一株耐As细杆菌对As3+的吸附特征与机理

【目的】评价细杆菌属去除水溶液中As^3+的可行性,为As污染的微生物修复提供必要的修复材料和理论依据。【方法】从湖南某矿区筛选分离等得到了一株高耐砷菌株,经过16S rRNA序列分析初步鉴定为细杆菌属Microbacterium,命名为A4,并采用单因素试验优化菌株生长条件,正交试验优化菌株菌粉吸附As^3+的条件。通过吸附动力学与等温吸附试验研究菌株菌粉对As^3+的吸附特征,并利用SEM-EDX与FTIR分析探讨了该菌株菌粉对As^3+的吸附机理。【结果】菌株A4对As^3+的耐受阈值为53 mmol/L;菌株A4的最适生长条件为温度30℃、pH值7.0~9.0、NaCl浓度0.25 m/v、转速180 r/min。正交优化试验结果表明:菌粉吸附As^3+的最佳条件为菌粉投加量为0.02 g/L、吸附时间为2 h、pH值为8.0和温度为20℃,此条件下菌粉对As^3+的吸附量为128 mg/g。Langmuir方程与准一阶动力学方程可被较好的用于描述菌粉对As^3+的等温吸附特性与动力学特性,拟合度均达0.99,菌粉对As^3+的最大吸附量达114.6 mg/g。SEM-EDX与FTIR分析表明:吸附过程中的主要功能团-COOH、-OH、-NH、-CHO和O-P-O等与As络合,以及As^3+在菌粉表面与Mg2+发生了离子交换作用,促进了菌粉对As^3+的吸附。【结论】可为未来水体As污染微生物修复提供菌株材料与技术应用思路。

Biosorption characteristic and mechanism of As3+ from aqueous solution by a high arsenic-resistant strain of Microbacterium

【Objective】To evaluate the feasibility of removing As^3+ from aqueous solution,and to provide necessary remediation materials and theoretical basis for microbial remediation of As contamination.【Method】A strain of high arsenic-tolerant strain was obtained from a mining area in Hunan province.It was identified as Microbacterium by 16S rRNA sequence analysis and named A4.Univariate and orthogonal experiments were used to optimize the growing condition and As^3+adsorption condition of strain A4,respectively.Adsorption kinetics and isothermal experiments were conducted to study the adsorption characteristics of As^3+ by strain A4,and SEM-EDX and FTIR analysis were carried out to investigate the adsorption mechanism of As^3+ on the bacterial powder obtained from the strain A4.【Result】The minimum inhibitory concentration of the solid medium of strain A4 was 53 mmol/L.The optimum growth conditions for strain A4 were 30℃ of temperature,7.0-9.0 of pH value,0.25 m/v of NaCl concentration and 180 r/min of rotating speed.The optimal biosorption conditions of bacterial powder were:dosage of 0.02 g/L,contact time of 2 h,pH of 8.0 and 20℃ of temperature,the biosorption capacity reached 128 mg/g.Langmuir isotherm and pseudo first-order kinetic model whose R2 values both are 0.99 can be well used to describe the adsorption characteristics of the bacterial powders.The maximum adsorption capacity of As^3+was 114.6 mg/g.SEM-EDX and FTIR analysis showed that the main functional groups of the powder such as-COOH,-OH,-NH,-CHO and O-P-O were complexed with As,and As^3+ was ion exchanged with Mg^2+ on the surface of the powder,which promoted adsorption of As^3+by bacteria powder.【Conclusion】This study can provide available strain materials and technical application ideas for the further remediation of As in the water environment.