化能自养硫氧化细菌Halothiobacillus diazotrophicus低氧硫氧化特性及其机制  

Characteristics and mechanism of sulfur oxidation of Halothiobacillus diazotrophicus exposed to low oxygen

作　　者：严洪珊 林炜铁[1] 罗剑飞[1] YAN Hongshan;LIN Weitie;LUO Jianfei(School of Biology and Biological Engineering,South China University of Technology,Guangzhou 510006,Guangdong,China)

机构地区：[1]华南理工大学生物科学与工程学院,广东广州510006

出　　处：《微生物学报》2024年第11期4358-4370,共13页Acta Microbiologica Sinica

基　　金：国家自然科学基金(91951118)。

摘　　要：【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(sulfuroxidase/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O_(2)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fixA、fixB、fixC、fixX,利用N_(2)、CO_(2)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。[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 O_(2)-binding efficiency.Meanwhile,since less electron could be received by O_(2),the nitrogenase genes nifDKH and Fix complex genes fixA,fixB,fixC,fixX were up-regulated,making N_(2) and CO_(2) 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

关 键 词：低氧适应 硫氧化细菌 固氮酶 末端氧化酶 转录组分析 

分 类 号：Q93[生物学—微生物学]