Analysis Of The Regulation Of Organic Acid Metabolism In S.cerevisiae Grown Under Different Culture Conditions

S.cerevisiae not only plays an important role in industrial application, but also becomes avery nice model organism for research in many areas. Nevertheless, the in vivo response tovarious culture conditions and the systematical regulation mechanism of metabolism hereby isstill not clearly known. The research on which has always been a focus issue in theoretical orapplied study. The present study combine the approach of fermentation characteristics,enzyme assay and metabolic flux analysis to investigate the regulation of central carbonmetabolism of S.cerevisiae under different culture conditions.In this study we use the glucose, fructose and maltose as carbon source for culture S.cerevisiae, measured metabolic pathway in the middle of some representative of the enzymeactivity in different culture conditions,including the means of glycolysis (PK, PYK), Pentosephosphate way (glucose-6-phosphate dehydrogenase, G6PDH), TCA(ICDH, ICDH; MDH,MDH), alcohol dehydrogenase (YADH). We do the preliminary analysis about the responseof the major enzyme activity which adapt to differerent intracellular metabolic system,thisanalysis provides some basic information to metabolic flux analysis, and we intgeration thegrowth-related parameters in the fermentation process, based on the response Dynamic modelμ=μ (t), the main research is about S. cerevisiae which grows with the glucose, fructose andmaltose as carbon source under the circumstances to suit different situations arising inresponse to intracellular metabolism.The physiological metabolism of Saccharomyces cerevisiae under high osmotic stresswas studied. Glycerol and trehalose are the primary compatible solutes in S. cerevisiae. Underhigh osmotic stress, the ethanol concentration, the glycerol concentration and the trehalosecontent respectively increased by100%,400%and11%compared with that of the controlones. The metabolic flux analysis indicated that the carbon flux for trehalose synthesis atglucose-6-phosphate node increased by47.3%under osmotic condition. At the same time, thecarbon flux for glycerol synthesis at dihydroxyacetone phosphate (DHAP) andglyceraldehyde-3-phosphate (GAP) node increased by55.7%. The carbon flux for ethanol synthesis at pyruvate node increased by300%, while the carbon flux flowed toward TCAcycle decreased by21.7%.The enzyme activity differences was analysed among different generations beer yeast onpyruvate kinase, glucose-6-phosphate dehydrogenase, malate dehydrogenase, isocitratedehydrogenase, and ethanol dehydrogenase, the result showed that the change of metabolickey enzymes activities during successive subculture, and the pyruvate kinase,glucose-6-phosphate dehydrogenase and ethanol dehydrogenase had obvious changes, thatwas also closely related to yeast viability, yeast viability was vigorous and metabolism yieldwas Harmonious when the three enzyme activity was high.