在食品和环境监测中, 大肠杆菌是一个重要指标细菌, 因此, 对大肠杆菌的监测和灭菌效果也引起了人们广泛的关注。 基于荧光光谱检测技术具有的灵敏度高、 速度快、 稳定性强等优点, 利用荧光光谱技术研究了大肠杆菌的发射峰强度与大肠杆菌浓度的内在变化规律, 得到了一种更加方便、 快捷、 监测浓度更低的大肠杆菌计数方法。 采用289 nm的激发光照射大肠杆菌水溶液, 得到大肠杆菌的荧光发射光谱; 改变大肠杆菌溶液的浓度, 得到不同浓度大肠杆菌溶液的荧光光谱, 并分析大肠杆菌特征峰强度与大肠杆菌浓度的关系。 在此基础上, 利用荧光光谱技术研究了银纳米颗粒对大肠杆菌荧光发射的影响, 分析了银纳米颗粒对大肠杆菌的灭菌效果, 结果表明: (1)当289 nm的激发光照射大肠杆菌水溶液时, 大肠杆菌分别在332和425 nm两处有明显的荧光特征峰; 荧光特征峰强度随着大肠杆菌浓度降低而降低; 当大肠杆菌浓度小于20%时, 332和425 nm处特征峰强度与大肠杆菌溶液的浓度均呈线性关系。 (2)当大肠杆菌水溶液中加入银纳米颗粒时, 在4个小时内, 银纳米颗粒的作用时间越长, 大肠杆菌的荧光特征峰越弱, 即灭菌率越高; 增加银纳米颗粒的浓度或者提高环境温度, 均可提高银纳米颗粒对大肠杆菌的灭菌率。 本文的研究结果对食品、 环境等中大肠杆菌的计数和灭菌研究有参考意义。

Escherichia coli (E. coli) is an important indicator bacteria in food and environmental monitoring, therefore, monitoring the number and sterilization effect of E. coli has attracted extensive attention. Based on many advantages of fluorescence spectroscopy, such as high sensitivity, high speed, strong stability and so on, the relationship between the concentration of E. coli and the intensity of E. coli emission peak is studied, and a method for monitoring the concentration of E. coli conveniently, and rapidly at low concentration is given. Namely, the emission spectrum of E. coli can be got by irradiating E. coli solution with 289 nm excitation light, then the fluorescence emission characteristics of E. coli solution with different concentrations are given, and the relationship between the intensity of characteristic peak of E. coli and the concentration of E. coli is analyzed. Besides, the effect of silver nanoparticles on the fluorescence emission of E. coli is studied by fluorescence spectroscopy, and the sterilization effect of silver nanoparticles on E. coli is analyzed. The results show that: (1) E. coli has obvious fluorescence characteristic peaks at 332 and 425 nm respectively, when the excitation light at 289nm irradiates the aqueous solution of E. coli. The intensity of fluorescence peak decreases with the decreasing of E. coli concentration. And when the concentration of E. coli is less than 20%, there is a linear relationship between the concentration of E. coli and the intensity of characteristic peak at 332 and 425 nm. (2) When silver nanoparticles are added to the solution of E. coli, within 4 hours, the longer the existence time of silver nanoparticles is, the weaker the fluorescence characteristic peak of E. coli is, which means that sterilizing rate increases with the increasing of the time. Increasing the amount of silver nanoparticles or increasing the ambient temperature, the sterilizing rate of E. coli can be improved. The results of this paper are useful for the enumeration and sterilization study of E. coli in food and environment.