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pH值是影响酵母乙醇发酵的重要因素。应用拉曼光谱初步分析不同初始pH值对乙醇发酵过程的影响。结果显示:1)在3.0、4.5、6.5三个不同初始pH值的培养基中,pH 4.5下乙醇产量最高,pH 3.0下最低。2)在发酵的前15h,不同初始pH值下的酵母细胞生物大分子的拉曼信号变化波动大;后期,pH 3.0下胞内脂类和蛋白质的拉曼信号最强,pH 6.5最弱;显示在低pH值环境下部分底物可能被转化为胞内储藏物质。3)主成分分析显示,pH值对酵母细胞生理状态的影响从发酵的初始阶段就开始;1440cm-1和1600cm-1峰一直是影响主成分PC1、PC2、PC3分值的主要特征峰;说明pH环境可能影响了酵母细胞的脂类物质合成和细胞的呼吸代谢,进而影响了底物的代谢方向和产物的合成。结果表明,拉曼光谱和单细胞分析可以用于剖析微生物发酵过程的生理机制,为乙醇发酵提供全新的参考信息。
pH value is an important factor affecting yeast ethanol fermentation. Raman spectroscopy preliminary analysis of different initial pH on the ethanol fermentation process. The results showed that: 1) In 3.0, 4.5, 6.5 medium with different initial pH, ethanol yield was the highest at pH 4.5 and lowest at pH 3.0. 2) The Raman signal of yeast cell biomacromolecule fluctuated greatly at different initial pH values in the first 15 h of fermentation. In the late stage, the Raman signal of intracellular lipids and proteins was strongest at pH 3.0 and the pH value was the weakest at pH 6.5. Some substrates may be converted to intracellular storage material at low pH. 3) The principal component analysis showed that the effect of pH value on the physiological state of yeast cells started from the initial stage of fermentation. The 1440cm-1 and 1600cm-1 peaks were the main characteristic peaks that affect the main components PC1, PC2 and PC3. The pH environment may affect lipid synthesis and cellular respiratory metabolism of yeast cells, thereby affecting the metabolic direction of the substrate and the product synthesis. The results show that Raman spectroscopy and single cell analysis can be used to analyze the physiological mechanism of microbial fermentation process, providing new reference information for ethanol fermentation.