Study On Process Of Ethanol Production From Sugarcane Juice With Different Concentration Of Total Initial Sugar By Saccharomyces Cerevisiae GJ2008

Sugarcane juice is main raw material for sucrose production. Process of ethanolfermentation from sugarcane juice with different concentration of total initial sugar wasinvestigated in this thesis in order to expand application of sugarcane juice and provide abasis for efficient ethanol production from sugarcane juice.Ethanol tolerance analysis showed that Saccharomyces cerevisiae GJ2008had15%（v/v）ethanol tolerance. The pH analysis showed that initial pH4.0was found to be an optimum forethanol fermentation in the shake flask. Shake flask fermentation indicated that strain GJ2008cultured in250g·L^-1total initial sugar gave12.87%（v/v） of ethanol content with78.54%fermentation efficiency.Changes of fermentation parameters during the ethanol fermentation from sugarcanejuice with different concentration of total initial sugar by Saccharomyces cerevisiae GJ2008under batch condition were studied. The results showed that strain GJ2008cultured insugarcane juice with total initial sugar at concentrations of153.65g·L^-1,175.51g·L^-1,200.80g·L^-1,222.53g·L^-1and248.04g·L^-1，respectively gave the maximum total sugar consumptionrates with the values of16.03g·L^-1·h-1,13.48g·L^-1·h-1,15.86g·L^-1·h-1,19.34g·L^-1·h-1and20.59g·L^-1·h-1，respectively and the maximum ethanol productivities with the values of8.70g·L^-1·h-1,7.50g·L^-1·h-1,8.60g·L^-1·h-1,6.40g·L^-1·h-1and7.90g·L^-1·h-1, respectively. Theresults also showed that the ethanol contents were9.1%（v/v）,9.9%（v/v）,11.7%（v/v）,12.1%（v/v）and12.9%（v/v）, respectively and the fermentation efficiencies were91.45%，87.09%，89.97%，83.96%and80.30%, respectively, when the strain GJ2008was cultured insugarcane juice with total initial sugar at concentrations of153.65g·L^-1,175.51g·L^-1,200.80g·L^-1,222.53g·L^-1and248.04g·L^-1，respectively.In order to improve fermentation efficiency of the strain GJ2008, ethanol fermentationfrom sugarcane juice with actual total sugar at a concentration of245.65g·L^-1was carried outin5L bioreactor under fed-batch condition. The fed-batch fermentation results indicated thefinal ethanol concentration, residual total sugar and fermentation efficiency were14.3%（v/v）,12.89g·L^-1and89.93%, respectively. The results also indicated that the fermentationefficiency （89.93%） of the strain GJ2008under fed-batch condition with actual total sugar at aconcentration of245.65g·L^-1was higher than that （80.30%） of the strain GJ2008under batchcondition with total sugar at concentration of248.04g·L^-1.Ethanol fermentation was carried out in10L bioreactor under fed-batch condition. The results showed that the ethanol contents were11.6%（v/v） and12.3%（v/v）, respectively andresidual total sugars were16.75g·L^-1and31.75g·L^-1, respectively and the fermentationefficiencies were92.8%and85.54%, respectively, when the strain GJ2008was cultured insugarcane juice with actual total sugar at concentrations of194.11g·L^-1and222.50g·L^-1，respectively.