绿色木霉和草酸青霉对Hg^(2+)、Zn^(2+)、Cu^(2+)和Pb^(2+)的耐性和吸附特征

Tolerance and Biosorption Characteristics of Penicillium oxalicum and Trichoderma viride to Mercury,Zinc,Copper and Lead

【目的】通过对已筛选出的耐较高浓度重金属的绿色木霉和草酸青霉菌株进行Hg^(2+)、Zn^(2+)、Cu^(2+)和Pb^(2+)耐受性和吸附性试验,为其应用于土壤修复提供科学参考。【方法】通过测定重金属离子对菌株的生长抑制率和半致死浓度(EC_(50))评价真菌重金属耐性;将一定质量的菌丝球添加到已知浓度的重金属离子溶液中,测试菌株对重金属的吸附速率和吸附量,并对吸附过程进行函数拟合,分析其重金属吸附特征。【结果】2株菌株生物量随重金属浓度增加而降低,其过程分2个阶段,在金属离子浓度较低(0~200 mg·L^(-1))时,生物量下降不明显或略有上升,当重金属离子浓度大于某个临界值(400 mg·L^(-1)左右)时,生物量下降迅速;Hg^(2+)、Zn^(2+)、Cu^(2+)和Pb^(2+)对菌株lys2015f1的EC_(50)值分别是158.07、464.02、229.33和209.59 mg·L^(-1),对菌株lys2015f5的EC_(50)值分别是580.47、572.88、231.85、2 284.01 mg·L^(-1),因此,菌株lys2015f1对重金属耐受程度为Zn^(2+)>Cu^(2+)>Pb^(2+)>Hg^(2+),菌株lys2015f5对重金属耐受程度为Pb^(2+)>Hg^(2+)>Zn^(2+)>Cu^(2+)。菌株的吸附过程更加拟合准二级吸附动力学模型,由模型速率常数k_2可知,2株菌株吸附重金属速率排序变化一致,均为Pb^(2+)>Hg^(2+)>Cu^(2+)>Zn^(2+),菌株lys2015f1通过模型得到的理论Hg^(2+)、Zn^(2+)、Cu^(2+)和Pb^(2+)最大吸附量分别是37.12、14.63、16.62和107.31 mg·g^(-1),菌株lys2015f5理论最大吸附量47.12、16.50、25.78和201.22 mg·g^(-1);吸附的限速步骤是由化学反应控制的,在同等条件下,2株菌株对4种重金属吸附速率排序均为Hg^(2+)>Cu^(2+)>Zn^(2+)>Pb^(2+)。【结论】绿色木霉和草酸青霉菌株具有较高的重金属耐性和较好的吸附性,现有研究也表明其在生物防治、植物促生、土壤有机物降解等方面具有较好效果,因此2株菌株具有较好的重金属修复应用潜力。

[Objective]The study aims to research biosorption and tolerance of Hg2 ＋ ,Zn2 ＋ ,Cu2 ＋ ,Pb2 ＋ by Penicillium oxalicum and Trichoderma viride,and hopes to provide a scientific reference for its soil remediation. [Method]The heavy metal- tolerance of fungi was evaluated by measuring the growth inhibition rate of the two fungal varieties and the medial lethal concentration （EC50 ） of heavy metal ions. Firstly,a certain amount of mycelium balls were put into the heavy metal ion solution of known concentration. A few of hours later,the ion concentration was analyzed,and then the heavy metal adsorption efficiency and adsorption quantity were calculated,and the adsorption process was fitted with a function model.[Result]The results showed that biomass of the two strains decreased with increasing concentration of heavy metals,and the process could be divided into two stages. When the metal ions concentration was under 200 mg·L - 1 ,the biomass did not obviously decline or slightly increased. When the concentration was higher than critical value （ about 400 mg·L - 1 ）, the biomass dropped rapidly. The EC50 value of strain lys2015f1 in Hg2 ＋ ,Zn2 ＋ ,Cu2 ＋ ,and Pb2 ＋ solution was 158. 07,＆nbsp;464. 02,229. 33,and 209. 59 mg·L - 1 ,and it for strain lys2015f5 was 580. 47,572. 88,231. 85,and 2284. 01 mg· L - 1 . Thus,the tolerance degree of strain lys2015f1 to heavy metals was in the order of： Zn2 ＋ 〉 Cu2 ＋ 〉 Pb2 ＋ 〉 Hg2 ＋ ,and the tolerance level of strain lys2015f5 was Pb2 ＋ 〉 Hg2 ＋ 〉 Zn2 ＋ 〉 Cu2 ＋ . The adsorption process was more fitted to the pseudo-second-order kinetic model. According to the model rate constant k2 value,the adsorption rate of two strains was obtained,and the two strains had the same order in adsorption rate for those metal ions of Pb2 ＋ 〉 Hg2 ＋ 〉 Cu2 ＋ 〉 Zn2 ＋ . The theoretical value of the maximum adsorptions to （Hg2 ＋ ,Zn2 ＋ ,Cu2 ＋ ,Pb2 ＋ ） from this model for lys2015f1 was 37. 12,14. 63,16. 62,and 107. 31 mg·g - 1 ,and for lys2015f5 was 47. 12,16. 50,25. 78,and 201. 22 mg·g - 1 . The rate limiting step of adsorption was controlled by chemical reactions. In the same conditions,the order of two strains for heavy metal adsorption rate was Hg2 ＋ 〉 Cu2 ＋ 〉 Zn2 ＋ 〉 Pb2 ＋ .[Conclusion]The two strains have high heavy metal tolerance and adsorption. Combined with the functions of biological control,plant growth,degrading soil organic matter etc,the strains should have high potential abilities in remediation of heavy metals pollution.