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Ultra-high concentrations of glucose by yeast fermentation to ethanol, ultra-high-concentration ethanol fermentation, and the resulting economic benefits due to the potential to improve the end of fermentation ethanol concentration, and thus, this fermentation caused strong interest since it was proposed. However, to successfully carry out the ultra-high-concentration ethanol fermentation, still need to solve some challenging problems. One of the biggest problems is one of yeast by the ultra-high-concentration ethanol fermentation due to harsh conditions, such as high osmotic pressure and strong product inhibition of stress was generated, bacterial growth was strongly inhibited even a large number of deaths, eventually leading to fermentation stop. Therefore, how to improve the fermentation process, in order to improve and maintain the viability of the yeast in this stress condition is very important. To this end, the paper will be consolidated to optimize the ultra-high-concentration ethanol fermentation process and explore ventilation fed-batch fermentation process as the focus of the study. In this work, the self-flocculating yeast fusion - Schizosaccharomyces pombe and Saccharomyces cerevisiae strains as the research object. Experiment First Response surface methodology to optimize the fermentation process conditions obtained based on the starting glucose concentration of 300 g · L -1 ultra-high-concentration ethanol fermentation optimum conditions: 300 g · L < sup> -1 glucose, 16.82 g · L . -1 (NH4) 2SO4, 8.24 g · L -1 KH 2 PO 4, 0.50 g L -1 CaCl2, 2.00 g · L -1 MgSO4, 0.08 g · L -1 ZnSO4, 6.00 g · L -1 yeast extract paste, 6.00 g · L -1 protein peptone, inoculum 11%, temperature 30 ° C. The optimized experimental measured at the end of fermentation ethanol concentration mean up to 137.7, g L -1 , compared to unoptimized increased by 28%. The concentration of ethanol in the end predict the optimal results for the 137.9, g L -1 , close to the measured value. At the same time, optimized fermentation period shortened from 72 h to 60 h, the ethanol yield from 1.49 g L -1 · h -1 significantly increased to 2.30 g · L < sup> -1 · h -1 . As far as we know, in 300 g · L -1 starting glucose concentration conditions to carry out the ultra-high-concentration ethanol fermentation usually accumulate a lot of residual sugar and the end of the ethanol concentration is low. However, the end of the study ethanol concentration reached 137.7 g L -1 , the conversion of glucose utilization rate of 96.6%, achieved good experimental results. Based on the results of the process optimization, fermentor experiments, but further investigation ventilation of ultra-high-concentration ethanol fermentation, and further improve the fermentation conditions by adjusting the ventilation strategy (ventilation rate and ventilation). Experiment to get the best ventilation strategy: full ventilation of 10 L · h -1 aeration rate, the end of fermentation ethanol concentration of 127.3 g · L -1 , and not compared to the aerobic fermentation, a 10% increase. Shorten the fermentation period to 39 h, significantly improve the ethanol yield from 2.42 g · L -1 · h -1 to 3.26 g · L -1 · h -1 , a 35 percent increase. At the same time, research suggests that ultra-high-concentration ethanol fermentation by-products (glycerin) the amount of generated yeast cells may have a protective effect for the high concentration of glucose or a high concentration of ethanol in yeast. Finally, in the aerobic fermentation process based on a combination of fed-batch fermentation. Initial glucose concentration were first investigated for fed-batch fermentation, the results show that the initial glucose concentration of 100 g · L -1 , fermentation conditions better than 150 g · L -1 and 200 g · L -1 . And on this basis, to further examine the impact of ventilation and fermentation of active substances for fed-batch fermentation experiments show that the fermentation process of ventilation and the additional fermentation active substances can improve the activity of yeast fermentation of ethanol tolerance, thus significantly improved fermentation position. Ultimately determine the best strategy of the ultra-high-concentration ethanol fermentation ventilation feeding: the initial glucose concentration of 100 g · L -1 , the fermentation process to 0.8 mL · min -1 < / sup> Speed ??Continuous additional optimization culture medium, aeration rate to 10 L · h -1 , a result, the maximum ethanol concentration reached 143.3 g · L -1 , batch fermentation than the ventilation increased 13%.
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