外源硫酸盐对耐铬（VI）工程菌株铬（VI）代谢的影响。
Effects of exogenous sulfate on the chromium(VI) metabolism of chromium(VI)-resistant engineered strains.
作者信息
Li Xinglong, Yin Qi, Gu Ruijia, Li Mei, Yan Jing, Liu Yuan, Qiu Yanlun, Bai Qunhua, Li Yingli, Ji Yan, Gao Jieying, Xiao Hong
机构信息
Department of Health Laboratory Technology, School of Public Health and Management, Chongqing Medical University, No. 61 Daxuecheng Middle Road, Shapingba District, Chongqing 401334, PR China.
Department of Health Laboratory Technology, School of Public Health and Management, Chongqing Medical University, No. 61 Daxuecheng Middle Road, Shapingba District, Chongqing 401334, PR China; Center for Disease Control and Prevention of Fucheng District, No. 116 north section of Changhong Avenue, Fucheng District, Mianyang City 621000, PR China.
出版信息
Ecotoxicol Environ Saf. 2021 Nov 15;228:112984. doi: 10.1016/j.ecoenv.2021.112984.
OBJECTIVE
To explore the effects of exogenous sulfate on the efficiency of chromium(VI) metabolism of three chromium(VI)-resistant Escherichia coli strains (eChrA / eChrB / eChrAB) by adding chromium(VI)-resistance genes chrA and/or chrB, for better understanding and further application of these Cr(VI)-resistant strains in environmental and industrial chromium removal.
METHODS
Based on three engineered Cr(VI)-resistant strains exposed to different concentrations of sulfate: i) Evaluation of Cr(VI) metabolism characteristics, including the growth rate, the Cr(VI) tolerance, the removal, absorption and efflux capacity of Cr(VI); ii) Detection the expressions of Cr(VI) resistance-related genes (chrA and chrB), and sulfate channel protein-related genes (sbp, cysA, cysU and cysW genes) by RT-qPCR.
RESULTS
Exogenous sulfate enhanced the Cr(VI) tolerance and the removal rate of these three engineered Cr(VI)-resistant strains, and promoted their growth rate under Cr(VI) stress, while suppressed their absorption and efflux capacity. Under a certain sulfate concentration, the Cr(VI) tolerance, removal ability and efflux capacity of these three strains were ranked as follow: eChrAB > eChrA > eChrB, while ranked as eChrB > eChrA > eChrAB for the Cr(VI) absorption rate, respectively. Opposite to the Cr(VI) treatment, exogenous sulfate suppressed the transcription levels of the Cr(VI) resistance-related genes (chrA and chrB) with gradually increased concentrations, and reduced those of sulfate channel protein related genes (sbp,cysA, cysU and cysW) under the medium and high concentrations.
CONCLUSION
Sulfate can enhance the Cr(VI) tolerance and growth of Cr(VI)-resistant strains, via inhibiting the Cr(VI) absorption and efflux in a concentration-dependent manner. The underlying mode of action might be the competition of transport channels between sulfate and Cr(VI), and the suppression of sulfate channel protein related genes expressions by exogenous sulfate. Our results demonstrated an appropriate supplication of exogenous sulfate could contribute to the Cr(VI) pollution management by genes chrA/chrB related Cr(VI)-resistant strains. Additionally, the engineered E. coli strain eChrAB showed more potential for the actual Cr(VI) pollution application than strain eChrA and eChrB.
目的
通过添加铬（VI）抗性基因chrA和/或chrB，探讨外源硫酸盐对三株抗铬（VI）大肠杆菌菌株（eChrA / eChrB / eChrAB）铬（VI）代谢效率的影响，以便更好地理解这些抗铬（VI）菌株在环境和工业铬去除中的作用并进一步应用。
方法
基于三株工程化抗铬（VI）菌株暴露于不同浓度的硫酸盐：i）评估铬（VI）代谢特征，包括生长速率、铬（VI）耐受性、铬（VI）的去除、吸收和外排能力；ii）通过RT-qPCR检测铬（VI）抗性相关基因（chrA和chrB）以及硫酸盐通道蛋白相关基因（sbp、cysA、cysU和cysW基因）的表达。
结果
外源硫酸盐增强了这三株工程化抗铬（VI）菌株的铬（VI）耐受性和去除率，并在铬（VI）胁迫下促进了它们的生长速率，同时抑制了它们的吸收和外排能力。在一定硫酸盐浓度下，这三株菌株的铬（VI）耐受性、去除能力和外排能力排序如下：eChrAB > eChrA > eChrB，而铬（VI）吸收率排序为eChrB > eChrA > eChrAB。与铬（VI）处理相反，外源硫酸盐随着浓度逐渐增加抑制了铬（VI）抗性相关基因（chrA和chrB）的转录水平，并在中高浓度下降低了硫酸盐通道蛋白相关基因（sbp、cysA、cysU和cysW）的转录水平。
结论
硫酸盐可以通过浓度依赖性抑制铬（VI）的吸收和外排来增强抗铬（VI）菌株的铬（VI）耐受性和生长。潜在的作用方式可能是硫酸盐和铬（VI）之间运输通道的竞争，以及外源硫酸盐对硫酸盐通道蛋白相关基因表达的抑制。我们的结果表明，适当添加外源硫酸盐有助于通过与基因chrA/chrB相关抗铬（VI）菌株来管理铬（VI）污染。此外，工程化大肠杆菌菌株eChrAB在实际铬（VI）污染应用中比菌株eChrA和eChrB显示出更大的潜力。
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