高浓度发酵中酵母菌性能调控及优化

Regulation and optimization of yeast performance in very high gravity(VGH) fermentation

高浓度发酵能有效提高乙醇发酵的经济效益,但反应过程中高浓度基质和产物对酵母菌性能抑制作用是限制最终乙醇产率的关键因素。文中通过分析比较了不同基质及产物浓度下的发酵中基质浓度、菌体浓度、乙醇产量的变化规律,确定酵母菌对抑制物的耐受浓度。并对比内源和外源乙醇对于发酵初始12 h酵母菌平均比增长速率和平均乙醇发酵速率的影响,揭示内外源乙醇抑制作用的差异。结果表明,在实验浓度范围内,该酵母菌株发酵基质最大投加浓度为160 g/L,所产乙醇最大浓度为55 g/L;产物乙醇是发酵过程中的首要抑制因素,菌体对发酵初始时所添加乙醇的耐受浓度为70 g/L,内源乙醇对酵母菌的抑制作用大于外源乙醇。

Very high gravity （VHG） fermentation has a bright future as it can greatly increase the capacity of plant, decrease the labor costs and consumption of energy as well. However, the high concentration of substrate and end product exhibits severe inhibition on the performance of yeast during the process of VHG fermentation. The criti- cal inhibition concentration was confirmed through the analysis and comparison of yeast growth and fermentation per- formance under different substrate or product concentrations in the fermentation process, while other parameters were controlled. According to the experiments, within the scope of the tested substrate concentration, the strain of yeast can produce up to 55g/L ethanol, and critical inhibition substrate concentration is 160g/L. The end product-ethanol is the primary factor inhibiting the fermentation. The yeast can tolerate the ethanol with concentration up to 70g/L at the beginning of fermentation, and endogenous ethanol shows greater impacts on yeast performance than exogenous one.