镧和铈对蜡状芽孢杆菌抗性、生长及胞内核酸的影响

Effect on resistance, growth and DNA of Bacillus cereus treated by La3+ and Ce3+

摘要:

【目的】研究稀土元素对细菌生理效应的影响及机理。【方法】用抑菌圈法和光电比浊法测定了硝酸镧和硝酸铈对蜡状芽孢杆菌抗性及生长的影响, 并用傅立叶变换红外光谱和荧光分光光度法研究了细菌细胞壁及胞内DNA的结构。【结果】40?50 mg/L硝酸镧增强了细菌对9%石炭酸, 0.135%升汞, 8×105 U/mL青霉素的抗性; 40?50 mg/L硝酸铈增强了细菌对9%石炭酸, 0.135%升汞, 8×105 U/mL青霉素和75%次氯酸钠的抗性; 稀土元素会加快蜡状芽孢杆菌生长和繁殖速度, 同时高浓度稀土元素的促进作用要比低浓度时更明显, 表明稀土元素可以刺激细菌繁殖; 红外光谱表明稀土元素会影响细菌细胞壁肽聚糖结构, 荧光分光光度法结果显示稀土元素会影响细菌胞内DNA的结构。【结论】细菌抗性的改变可能与细胞壁肽聚糖结构受到影响有关; 稀土元素对DNA的影响可能是抗性和生长受到影响的根本原因。

Abstract:

[Objective] The physiological effect of rare earth element (REE) on microorganism resistance, growth and its mechanism were studied in this work. [Methods] The effects of REE on resistance and growth of Bacillus cereus were investigated through inhibition zone method and photoelectric turbidimetry method, respectively, fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy were used to examine the change in structure of cell wall and nucleic acid (DNA). [Results] Resistance of bacteria to 9% Carbolic acid, 0.135% HgCl2 and 8×105 U/mL Penicillin enhanced by 40?50 mg/L La(NO3)3, meanwhile, resistance to 9% Carbolic acid, 0.135% HgCl2, 8×105 U/mL Penicillin and 75% NaClO3 enhanced by 40?50 mg/L Ce(NO3)3. Fission of bacteria could be faster due to tremeant of REE, effect of more La(NO3)3 or Ce(NO3)3 was better than less them. The structure changes of peptidoglycan characterized by FTIR indicated the effect of La(NO3)3 and Ce(NO3)3 on cell wall. Therefore, modification of resistance was considered related to it. The structure of DNA coubld be affected by REE througth fluorescence spectroscopy. [Conclusion] The change of DNA structure was the basic cause that effect on resistance and growth of REE.