Critical damage to the cellular organelles of Saccharomyces cerevisiae under sublethal conditions upon high pressure carbon dioxide treatment

High pressure carbon dioxide treatment is a non-thermal pasteurization technique. However, critical damage, resulting from the treatment, to microbial cells has not been observed directly, and the detailed mechanism of the microbicidal activity is not understood. In this study, we analyzed the damage to Saccharomyces cerevisiae organelles, which were visualized using organelle-specific GFP fusion proteins. Yeast strains were subjected to high pressure carbon dioxide treatments at 30 degrees C and 4.0MPa for 2-8h. Reduction in yeast cell viability was accompanied by the disruption of endoplasmic reticulum, nuclear membrane, Golgi body, and nucleolus. However, visible damage to the cell membrane was not observed. Fluorescence microscopy was utilized to confirm that high pressure carbon dioxide treatment damaged membranes of major organelles, but not the cell membrane.