应用单针注射等温微量量热滴定法检测尿素水解菌对Hg2+的耐受性

Resistance of urea hydrolytic bacteria to Hg2+ probed by single injection isothermal titration calorimetry

摘要:

【目的】利用单针注射等温微量量热滴定法(SIITC)检测尿素水解菌对Hg2+的耐受性。【方法】与传统的细胞生长曲线法和基于尿素水解的pH变化曲线相对比，应用SIITC研究耐盐尿素水解菌Staphylococcus succinus对不同浓度Hg2+的耐受性，通过相关性分析验证SIITC检测细菌对重金属胁迫耐受性的可行性。【结果】S. succinus菌吸附水解尿素的最大热量交换速率和累积热量值随Hg2+浓度升高而降低。最大热量交换速率由不含Hg2+的?45 μJ/s降至10 μmol/L Hg2+处理的?20 μJ/s，吸收热量由?1 291.90 μJ下降到?535.75 μJ；不同浓度Hg2+胁迫下S. succinus菌吸附水解尿素的反应热量值与溶液pH以及OD600的相关系数r分别达到0.928和0.955。【结论】SIITC可用来检测Hg2+对尿素水解菌S. succinus的毒性。

关键词:尿素水解菌，重金属，生物修复，毒性检测，单针注射等温微量量热滴定法

Abstract:

[Objective] To determine the resistance of urea hydrolytic bacteria to Hg2+ using single injection isothermal titration calorimetry (SIITC). [Methods] The tolerance of urea hydrolytic bacterium Staphylococcus succinus to Hg2+ toxicity was assessed by SIITC in comparison with the traditional cell growth curves and pH change curves. The correlation between SIITC and the traditional methods was examined. [Results] The maximum heat flux rate and the accumulated heat of adsorption and hydrolysis of urea by S. succinus decreased with increasing Hg2+ concentration up to 10 μmol/L. The maximum heat flux rate decreased from ?45 μJ/s for the control to ?20 μJ/s for 10 μmol/L Hg2+ treated cells and the accumulated heat decreased from ?1 291.90 μJ for the control to ?535.75 μJ for 10 μmol/L Hg2+ treated cells. The decreases of heat flux rate and accumulated heat well correlated with the change of solution pH (r=0.928) and cell growth rate OD600 (r=0.955). [Conclusion] SIITC is a potential method to detect tolerance of bacteria to Hg2+.

Key words:Urea hydrolytic bacteria, heavy metals, bioremediation, toxicity test, single injection isothermal titration calorimetry