Use of supercritical carbon dioxide for proteins and alcohol dehydrogenase release from yeast Saccharomyces cerevisiae

Abstract

In this study, supercritical carbon dioxide (SC CO2) was used to obtain proteins and enzymes from yeast Saccharomyces cerevisiae.The changes in viability and cell morphology, the release of the cellular proteins and the activity alteration of the enzyme alcohol dehydrogenase (ADH) from S. cerevisiae resulting from the exposure to SC CO2 were investigated. Before the treatment of S. cerevisiae in SC CO2, the number of viable cells was cca. 105 colony forming units per mL of cell suspension (cfu/mL). The suspension of the S. cerevisiae culture was incubated in SC CO2 at different pressures (7.5, 15 and 30MPa) for different treatment times (30–300min) and at constant temperature (35°C). The influences of these parameters on total protein concentration, ADH activity and changes in absorbance of nucleic acids (NA) in the suspension of S. cerevisiae during SC CO2 treatment were studied. A decrease in number of living cells of S. cerevisiae in potato dextrose broth (PDB) or in sodium pyrophosphate buffer (SPB) exposed to SC CO2 at all studied pressures was determined when the treatment time was increased. The highest activity of ADH after treatment of the yeast culture suspended in PDB in SC CO2 was detected at a pressure of 7.5MPa and at the treatment time of 120min.The use of SC CO2 is a suitable option to achieve cell death and consequently the secretion of proteins and ADH from cells of S. cerevisiae.