摘要
研究发现,通过在发酵培养基中添加0.8mmol/L棕榈酸可将燃料乙醇产量提高12.7%.生长在培养基中分别添加棕榈酸、亚油酸和不添加任何脂肪酸的菌体经过18%(v/v)乙醇冲击7h,酵母存活率分别为39%、5%和0%.生长于不同脂肪酸条件下酵母的细胞膜富含各自所添加的脂肪酸.菌体生长曲线表明在稳定期,生长于添加棕榈酸条件下的菌体的细胞浓度最大.菌体膜透性由大到小排列顺序为:不添加脂肪酸、添加亚油酸、添加棕榈酸;这与菌体乙醇耐性由弱到强的顺序完全一致,这说明菌体乙醇耐性的提高与细胞膜透性维持较低水平存在密切联系.从乙醇生成动力学模型参数分析可知:随着菌体乙醇耐性的增强,细胞的生长速率和细胞浓度对产物生成速率的贡献也在逐渐加强,这说明在发酵培养基中添加棕榈酸对于缩短发酵周期是有可能的.
Investigation was undertaken for the purpose that ethanol yield has been increased to 12.7% when yeast cell grew with exogenously supplemented palmitic acid （0. 8mmol/L） and supplemented 30% original volume of fermentation fluid in last fermentation phase. When exposed to 18% （v/v） ethanol for 7h, yeast ceils which grew with exogenously supplemented fatty acid, such as palmitic, linolenic acid and blank respectively, remained for viability levels of 39%, 5% and 0%. When grown with different supplemented fatty acid, cells of Saccharomyces cerevisiae were rich in the kind of fatty acid added in the plasma membranes. It was showed by the biomass growth curves that yeast got the highest concentration in steady stage when it grew with exogenously supplemented palmitic. Plasma membrane permeability levels of yeast were ranked from the highest to the lowest as： grew with exogenously supplemented palmitic, linolenic acid and blank respectively, precisely corresponding to the ranked order of their ethanol tolerances from the lowest to the highest. Thus, the increased ethanol tolerance of yeast is closely associated with its ability to maintain a lower plasma membrane permeability when cells are exposed to high concentration of ethanol. Kinetics model parameters resulted from curves of ethanol concentration shows that yeast growth rate and cell concentration contributed more to the ethanol produce rate when yeast ethanol tolerance increased. These data suggest that the fermentation period can be curtailed by supplementing palmitic acid.
出处
《应用基础与工程科学学报》
EI
CSCD
2009年第5期697-706,共10页
Journal of Basic Science and Engineering
基金
国家自然科学基金资助项目(20776162)
关键词
细胞膜透性
油莎豆粕
燃料酒精
动力学模型
plasma membrane permeability
Cyperus esculentus meals
ethanol
kinetic models
