Scanning electron microcopy (SEM) and differential scan calorimetry (DSC) were used to evaluate structure changes in Saccharomyces cerevisiae cells under the treatment of high-pressure CO2 over the fermentation broth. Compared with controlled fermentation

the ethanol concentration in the fermentation broth after 24 h greatly decreased under high-pressure CO2. DSC studies of whole cells showed that the ribosomes and DNA were not changed after high pressure CO2 treatment although some components were denatured

leading to the lowering of the corresponding decomposition temperature. The fermentation under 1 and 8 MPa CO2 caused obvious changes on the wall surface of cells.Wrinkles were formed on the wall of cells and the cell wall coarseness increased at elevated pressure as observed with SEM observations.