2株耐镉微生物的筛选及其对镉的吸附钝化差异机制  

Screening of two cadmium tolerant microorganisms and their differences in adsorption and immobilization of cadmium

作　　者：张旭辉[1] 孙斌 魏志敏 赵晨雨 徐源洲 张力浩 徐莉[1] ZHANG Xuhui;SUN Bin;WEI Zhimin;ZHAO Chenyu;XU Yuanzhou;ZHANG Lihao;XU Li(College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China)

机构地区：[1]南京农业大学资源与环境科学学院

出　　处：《南京农业大学学报》2019年第5期869-876,共8页Journal of Nanjing Agricultural University

基　　金：国家重点研发计划项目(2017YFD0800305);江苏省优势学科平台资助项目

摘　　要：[目的]从镉污染土壤中筛选2株耐镉微生物,并对其吸附钝化特征进行初步探究。[方法]选用系列梯度含镉固体培养基,进行耐镉微生物的筛选,并通过16SrRNA基因序列比对进行初步鉴定。将2株耐镉菌在含50mg·L^-1镉离子的LB液体培养基中培养,通过实时监测菌液D600值、pH值及胞外聚合物的变化,明确其在镉胁迫下对镉的吸附钝化差异机制。[结果]筛选获得2株具有较强耐镉能力的菌株(ZXH21和ZXH23),在镉质量浓度为600mg·L^-1的固体LB培养基上生长良好。经16SrRNA鉴定,分别为无色杆菌属(Achromobacter sp.ZXH21)和假单胞菌属(Pseudomonas sp.ZXH23)。2株菌在镉质量浓度为50mg·L^-1的液体培养基培养过程中,对镉离子均有一定的吸附钝化能力,2株菌对镉的去除效果相近,菌株ZXH21和菌株ZXH23对镉的最大去除率分别为36.5%和33.7%。2株菌对镉的去除机制均以胞外吸附为主,吸收为辅,但吸附率和吸收率不同。在72h时,菌株ZXH21的吸附率和吸收率分别为25.3%和0.6%,菌株ZXH23的吸附率和吸收率分别为30.6%和0.1%,菌株ZXH21吸收率为菌株ZXH23的6倍。[结论]菌株ZXH21比菌株ZXH23有更强的耐镉生长能力及稳定的去除潜力,菌株ZXH21去除镉的主要机制是生物量的增加以及分泌可溶性多糖。菌株ZXH23去除镉的主要机制可能是表面吸附以及分泌不可溶性蛋白和不可溶性多糖。[Objectives] Two cadmium-tolerant microorganisms were isolated,and their adsorption and immobilization characteristics of cadmium were explored preliminarily.[Methods] In this study,cadmium-tolerant microorganisms were isolated with a series of cadmium-containing solid media,and 16S rRNA gene sequencing was performed to identify the bacteria.Two strains were cultured in LB liquid culture with 50 mg · L^-1 cadmium,and D 600 value,pH value,and extracellular polymerization were monitored during the incubation.The different mechanisms of cadmium adsorption and immobilization were studied.[Results] Two strains with strong cadmium tolerance were isolated,and grew well under 600 mg · L^-1 cadmium in LB plate.They were identified as Achromobacter sp.(ZXH21)and Pseudomonas sp.(ZXH23)by 16S rRNA gene sequencing.Both strains had certain cadmium adsorption and immobilization ability under 50 mg · L^-1 cadmium treatment,and the cadmium removal efficiency was similar.The maximum removal of cadmium by ZXH21 and ZXH23 were 36.5% and 33.7% respectively.The removal mechanism of cadmium by both strains was mainly extracellular adsorption,with absorption as a supplement,however,the rate varied.At 72 h,the adsorption and absorption rates of ZXH21 were 25.3% and 0.6% respectively,and those of ZXH23 were 30.6% and 0.1%.The absorptivity of the two strains were quite different,and ZXH21 was 6 times higher than that of ZXH23.[Conclusions] ZXH21 had stronger cadmium tolerance and more stable removal potential than ZXH23.The main mechanism of cadmium removal by ZXH21 was by the biomass increment and the secretion of soluble polysaccharides.Surface adsorption,secretion of insoluble proteins and insoluble polysaccharides might be the main factors for the cadmium removal of ZXH23.

关 键 词：耐镉 吸附 无色杆菌属 假单胞菌属 去除率 

分 类 号：X172[环境科学与工程—环境科学] X53