Li Hua, Su Jing, Ma Wen, Guo Anque, Shan Zuhua, Wang Hua
College of Enology, Northwest A&F University, Yangling, Shannxi 712100, China Shaanxi Engineering Research Center for Viti-Viniculture, Yangling, Shaanxi 712100, China Heyang Experimental and Demonstrational Stations for Grape, Weinan, Shaanxi 715300, China.
College of Food Science and Engineering, Northwest A&F University, Yangling, Shannxi 712100, China.
FEMS Yeast Res. 2015 Mar;15(2). doi: 10.1093/femsyr/fou010. Epub 2015 Mar 10.
A sealed fermentation (SF) system and an anaerobic fermentation (AF) system (under normal atmospheric pressure conditions) were employed to study the influence of endogenous carbon dioxide (CO2) on the metabolism of Saccharomyces cerevisiae. The results showed that the fermentation stopped when 82.0 g L(-1) glucose was consumed and the endogenously produced CO2: pressure reached to 14.3 MPa in SF system, while the sugar was used up during AF. The total yeast viable count in the end of AF was higher than that of SF. It was also observed that the ethanol yield in AF and SF was similar, the glycerol yield in AF was 1.26 times higher than that in SF, while the succinic acid and acetic acid yields in SF were 24.7 and 26 times higher than that in AF, respectively. Additionally, this work provides a stoichiometric model used for metabolic flux analysis of S. cerevisiae to compare the flux distribution in SF and AF. The results showed that CO2 had an important effect on the pathways of oxaloacetic acid formation from pyruvic acid and ribose-5-phosphate formation from glucose-6-phosphate. However, the pathway of ethanol formation from pyruvic acid (decarboxylation reaction), catalyzed by pyruvate decarboxylase, was insensitive to CO2.
采用密封发酵（SF）系统和厌氧发酵（AF）系统（在常压条件下）研究内源性二氧化碳（CO₂）对酿酒酵母代谢的影响。结果表明，在SF系统中，当消耗82.0 g L⁻¹葡萄糖且内源性产生的CO₂压力达到14.3 MPa时发酵停止，而在AF过程中糖被耗尽。AF结束时的酵母总活菌数高于SF。还观察到，AF和SF中的乙醇产量相似，AF中的甘油产量比SF高1.26倍，而SF中的琥珀酸和乙酸产量分别比AF高24.7倍和26倍。此外，这项工作提供了一个用于酿酒酵母代谢通量分析的化学计量模型，以比较SF和AF中的通量分布。结果表明，CO₂对丙酮酸形成草酰乙酸以及葡萄糖-6-磷酸形成核糖-5-磷酸的途径有重要影响。然而，由丙酮酸脱羧酶催化的丙酮酸形成乙醇的途径（脱羧反应）对CO₂不敏感。
