响应面分析法优化沙雷氏菌(Serratia sp.) AXJ-M对己烯雌酚的降解

Degradation of diethylstilbestrol by Serratia sp. AXJ-M was optimized by Response Surface Methodology

摘要:

[背景] 环境雌激素已成为目前干扰人类和动物内分泌系统而影响健康和生殖的一类新型环境污染物，利用微生物的降解作用修复被其污染的环境具有重要的现实意义。[目的] 以实验室保藏的一株己烯雌酚（Diethylstilbestrol，DES）降解菌沙雷氏菌（Serratia sp.） AXJ-M为对象，开展其对DES的降解特性及降解条件优化的实验研究。[方法] 利用单因素试验、Plackett-Burman因素筛选、最陡爬坡试验和Box-Behnken设计相结合的方法优化Serratia sp.AXJ-M对DES的降解条件。[结果] （NH₄）₂SO₄、ZnCl₂、胰蛋白胨被分别选做无机氮源、额外金属离子和外加营养物质时，对DES降解有明显的促进作用。利用Plackett-Burman实验确定（NH₄）₂SO₄浓度、DES浓度、pH值为影响菌株AXJ-M降解DES的主要因素。在此基础上，采用最陡爬坡试验和Box-Behnken设计，确定菌株AXJ-M在（NH₄）₂SO₄浓度1.48 g/L、ZnCl₂浓度0.02 g/L、温度30℃、pH 7.19、DES浓度119.5 mg/L、接种量3%（体积分数）下培养7 d，菌株AXJ-M对DES的降解率达到76.89%，较未优化前提高了17.38%。[结论] Serratia sp.AXJ-M具有较高的DES降解能力，该菌可为生物修复受DES或其他人工合成雌激素污染的环境提供优良的微生物资源。

Abstract:

[Background] Environmental estrogens, major components in the new types of environmental pollutants, threaten the health of humans and animals by their adverse effect on the functions of the endocrine system. Microbial degradation is considered an efficient method in the removal of estrogenics and the bioremediation of polluted environments. [Objective] To improve diethylstilbestrol (DES) biodegradation efficiency, we studied the degradation characteristics of a DES-degrading bacterium Serratia sp. AXJ-M. [Methods] The degradation conditions of DES by Serratia sp. AXJ-M were optimized by performing the single factor test, Plackett-Burman test, steepest ascent hill climb test, and Box-Behnken test. [Results] Application of (NH₄)₂SO₄, ZnCl₂, and tryptone as inorganic nitrogen sources, additional metal ions, and added nutrients, respectively, significantly promoted the degradation of DES. The concentration of ammonium sulfate and DES and pH value were selected as the key parameters affecting the degradation of DES by performing the Plackett-Burman experiment. Box-Behnken experiment design and response surface methodology (RSM) analysis were adopted, the optimized conditions were (NH₄)₂SO₄ 1.48 g/L, ZnCl₂ 0.02 g/L, culture temperature 30℃, pH 7.19, DES 119.5 mg/L, and inoculation biomass 3%. The degradation rate of DES under these conditions reached 76.89% within 7 d, which was 17.38% higher than initial conditions. [Conclusion] Serratia sp. AXJ-M, a highly efficient DES degrading strain, can be used as an excellent microbial resource for bioremediation of the environment polluted by DES or other synthetic estrogens.