Study On The Fermentation Capability Of Saccharomyces Cerevisiae GGSF 16 In Very High Gravity Ethanol Fermentation

There are some issues about lowing glucose utilization rate and prolonging fermentation during Very High Gravity ethanol fermentation. Using the secondary fermentation, in this article, to study factors of affecting vitality of Saccharomyces cerevisiae GGSF16, changing yeast fermentation conditions to improve fermentation vitality so as to solve problems in fermentation and to provide the basis for very high gravity fermentation industrialization. Therefore, this paper mainly study the vitality of Saccharomyces cerevisiae GGSF16 and the impact of aerobic during very high gravity ethanol fermentation, conclusions are as follows:(1) To understand the reasons of residual sugar largely and more prolonged in very high gravity alcohol fermentation, we need to compare the affect of glucose concentration to fermentation. Study glucose concentration of 180 g/L, 220 g/L, 260g/L, 300 g/L and 340 g/L to ferment alcohol at 32 ? and 160 rpm. The results show that the optimal glucose concentration is 260 g/L. Improved the initial glucose concentration was significantly higher residual sugar, more decling yeast cells and prolong the fermentation time, ultimately reduce fermentation efficiency.(2) To create a new method of determining yeast vitality for doing determine intuitively and quantitatively. In this study, the 40% volume ratio amount of yeast cells were harvested by centrifuging cultures at 36 h, 42 h, 48 h, 54 h and 60 h during the primary ethanol fermentation and transfered into fresh fermentation medium for secondary fermentation, respectively. By the software graphpad prism 5, the curve of sugar metabolism was plotted during the secondary fermentation and the area under the curve( AUC) of sugar metabolism was calculated. And then the AUC was evaluated quantitatively as a measure of yeast vitality. The results indicated that the ability of sugar metabolism of yeast cell from culture at 36 h?42 h?48 h?54 h and 60 h during the primary fermentation gradually decreased. By secondary fermentation parameter analysis, the results also showed that yeast vitality could be evaluated quantitatively based on the AUC, namely, the less AUC, the stronger yeast vitality,vice verse.(3) In VHG alcohol fermentation late phase, high ethanol concentration make the fermentation vitality of yeast lower, study the effects of ethanol on yeast vitality and provide experimental evidence for the VHG fermentation. The 40% volume ratio amount of yeast cells were harvested by centrifuging cultures at 36 h during the primary ethanol fermentation and transfered equal amounts into 330 g/L glucoseconcentration fresh fermentation medium which added ethanol of 0%, 2%, 4%, 6%and 8% for secondary fermentation. Using the AUC method to calculate value of glucose metabolism, cell growth OD from the secondary fermentation, quantitatively analyze ethanol tolerance and fermentation vitality of Saccharomyces cerevisiae GGSF16 during the stationary phase 36 h primary fermentation. By secondary fermentation parameter analysis, the results also show that Saccharomyces cerevisiae GGSF16 during the stationary phase 36 h primary fermentation can tolerance 4%external ethanol concentration, and the AUC datas also point that added ethanol concentration and cell growth inhibition is proportional, conversely to the yeast fermentation vitality.(4)Increase the total cell through oxygen in VHG fermentation simultaneously,research the impact on the ability of yeast. Through(i) the 40% and 100% volume ratio amount of yeast cells were harvested by centrifuging cultures at the anaerobic and aerobic primary fermentation late phase in flask and transferred into fresh fermentation medium for secondary fermentation, respectively.(ii) compare with anaerobic and aerobic very high gravity ethanol fermentation in 5 L B.Braun fermenter, and(iii) the same amount of yeast cell was harvested by centrifuging culture at 36 h, 42 h, 48 h, 54 h and 60 h during the anaerobic and aerobic primary ethanol fermentation and transfered into fresh fermentation medium for secondary fermentation, respectively. Doing this three assays to research the effect to very high gravity fermentation by aerobic. Comprehensive experimental results show that aerobic can improve fermentation vitality per unit volume by increasing the amount of yeast cells, thereby it can decline residual sugar in fermentation late, accelerate the rate of ethanol generation and short the fermentation time, and improve the efficiency of fermentation, finally.