出芽短梗霉菌JB16铅镉吸附特性的研究

Adsorption properties of lead and cadmium by Aureobasidium pullulans JB16

摘要:

【目的】本文对污染土壤中的耐重金属菌株进行分离鉴定，研究菌株在不同条件下对吸附铅镉的影响因素。【方法】通过生理生化特征及ITS序列分析确定菌株种属，采用平板划线法确定最大耐铅镉浓度并探究菌株吸附的最佳条件；通过准二级动力学、Langmuir和Freundlich等温吸附的模型及红外光谱探究吸附过程。【结果】菌落形态和ITS序列分析鉴定表明，筛选分离的JB16为出芽短梗霉菌(Aureobasidium pullulans)，最大耐铅浓度达1500mg/L，最大耐镉浓度达750mg/L，最大耐铅镉混合浓度达1500mg/L和300mg/L。通过单因素实验(温度、时间、菌龄、pH、湿菌体浓度和初始重金属浓度)得出结论，在温度30℃、时间2h、菌龄72h、pH 6、湿菌体浓度5g/L和初始铅浓度150mg/L的最佳条件下，菌体对铅的吸附率为88.5%；在温度30℃、时间1h、菌龄96h、pH 6、湿菌体浓度5g/L和初始镉浓度20mg/L的最佳条件下，菌体对镉的吸附率为59.4%。菌株吸附铅镉过程符合Langmuir吸附模型和准二级动力学模型，为表面单分子层吸附。扫描电镜和红外光谱分析表明，重金属离子对菌体造成影响，吸附前后形态发生变化，细胞表面的羟基、羧基、饱和C−H键和酰胺基等基团参与了吸附过程。【结论】菌株JB16具有一定的铅镉吸附效果，为修复重金属铅镉污染的水体和土壤提供宝贵的菌种资源和数据支持。

Abstract:

[Objective] To isolate and identify a heavy metal-resistant strain in the polluted soil and explore the factors influencing the adsorption of the strain for lead and cadmium under different conditions. [Methods] The strain was identified based on physiological and biochemical characteristics and ITS sequence. The streak plate method was employed to determine the maximum lead and cadmium tolerance of the strain and to explore the optimal conditions for the adsorption of lead and cadmium. The adsorption process was studied by pseudo-second-order kinetics, Langmuir and Freundlich models, and infrared spectroscopy. [Results] Strain JB16 was isolated and identified as Aureobasidium pullulans, which can tolerate the maximum lead concentration of 1 500 mg/L, the maximum cadmium concentration of 750 mg/L, and the maximum lead-cadmium mixture concentration of 1 500 mg/L and 300 mg/L, respectively. The single factor experiments (temperature, time, cell age, pH, wet mycelial concentration, and initial heavy metal concentration) optimized the lead adsorption conditions as follows: 30 ℃, 2 h, cell age of 72 h, pH 6, wet mycelial concentration of 5 g/L, and initial lead concentration of 150 mg/L, under which the adsorption rate of lead was 88.5%. The optimum conditions for cadmium adsorption: 30 ℃, 1 h, cell age of 96 h, pH 6, wet mycelial concentration of 5 g/L, and initial cadmium concentration of 20 mg/L, under which the adsorption rate of cadmium was 59.4%. The adsorption process of lead and cadmium by the strain conformed to the Langmuir model and the pseudo-second-order kinetic model, which indicated surface monolayer adsorption. The results of scanning electron microscopy and infrared spectroscopy demonstrated that the heavy metal ions changed the morphology of the strain, and the hydroxyl, carboxyl, saturated C-H bonds, and amide groups on the cell surface participated in the adsorption. [Conclusion] Strain JB16 can adsorb lead and cadmium, which enriches the strain resources and provides data support for the remediation of water and soil contaminated by lead and cadmium.