Shewanella oneidensis MR-1对Cr(Ⅵ)的还原及其影响因素
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摘要
在实验室纯培养条件下,探讨厌氧体系中Shewanella oneidensis MR-1对Cr(Ⅵ)的还原能力,采用扫描电镜(SEM)-能谱(EDS)、X射线光电子能谱(XPS)等方法进行表征.结果表明,S.oneidensis MR-1介导下不同浓度Cr(Ⅵ)的生物转化与微生物对铬的耐受特性密切相关,低浓度Cr(Ⅵ)对其生长影响不大,高浓度时细菌生长则受到抑制,进而抑制Cr(Ⅵ)的还原率;菌株对Cr(Ⅵ)的还原作用随着接种菌悬液量的增加而增强;菌株最适生长p H值为中性,弱碱性环境比酸性环境更有利于菌株对Cr(Ⅵ)的还原;增加Fe(III)的量会加快Cr(Ⅵ)完全还原的速率.通过SEM-EDS和XPS分析,在对Cr(Ⅵ)进行处理5d后,菌体表面有Cr(Ⅵ)和Cr(III)两种形态存在,证实S.oneidensis MR-1在对Cr(Ⅵ)进行还原的同时也伴有少量的吸附作用.微生物还原为环境中Cr(Ⅵ)的去除以及解毒提供了一种有效的方法.
The ability of Shewanella oneidensis MR-1 to reduce Cr(VI) was investigated by pure culture under anaerobic condition in laboratory. The characterics of Cr(VI) reduction by S. oneidensis MR-1 was studied by scanning electron microscopy(SEM) equipped with an energy dispersive spectrometer(EDS) and X-ray photoelectron spectroscopy(XPS). The results showed that the bioreduction of Cr(VI) at different initial concentrations was closely related to the tolerance of bacterial strains to chromium. Cr(VI) at low concentration had little effect on the strains growth. Cell growth was inhibited at high Cr(VI) concentration, thereby inhibiting the reduction of Cr(VI). The reduction of Cr(VI) increased with increasing the amount of strains inoculum. The optimum p H of the strains growth was neutral, and the weakly alkaline environment was more conducive to the Cr(VI) reduction than the acidic environment. The increasing amount of Fe(III) accelerated the rate at which Cr(VI) was completely reduced. The results of SEM-EDS and XPS analysis showed that Cr(VI) and Cr(III) existed on the surface of cells after treatment with Cr(VI) for 5 days, which confirmed that Cr(VI) reduction by S. oneidensis MR-1 was at the same time also accompanied by a small amount of Cr(VI) adsorption. Microbial reduction provides an effective method for the removal and detoxification of Cr(VI) in the environment.
The ability of Shewanella oneidensis MR-1 to reduce Cr(VI) was investigated by pure culture under anaerobic condition in laboratory. The characterics of Cr(VI) reduction by S. oneidensis MR-1 was studied by scanning electron microscopy(SEM) equipped with an energy dispersive spectrometer(EDS) and X-ray photoelectron spectroscopy(XPS). The results showed that the bioreduction of Cr(VI) at different initial concentrations was closely related to the tolerance of bacterial strains to chromium. Cr(VI) at low concentration had little effect on the strains growth. Cell growth was inhibited at high Cr(VI) concentration, thereby inhibiting the reduction of Cr(VI). The reduction of Cr(VI) increased with increasing the amount of strains inoculum. The optimum p H of the strains growth was neutral, and the weakly alkaline environment was more conducive to the Cr(VI) reduction than the acidic environment. The increasing amount of Fe(III) accelerated the rate at which Cr(VI) was completely reduced. The results of SEM-EDS and XPS analysis showed that Cr(VI) and Cr(III) existed on the surface of cells after treatment with Cr(VI) for 5 days, which confirmed that Cr(VI) reduction by S. oneidensis MR-1 was at the same time also accompanied by a small amount of Cr(VI) adsorption. Microbial reduction provides an effective method for the removal and detoxification of Cr(VI) in the environment.
引文
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[2]郑礼胜,王士龙,张虹,等.用沸石处理含铬废水的试验研究[J].环境工程,1997,15(3):13-15.
[3]王国惠.板栗壳对重金属Cr(VI)吸附性能的研究[J].环境工程学报,2009,3(5):791-794.
[4]Cheung K H,Gu J D.Mechanism of hexavalent chromium detoxification by microorganisms and bioremediation application potential:A review[J].International Biodeterioration and Biodegradation,2007,59(1):8-15.
[5]Dresel P E,Wellman D M,Cantrell K J,et al.Review:Technical and policy challenges in deep vadose zone remediation of metals and radionuclides[J].Environmental Science&Technology,2011,45:4207-4216.
[6]Viamajala S,Peytonb M,Sani R K,et al.Toxic effects of chromium(VI)on anaerobic and aerobic growth of Shewanella oneidensis MR-1[J].Biotechnology Progress,2004,20(1):87-95.
[7]汪明霞,王娟,司友斌,等.Shewanella oneidensis MR-1异化还原Fe(Ⅲ)介导的As(Ⅲ)氧化转化[J].中国环境科学,2014,34(9):2368-2373.
[8]李斗,赵由才,宋立岩,等.六价铬细菌还原的分子机制研究进展[J].环境科学,2014,35(4):1602-1612.
[9]Tang Y J,Laidlae D,Gani K,et al.Evaluation of the effects of various culture conditions on Cr(VI)reduction by Shewanella oneidensis MR-1in a novel high-throughput mini-bioreactor[J].Biotechnology and Bioengineering,2006,95(1):176-184.
[10]Myers C R,Carstens B P,Antholine W E,et al.Chromium(VI)reductase activity is associated with the cytoplasmic membrane of anaerobically grown Shewanella putrefaciens MR-1[J].Journal of Applied Microbiology,2000,88(1):98-106.
[11]Urvashi T,Datta M.Reduction of toxic chromium and partial localization of chromium reductase activity in bacterial isolate DM1[J].World Journal of Microbiology&Biotechnology,2005,21(6/7):891-899.
[12]Middleton S S,Latmani R B,Mackey M R,et al.Cometabolism of Cr(VI)by Shewanella oneidensis MR-1produces cell-associated reduced chromium and inhibits growth[J].Biotechnology and Bioengineering,2003,83(6):634-635.
[13]Fu L,Li S W,Ding Z W,et al.Iron reduction in the DAMO/Shewanella oneidensis MR-1coculture system and the fate of Fe(II)[J].Water Research,2016,88:808-815.
[14]Schaefer JK,Rocks SS,Zheng W,et al.Active transport,substrate specificity,and methylation of Hg(II)in anaerobic bacteria[J].Proceedings of the National Academy of Sciences of the United States of America,2011,108:8714-8719.
[15]Yuan ZH,Li JW,Li C,et al.Interaction of silver nanoparticles with pure nitrifying bacteria[J].Chemosphere,2013,90:1404-1411.
[16]汤洁.Fe-微生物协同去除水中Cr(VI)的研究[D].浙江:浙江大学,2013.
[17]王娟.Shewanella oneidensis MR-1对砷甲基化及其影响因素研究[D].安徽:安徽农业大学,2014.
[18]李松.水稻土中异化铁还原对Cr(VI)[D].陕西:西北农林大学,2006.
[19]Xia S Q,Zhou L J,Zhang Z Q,et al.Removal mechanism of low-concentration Cr(VI)in a submerged membrane bioreactor activated sludge system[J].Applied Microbiology and Biotechnology,2015,99(12):5351-5360.
[20]王娟,韩涛,司友斌,等.Shewanella oneidensis MR-1对不同价态砷的生物转化与甲基化[J].中国环境科学,2015,35(11):3396-3402.
[21]Yuan Z H,Li J W,Li C,et al.Interaction of silver nanoparticles with pure nitrifying bacteria[J].Chemosphere,2013,90(4):1404-1411.
[22]Tian X,Wang W W,Tian N,et al.Cr(VI)reduction and immobilization by novel carbonaceous modified magnetic Fe3O4/halloysite nanobrid[J].Journal of Hazardous Materials,2016,309:151-156.
[23]Yu Z H,Zhang X D,Huang Y M,et al.Magnetic chitosan-iron(III)hydrogel as a fast and reusable adsorbent for chromium(VI)removal[J].Industrial Engineering Chemistry Research,2013,52(40):11956-11966.
[24]Ai Z H,Cheng Y,Zhang L Z,et al.Efficient removal of Cr(VI)from aqueous solution with Fe@Fe2O3core-shell nanowires[J].Environmental Science&Technology,2008,42(18):6955-6960.