Ultrasonic disruption of yeast cells: Underlying mechanism and effects of processing parameters

Abstract

During the ultrasonic treatment of yeast cells, the damage to the cell walls and membranes was monitored by assessing the release of cell wall polysaccharides and intracellular proteins, respectively. At a low acoustic intensity (10 W/cm2), the polysaccharides were released faster than the proteins, whereas at higher acoustic intensities (24 and 39 W/cm2), this trend was reversed. At elevated temperatures, additional cell wall polysaccharides were released, whereas fewer intracellular proteins were released. Increasing processed volumes, initial cell concentrations, and salt concentrations led to the decrease of both fractions. However, the total releases per ultrasound treatment remained constant regardless of the processed volumes, and increased with the increase of initial cell concentrations. The results suggest that the ultrasonic disruption of yeast cells begins with the breakdown of the cell wall before continuing to the cell membrane. These findings may offer new avenues for exploring more efficient cell disruption or microbial inactivation processes. Ultrasonic technology has been intensively studied for microbial inactivation or cell disruption. It is believed that the inner cell membrane is the target of the ultrasonic damage. The mechanism of microbial inactivation via ultrasound involves the thinning of the cell membranes. In this study, we monitored the ultrasonic damage to yeast cell walls and membranes by monitoring the release of cell wall polysaccharides and intracellular proteins, respectively. Our results demonstrate that the ultrasonic disruption of yeast cells begins with the breakdown of the cell wall before continuing to the cell membrane. Increasing the temperature weakens the cell wall and thermally coagulates the intracellular proteins. Increasing the processed volumes, initial cell concentrations, and salt concentrations reduces the releases of cell wall polysaccharides and intracellular proteins from the viewpoint of yeast cells. However, the total releases of each fraction per ultrasound treatment remain constant regardless of the processed volumes, and increase with increasing initial cell concentrations. Our results may offer new insights towards the exploration of more efficient industrial processes for microbial inactivation or cell disruption, and in elucidating the effects of processing parameters.