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.