脉冲强光对大肠杆菌的灭活效果及其动力学模型的建立

为研究脉冲强光对大肠杆菌的杀菌效应,试验以大肠杆菌ATCC 8739为对象,研究了不同生长期、pH和温度对脉冲强光杀菌效果的影响,并对其杀菌动力学进行Linear和Weibull模型拟合。结果表明:培养了6 h的对数期大肠杆菌对脉冲强光处理最为敏感,处理1 s能够降低(2.31±0.16)lg cfu/mL。pH和温度对脉冲强光杀菌效果有很大影响,介质温度在35~45 ℃,pH4.0~6.0或pH8.0都能促进脉冲强光的灭活作用。不同脉冲距离和时间下,Linear和Weibull模型都能够很好地拟合脉冲强光对大肠杆菌的杀菌效果(R²>0.99),且Weibull模型更为精确,但杀菌效果最终取决于辐射通量(可通过调节脉冲距离和脉冲时间改变)。总之,脉冲强光技术可以作为一种有效杀灭大肠杆菌的非热杀菌技术,其杀菌过程符合Linear和Weibull模型,且Weibull更为精确,该模型可以为饮用水消毒提供参考。

Inactivation Effect of Pulsed Light on Escherichia coli and the Establishment of Its Kinetic Model

In order to investigate the impact of pulsed light (PL) on Escherichia coli (E. coli), E. coli ATCC 8739 was used as the object. The effects of different growth phases, pH and temperature on sterilization effect were studied. Besides, Linear model and Weibull model was assessed to describe the pulsed light inactivation model. The results showed that E. coli cultured for 6 h at logarithmic phase was most sensitive to PL, which reduced (2.31±0.16) lg cfu/mL of E. coli after treatment for 1 s. pH and temperature also affected the inactivation evidently. High temperature (35~45)℃, acidic (pH4.0~6.0) or alkaline (pH8.0) conditions could promote the inactivation effect of PL. In addition, both Linear and Weibull model provided a good fit to the inactivation curves of E. coli (R2>0.99) under variation of pulse distance and time. Compared with Linear model, Weibull model was more accurate. But the inactivation caused by PL depended on the way of fluence dosage in reality, which could be regulated by time or the distance. In conclusion, as a sterilization technology, PL was an effective way to inactivate the E. coli and the bactericidal curves of E. coli was fitted well by Linear and Weibull model. Furthermore, Weibull model fitted the dynamics process of PL sterilization better, which could provide theoretical basis for the application of PL in drinking water sterilization.