廢糟液全循環對自絮凝酵母糖酵解途徑關鍵酶、脅迫相關代謝物及胞內組分的影響

孜力汗，張春明，任劍剛，袁文杰，陳麗杰

大連理工大學生命科學與技術學院，大連 116023

廢糟液全循環對自絮凝酵母糖酵解途徑關鍵酶、脅迫相關代謝物及胞內組分的影響

孜力汗，張春明，任劍剛，袁文杰，陳麗杰

大連理工大學生命科學與技術學院，大連 116023

旨在研究廢糟液直接全循環對絮凝酵母乙醇發酵、糖酵解關鍵酶以及細胞組成的影響。在一有效容積1.5 L的攪拌式生物反應器中，使用葡萄糖為220 g/L，添加8 g/L酵母粉和6 g/L蛋白胨的培養基，以0.04 h?1的稀釋率進行自絮凝顆粒酵母乙醇連續發酵。每隔 3天將收集到的發酵液集中精餾處理，得到的廢糟液用于配制發酵培養基。裝置運行近20 d，實驗結果表明，隨著廢液循環批次的增加，系統乙醇和生物量濃度明顯降低，糖酵解途徑3個關鍵限速酶：己糖激酶、6-磷酸果糖激酶和丙酮酸激酶不同程度受到抑制。為了應對廢糟液中高沸點副產物積累導致的環境脅迫，維持細胞正常代謝，甘油和菌體胞內蛋白生物合成加強，碳水化合物積累減弱。這些研究結果對進一步研究高沸點副產物積累對酵母細胞乙醇發酵影響的機理和菌種的代謝工程改造，具有重要意義。

乙醇發酵，自絮凝酵母，廢糟液循環，高沸點副產物

Abstract:This research aimed to study the effect of distillage recycling on ethanol fermentation, the key glycolytic enzymes and cell composition of the self-flocculating yeast.With the self-flocculating yeast SPSC01 and medium composed of 220 g/L glucose, 8 g/L yeast extract and 6 g/L peptone, continuous ethanol fermentation was carried out at the dilution rate of 0.04 h?1with a 1.5 L tank bioreactor.Fermentation broth was collected every 3 days, and ethanol and other volatile byproducts were removed by distillation, but the stillage with high boiling byproducts was recycled to prepare the medium instead of fresh water.The system was run for 20 days, during which ethanol and biomass concentrations in the effluent decreased continuously, indicating the significant inhibition of the high boiling byproducts accumulated within the system.Thus, the activities of the key enzymes of the glycolytic pathway: hexokinase, 6-phosphofructose kinase, and pyruvate kinase were analyzed, and it was observed that all of them were inhibited.Furthermore, the biosynthesis of the stress response metabolites glycerol and trehalose was investigated, and it was found that glycerol production that can protect yeast cells against osmotic pressure stress was enhanced, but trehalose biosynthesis that can protect yeast cells against ethanol inhibition was not improved, correspondingly.And in the meantime, the biosynthesis of the major intracellular components proteins and hydrocarbons was adjusted, correspondingly.

Keywords:ethanol fermentation, self-flocculating yeast, recycling of distillage, high boiling byproducts

基于生物質資源生產的燃料乙醇可與成品油以一定比例配混或直接使用，不僅可以替代等量成品油，對緩解由于石油資源短缺導致的液體燃料供應緊張具有重要意義[1]。這種混合燃料或純乙醇可以減少發動機尾氣溫室氣體的凈排量，有助于溫室氣體減排[2]。……