Studies On Kinetics Of Batch Ethanol Fermentation And Fed-batch Ethanol Fermentation By Saccharomyces Cerevisiae GGSF16

The process of microorganism fermentation had the characteristic of dynamicchanging and nonlinearity. In order to improve ethanol concentration, the study on thesugar utilization, ethanol formation and biomass growth during the ethanolfermentation was necessary. The batch fermentation process of ethanol and thefermentation kinetics by Saccharomyces cerevisiae GGSF16were studied. On thisbasis, fed-batch fermentation to achieve a high-level of ethanol production wasinvestigated. Result is reported as following:(1)The growth characteristics of Saccharomyces cerevisiae GGSF16underdifferent conditions were studied. We observed that the slower growth rate wasachieved by the lower initial pH value and the highest sugar and ethanol concentration.The growth rate was inhibited since the pH value<4.0, exogenous ethanolconcentration>6%(v/v), initial sugar concentration>200g/L. In addition,Saccharomyces cerevisiae GGSF16was not grow when exogenous ethanolconcentration greater than9%(v/v).The optimum temperature for yeast growing was32?.(2)In order to study on the effect of initial glucose concentration on ethanolfermentation by Saccharomyces cerevisiae GGSF16? the Logistic model has beenproposed to simulate the progression of batch fermentation with different initialglucose concentration. As the result show that the high initial glucose concentration(>211g/L) has significant inhibition in the rate of ethanol fermentation. The optimalinitial glucose concentration is286.5g/L?the ethanol concentration?glucose utilizationand fermentation efficiency at final time was133.14g/L,99.07%,90.95%, respectively.On this basis, kinetics of ethanol fermentation by Saccharomyces cerevisiae GGSF16was investigated. In order to study on the sugar utilization, ethanol formation andbiomass growth during the ethanol fermentation, particle swarm optimization wasused to estimate parameters from seven different kinetics models. Each model hasbeen proposed to simulate the progression of batch fermentation with initial glucoseconcentration of286.5g/L. The results showed that phisalaphong's model can beaccorded with high-level ethanol fermentation process with initial glucoseconcentration of246,286.5,321g/L, respectively.(3)To improve the ethanol yield?fed-batch fermentation was investigated. Duringthe study by using flask?an fed-batch strategy was eventually established. The totalsugar concentration, initial sugar concentration, feeding sugar concentration andfeeding time were320g/L,210g/L,650g/L,18h,respectively.The ethanol concentration?and fermentation efficiency at final time is147.94g/L and90.47%.It was increased by10.28%and10.30%comparing with batch fermentation. (4)The fed-batch ethanol fermentation with aeration rate of0.08L/min bySaccharomyces cerevisiae GGFS16in a5L bioreactor was studied. The resultsshowed that the ethanol concentration?glucose utilization and fermentation efficiencyat final time was150.31g/L?91.92%and99.97%, respectively. Finally, liquefiedcassava mash filtrate was instead of YEPD culture into fed-batch fermentation underthe same condition. The results showed that the ethanol concentration? glucoseutilization and fermentation efficiency at final time was146.75g/L,89.74%and93.28%.