1株耐Cd细菌的分离、鉴定及其吸附特性研究

从长期受农药污染的土壤中分离筛选到1株可耐受重金属Cd的菌株,经形态观察、生理生化特性、16S rRNA基因序列和系统发育分析确定该菌株为路德维希肠杆菌(Enterobacter ludwigii),命名为EM1,为Cd污染水体及土壤的修复提供微生物菌株。在无机盐培养基中菌株EM1对Cd~(2+)的最适耐受质量浓度为50 mg/L,吸附Cd~(2+)的最适生长温度为35℃,最适pH值为6.0,在此条件下,其对Cd~(2+)的吸附率最大,为92%。电镜扫描结果表明,在吸附Cd~(2+)的过程中菌体表面分泌大量的胞外多聚物且菌体形态发生变化。红外光谱分析显示,Cd~(2+)胁迫条件下,菌体细胞壁结构并未发生变化,菌株吸附Cd~(2+)的过程主要与菌体表面的羟基、N-H、C-H、多糖中的C-O-C及酰胺基团有关。

Isolation,Identification and Adsorption Characteristics of a Cd-tolerant Bacterium

A Cd-tolerant strain was isolated from the pesticide polluted soil,on the basis of morphological observation,physiological and biochemical characteristics,16S rRNA gene sequence and phylogenetic analysis,the strain was identified as Enterobacter ludwigii,and named as EM1,so as to provide strain for remediation of Cd polluted water and soil.The optimal Cd2+ concentration of strain EM1 against Cd2+ was 50 mg/L,the optimum growth temperature of strain EM1 against Cd2+ was 35 ℃,and the optimum pH value of strain EM1 against Cd2+ was about 6.0.Under this condition,the Cd2+ adsorption rate of EM1 was the highest,reached 92％.The SEM results showed that in the process of adsorption of Cd2+,the morphology of the strains was changed,and a large number of extracellular polymeric substances were secreted on the strain surface.Infrared scanning analysis showed that under the Cd2+ stress condition,the cell walls structure had not changed,and hydroxy,N-H,C-H,C-O-C and aminoacyl were confirmed to be the key functional groups for the strain to adsorb Cd2+.