Cu^2+胁迫对Acidithiobacillus ferrooxidans亚铁氧化代谢及胞外电子传递影响  

Effects of Cu^2+stress on ferrous oxidation metabolism and extracellular electron transfer of Acidithiobacillus ferrooxidans

作　　者：仉丽娟 吴平 王志杰 周文博[2] 周洪波[2] ZHANG Li-juan;WU Ping;WANG Zhi-jie;ZHOU Wen-bo;ZHOU Hong-bo(Faculty of Biotechnology and Pharmaceutical Engineering,Nanjing University of Technology,Nanjing 211816,China;Key Laboratory of Biometallurgy,Ministry of Education,School of Minerals Processing and Bioengineering,Central South University,Changsha 410083,China)

机构地区：[1]南京工业大学生物与制药工程学院,南京211816 [2]中南大学资源加工与生物工程学院生物冶金教育部重点实验室,长沙410083

出　　处：《中国有色金属学报》2019年第12期2868-2876,共9页The Chinese Journal of Nonferrous Metals

基　　金：江苏省高等学校自然科学研究面上项目(18KJB450001);江苏省博士后科研资助计划项目(1701136B);中国博士后科学基金资助项目(2018M632298);。

摘　　要：为了查明Cu^2+胁迫影响Acidithiobacillus ferrooxidans(At.ferrooxidans)亚铁氧化代谢机制,本研究设计了由低到高Cu^2+浓度(0~25 g/L)胁迫环境,利用邻菲啰啉分光光度法、实时荧光定量PCR和循环伏安法等分析手段分别探究了不同Cu^2+浓度胁迫下At.ferrooxidans亚铁氧化率、亚铁氧化电子传递链rus operon相关基因表达及胞外电子传递的响应情况。结果表明:Cu^2+胁迫浓度由0 g/L增加至25 g/L时,At.ferrooxidans菌亚铁氧化活性显著降低(25 g/L Cu^2+,对应下24 h亚铁氧化抑制率约为50%),rus operon相关基因表达显著下调(尤其是细胞内膜蛋白编码基因Cyc1和细胞色素c氧化酶编码基因CoxBACD分别下调12.4倍和4~6倍),Fe2+氧化胞外传递电子能力也降低(循环伏安曲线还原峰值29.0μA(对照组,0 g/L Cu^2+)和26.5μA(25 g/L Cu^2+))。综上所述,高浓度Cu^2+胁迫引起At.ferrooxidans菌亚铁氧化代谢Rus operon相关基因表达显著下调,造成胞外电子传递速率降低,最终导致At.ferrooxidans菌亚铁氧化率降低。The effects of Cu^2+stress(0?25 g/L)on the ferrous oxidation efficiency,expression of Rus operon genes and extracellular electron transfer of Acidithiobacillus ferrooxidans(At.ferrooxidans)were investigated by using phenanthroline spectrophotometry,real-time quantitative PCR and cyclic voltammetry.The obtained results indicate that the increased concentrations of Cu^2+stress from 0 g/L to 25 g/L inhibit the ferrous oxidation activity of At.ferrooxidans.Under the stress of 25 g/L Cu^2+,the 24 h ferrous oxidation inhibition efficiency is about 50%in comparison to the control(0 g/L Cu^2+).The high concentration of Cu^2+stress also decreases the transcriptional levels of Rus operon genes.Especially,Cyc1 and CoxBACD are decreased by 12.4 fold and 4?6 fold,respectively.Meanwhile,the decreased rate of extracelluler electron transfer in At.ferrooxidans under the stress of 25 g/L Cu^2+(26.5μA)is found in comparison to that in the control(0 g/L Cu^2+,29.0μA).In conclusion,the high concentration of Cu^2+stress results in the down-regulated expression of Rus operon genes related to Fe2+oxidation,afterwards inhibiting the electron transport from Fe2+oxidation,and finally leading to a decrease in the rate of ferrous oxidation.

关 键 词：ACIDITHIOBACILLUS ferrooxidans 重金属胁迫 亚铁氧化代谢 胞外电子传递 

分 类 号：Q939.97[生物学—微生物学]