一株耐铅镉真菌的分离鉴定及其吸附特性的研究

Isolation, identification and biosorption characteristics of a lead and cadmium resistant fungus

摘要:

[目的] 以扎龙湿地污染的土壤为材料，进行耐铅镉菌株的分离鉴定，研究不同条件对菌株吸附铅镉的影响。[方法] 采用平板划线法，逐级驯化，筛选出一株耐铅镉菌株，通过生理生化特征及ITS序列分析对菌株进行鉴定，探究该菌吸附的最佳条件，并进行Langmuir和Freundlich等温吸附模型拟合。[结果] 本研究分离得到一株菌株JB15，最高耐受浓度为Pb²⁺ 1200 mg/L、Cd²⁺ 200 mg/L，经鉴定为球孢白僵菌，最佳吸附条件温度为30，pH为7.0，接菌量为8.0 g/L，吸附时间为60 min，铅镉吸附率分别为52.27%和62.38%；铅镉吸附量分别为19.60 mg/g和3.98 mg/g，符合Langmuir等温吸附模型。[结论] 菌株JB15具有较好的吸附效果，可为微生物修复重金属土壤污染提供理论基础。

关键词:铅镉;分离鉴定;球孢白僵菌;生理生化;生物吸附

Abstract:

[Objective] A lead and cadmium resistant strain was isolated from the polluted soil of Zhalong wetland, and the influences on lead and cadmium adsorption under different conditions are discussed. [Methods] The streak plate method and progressive domestication were used for screening lead and cadmium resistant strain. The strain was identified by physiological and biochemical tests, and by ITS sequence analysis. The optimal condition of the lead and cadmium resistant strain was explored, and Langmuir and Freundlich isothermal adsorption models were used. [Results] A lead and cadmium resistant strain JB15 was isolated as Beauveria bassiana, and the maximum tolerant Pb²⁺ and Cd²⁺ concentration of the strain was 1200 mg/L and 200 mg/L, respectively. Optimum conditions for adsorption were found at pH of 7.0 with inoculation quantity of 8.0 g/L, at 30℃ for 60 min. Under such conditions, the lead and cadmium adsorption rate reached 52.27% and 62.38%, and the lead and cadmium adsorption capacity reached 19.60 mg/g and 3.98 mg/g, respectively. The adsorption process of the strain was fitted well on Langmuir adsorption isotherm model. [Conclusion] The isolated strain JB15 has a good adsorption effect and provides theoretical foundation for microbial remediation of soil heavy metal contamination.

Key words:lead and cadmium;isolation and identification;Beauveria bassiana;physiological and biochemical;bioadsorption