一株Zn抗性菌株的筛选鉴定及吸附条件优化

Screening and identification of a heavy metal-resistant strain and optimization of its zinc biosorption conditions

采用浓度梯度法从铅锌尾矿区与污水灌溉区土壤中筛选了一株Zn抗性放线菌,并通过形态与培养特征、生理生化特性、细胞壁组分与16SrRNA基因序列分析对该菌株进行了鉴定.同时,综合运用单因素试验与正交试验法对该菌株吸附Zn2+的条件进行了优化.结果表明,菌株CCNWHX72-14经鉴定为高加索链霉菌(Streptomyces ciscaucasicus),其对Zn2+的抗性达到845mg·L-1.锌胁迫生长曲线表明,该菌株在130mg·L-1Zn2+胁迫时生长良好,且最适培养时间为7d.各个单因素条件对该菌株吸附Zn2+的影响顺序为:接种量>初始Zn2+浓度>初始pH>转速>温度.该菌株吸附Zn2+的最佳条件为:初始Zn2+浓度为150mg·L-1,初始pH=5,接种量为1%,转速为60r·min-1,温度为28℃.菌株CCNWHX72-14在最佳条件下对Zn2+的吸附较具有良好的重复性与稳定性,最高吸附量可达51.05mg·g-1,该研究为进一步探讨链霉菌的Zn2+吸附机制及其在生物修复中的应用奠定了基础.

We screened actinomycetes with heavy metal resistance and optimize the biosorption conditions of Zn^2＋ using concentration gradient methods. Morphological and cultural characteristics,physiological and biochemical properties,cell-wall pattern,and 16S rRNA gene sequence were used for identification. A heavy metal-resistant strain,designated CCNWHX 72-14,with resistance to 845 mg·L -1 of Zn^2＋ ,was isolated and identified as Streptomyces ciscaucasicu. It grew well in the presence of 130 mg·L -1 Zn^2＋ and the optimum culture time was 7 d. Both single factor and orthogonal experiments were designed to determine the optimum conditions for zinc biosorption and the order of each factors＇ effect was： inoculation dose initial Zn^2＋ concentration initial pH agitation speed temperature. The optimum conditions for zinc biosorption were： initial Zn^2＋ concentration 150 mg·L -1,initial pH 5,1% inoculation dose,60 r·min -1 and 28 ℃. The strain grew well with good repeatability and stability under the optimum conditions,and the maximum biosorption capacity of CCNWHX 72-14 under the experimental conditions reached 51. 05 mg·g^ -1. The present research has laid a foundation for further investigation into the zinc biosorption mechanism of this strain and its application in environmental bioremediation.