Abstract:

As an emerging nonthermal disinfection technique , ultrasonic treatment is still in its infancy of industrial application due to the insufficient investigations into its inf1uencing rules on disinfection and its effects on cells. In order to solve this prohlem , Saccharomyces cerevisiae was chosen as the ohject to reveal the effects of three ultrasonic parameters on the inactivation of yeast cells. The parameters included the ulrasonic power , the irradiation time and the pulse ratio. Moreover , the selective medium method and the TEM were adopted to investigate the cell sublethal injmγcaused hy ultrasonic treatment and the cell ultramicrostructure after the treatment , respectively. The results show that (1) hoth the ultrasonic power and the irradiation time have significant positive effects on the inactivation of cells j (2) no s山letl叫injured cells are detected after the ultrasonic treatment j and (3) ultrasonic irradiation may result in great damage to cell ultramicrostructure. It is thus concluded that the damage of structural integrity could he the direct reason for the death of cells.

Key words: ultrasonic, disinfection, inactivation, yeast, cell