蜡状芽孢杆菌抗重金属性能及对镉的累积

所研究的蜡状芽孢杆菌RC可以在镉浓度为200mg·L-1的固体培养基平板上生长良好,表明菌株具有强抗镉的能力。该菌株在液体培养基中Cd2＋、Cr3＋、Pb2＋浓度均为75mg·L-1和Mn2＋浓度为100mg·L-1培养时,菌株生长正常。在重金属Cr3＋、Pb2＋、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,培养基中其他重金属离子的加入,会影响菌株对Cd2＋的积累率;当Cr3＋存在时,Cr3＋可以增加细胞壁上有效官能团活性,明显提高RC菌体对Cd2＋的积累率,而其他重金属组合对Cd2＋吸附积累能力影响不大;RC细胞壁上活性基团-OH、-NH-、-COOH、-PO34-和-M-O（O-M-O）活跃参与Cr3＋、Pb2＋、Mn2＋和Cd2＋多种重金属离子的络合作用。通过高温和十二烷基硫酸钠处理菌株进行质粒消除试验,未发现该菌株的抗镉性质与抗性质粒的存在相关。

Characterization of Heavy Metal Resistance and Cd-accumulation on a Bacillus cereus Strain

The Cd-resistant Bacillus cereus RC grows well on media plates containing 200 mg. L-1 cadmium. The strain grew normally in the presence of 75 mg.L-1 of Cd2＋, Cr3＋, Pb2＋ or 100 mg.L-1 of Mn2＋. The accumulation to Cd in the strain was observed by infrared spectroscopy and atomic absorption spectroscopy, in the presence of Cr3＋, Pb2＋ or Mn2＋. The results indicate that the presence of the other heavy metals affected the accumulation of Cd2＋. Cr3＋ increased the activity of the groups and facilitated the accumulation of Cd2＋ on the cell wall. Adsorption and accumulation varied only slightly in media containing the other metal ions. This shows that -OH, -NH, -CO, -CO-NH- and -PO4^3- groups on the cell wall of RC actively participate in the complexing of Cr＋, Pb2＋, Mn2＋ and Cd2＋ions. A plasmid elimination experiment suggests that Cd-resistant genes were not located on its plasmid. The results of this study show that this strain is resistant to cadmium and indicate the possible usefulness of this strain for bioremediation of sites contaminated with cadmium.