应用红外方法探讨耐镉菌株高积累Cd^(2+)的机理

Research on high accumulating Cd^(2+) mechanism of a toletant-Cd^(2+) strain by Infrared spectroscopy analysis

从安徽某冶炼厂污染土壤中分离出一株能耐高浓度镉的菌株(J5),经初步鉴定为假单胞菌属(Pseudomonassp.).该菌株在液体培养基中耐受40mmol.L-1CdSO4,在固体培养基上耐受75mmol.L-1CdSO4.培养基中Cd2+、Zn2+、Pb2+、Cu2+浓度分别为100mg.L-1和Mn2+浓度为275mg.L-1时,菌株生长正常.在重金属Cu2+、Pb2+、Zn2+、Mn2+存在时,采用红外光谱与原子吸收光谱分析菌株对Cd2+的积累,结果表明,在低浓度Cd2+溶液中菌株细胞对Cd2+的积累,主要靠细胞壁上—NH2与Cd2+配位结合;在高浓度Cd2+溶液中,细胞壁上—NH2、—OH、—COOH、—PO43-、—M—O(O—M—O)基团吸附Cd2+的能力显著.Mn2+可以增加细胞壁上有效官能团活性,提高Cd2+积累率;但当有Zn2+、Pb2+、Cu2+重金属离子共存时,即使有Mn2+存在,菌体对Cd2+吸附积累能力未见提高.

A tolerant-cadmium strain J5, isolated from the polluted soil around the smeltery in Anhui province, was identified as Pseudomonas sp. strain. It can tolerate 40 mmol·L^- 1 cadmium sulphate in liquid medium and 75 mmol· L^- 1 Cd^2＋ in solid medium. The strain grew normal in the presence of 100 mg·L^- 1 of Cd^2＋、Zn^2＋、Pb^2＋、Cu^2＋ and 275 mg·L^-1 of Mn^2＋ , respectively. The accumulation to Cd^2＋ in the strain was observed by infrared spectroscopy and atomic absorption spectroscopy, in the presence of Cd^2＋、Pb^2＋、Zn^2＋、Mn^2＋ . The results indicated that in low Cd^2＋ concentration, -NH2 group on the cell wall mostly match with Cd^2＋ . When in high Cd^2＋ concentration, -NH2, -OH, -COOH, -PO4^3- and -M-O（O-M-O）groups strongly adsorbed Cd^2＋ . Mn^2＋ increased the activity of the groups mentioned above, and facilitated the accumulation of Cd^2＋ on the cell wall. In contrast, Zn^2＋、Ph^2＋、Cu^2＋. ions coexisting decreased such adsorption and accumulation, even if in the Bresence of Mn^2 ＋ .