环境中仍能维持较高硫氧化活性的硫氧化细菌,SQR、高氧亲和末端氧化酶及固氮酶对其适应低氧环境有重要作用,本研究对丰富低氧硫氧化代谢机制认识有积极意义,为优化含硫废水处理工艺提供一定理论基础。

    Abstract:

    [Objective] To study the sulfur oxidation characteristics of Halothiobacillus diazotrophicus LS2 under different oxygen levels and to decipher the mechanism of strain LS2 adapting to low-oxygen environments. [Methods] The concentrations of S2O32- and SO42- were measured by ion chromatography. Bacterial growth was determined by plate dilution coating method. The differentially expressed genes and related metabolic pathways were identified and analyzed by transcriptome sequencing and bioinformatics technology. [Results] Strain LS2 oxidized reduced sulfur compounds and grew under 0.2%-21.0% oxygen, and it maintained high sulfur oxidation activity under the oxygen level above 1.6%. Comparative transcriptomic analysis screened out 851 differentially expressed genes that might be related to the adaptation to low oxygen, including 464 up-regulated genes and 387 down-regulated genes. In sulfur metabolism, thiosulfate sulfurtransferase, sulfur oxidase/reductase, and sulfide:quinone oxidoreductase were up-regulated, while the Sox enzyme system was down-regulated, which indicated that strain LS2 might change the sulfur oxidation pathway to adapt to low-oxygen environment. In the low-oxygen group, the cbb3-type cytochrome c oxidase was up-regulated to increase the O2-binding efficiency. Meanwhile, since less electron could be received by O2, the nitrogenase genes nifDKH and Fix complex genes fixA, fixB, fixC, fixX were up-regulated, making N2 and CO2 the alternative electron accepters to maintain redox balance, which explained the higher maximum bacterial growth in low-oxygen environments. [Conclusion] Strain LS2 is a sulfur-oxidizing bacterium that can maintain high sulfur oxidation activity in the low-oxygen environment. Sulfide:quinone oxidoreductase, high-oxygen-affinity terminal oxidases, and nitrogenase play a role in the adaptation to the low-oxygen environment. This study is of positive significance for deciphering the mechanism of sulfur oxidation under low oxygen and provides a theoretical basis for optimizing the treatment process of sulfur-containing wastewater.

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严洪珊,林炜铁,罗剑飞. 化能自养硫氧化细菌Halothiobacillus diazotrophicus低氧硫氧化特性及其机制. 微生物学报, 2024, 64(11): 4358-4370

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  • 收稿日期:2024-06-05
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  • 在线发布日期: 2024-10-30
  • 出版日期: 2024-11-04
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