Viability of yeast cells in propagating ultrasonic waves

Abstract

In some recent papers the upper limits for the acoustic pressure amplitudes, in standing wave fields, that exert no measurable influence on viability of various biological cells have been reported. However, the pressure amplitude in a standing wave is periodically varying in space in the direction of sound propagation and, because of radiation pressure, the cells are not homogeneously distributed within the sample volume, resulting in effects arising from the dynamic environments created. Thus standing waves are obviously not appropriate to study the direct influence of sound pressure amplitude on viability data. Therefore, both metabolic activity/viability of yeast cells and their ability to replicate as a function of acoustic frequency and sound pressure amplitude have been investigated in propagating waves. The observed effects are compared to those in crossed beam fields and in standing plane wave fields. The results allow a better forecast and interpretation of viability threshold data relevant in predicting the effects of acoustic parameters in standing wave fields. [Work supported in part by the European Commission, Contract No. ERBFMRXCT970156.]