Mechanistic studies on the inactivation of Saccharomyces cerevisiae by high pressure

Abstract

High hydrostatic pressure (HP) processing is a technology that can be applied as a food preservation process. Here, we show that mild HP treatments, a typical example being 15 min 300 MPa at 25°C, leads to a change in the cell wall protein structure of Saccharomyces cerevisiae such that cells are sensitised towards a treatment with β-1,3-glucanase. A deletion mutant with an impaired trehalose synthesis showed a 2 log increased inactivation compared to its parent strain when treated for 15 min with 200 MPa pressure at 25°C. It is well known that trehalose protects yeast membranes. However, plasma membrane-related propidium iodide uptake did not correlate quantitatively with the observed decrease in colony-forming units. We concluded that the primary HP inactivation step of yeast cells presumably involves a perturbation of (intracellular) membranes.