Effects of the initial concentration of microorganisms on inactivation by ultrasonic cavitation

Abstract

Abstract Ultrasonic sterilization is gaining progressively more attention for microbial sterilization without the drawbacks of heat, UV radiation, and chemical treatments. It is crucial to understand ultrasonic cavitation in heterogeneous media in order to disable microorganisms efficiently by ultrasound. In this study, the effect of initial bacterial concentration on the inactivation of Escherichia coli by ultrasonic cavitation was investigated over a wide range of frequencies. We found that the inactivation of microorganisms by ultrasound was frequency dependent, and the frequency dependence of the inactivation rate varied with the concentration. The results indicated that the strength of ultrasonic cavitation can vary with frequency and suggested that the mechanism of inactivation by ultrasound may vary with concentration.