Pigeau G M, Inglis D L
Department of Biological Sciences, Cool Climate Oenology and Viticulture Institute, Brock University, St Catharines, ON, Canada.
J Appl Microbiol. 2005;99(1):112-25. doi: 10.1111/j.1365-2672.2005.02577.x.
To determine acetic acid, acetaldehyde and glycerol production by wine yeast throughout Icewine fermentation. The expression of yeast cytosolic aldehyde dehydrogenases (ALD3 and ALD6) and glycerol-3-phosphate dehydrogenase (GPD1) were followed to relate metabolites in the wines to expression patterns of these genes.
Icewine juice (38.8 degrees Brix, 401 +/- 7 g l(-1) sugar), diluted Icewine juice (21.3 degrees Brix, 211 +/- 7 g l(-1) sugar) and the diluted juice with sugar levels equal to the original Icewine juice (35.6 degrees Brix, 402 +/- 6 g l(-1) sugar) were fermented in triplicate using the commercial wine yeast K1-V1116. Acetic acid production increased 7.1-fold and glycerol production increased 1.8-fold in the Icewine fermentation over that found in the diluted juice fermentation. ALD3 showed a 6.2-fold induction and GPD1 showed a 2.5-fold induction during Icewine vs the diluted fermentation. ALD3 was not glucose repressed when additional sugar was added to diluted juice, but was upregulated 7.0-fold.
The NAD+-dependant aldehyde dehydrogenase encoded by ALD3 appears to contribute to acetic acid production during Icewine fermentation. Expression of GPD1 was upregulated in high sugar fermentations and reflects the elevated levels of glycerol. Solutes in Icewine juice in addition to sugar contribute to the yeast metabolic response.
This work represents the first descriptive analysis of the fermentation of Canadian Icewine, the expression patterns of yeast genes involved in metabolite production, and their impact on Icewine quality. A role for ALD3 in acetic acid production during Icewine fermentation was found.
测定冰酒发酵过程中葡萄酒酵母产生乙酸、乙醛和甘油的情况。追踪酵母胞质醛脱氢酶（ALD3和ALD6）以及3-磷酸甘油脱氢酶（GPD1）的表达，以将葡萄酒中的代谢物与这些基因的表达模式联系起来。
使用商业葡萄酒酵母K1-V1116对冰酒汁（38.8°白利糖度，401±7 g l⁻¹糖）、稀释的冰酒汁（21.3°白利糖度，211±7 g l⁻¹糖）以及糖分水平与原始冰酒汁相等的稀释汁（35.6°白利糖度，402±6 g l⁻¹糖）进行三次重复发酵。与稀释汁发酵相比，冰酒发酵过程中乙酸产量增加了7.1倍，甘油产量增加了1.8倍。与稀释发酵相比，冰酒发酵过程中ALD3的诱导倍数为6.2倍，GPD1的诱导倍数为2.5倍。当向稀释汁中添加额外的糖时，ALD3不受葡萄糖抑制，而是上调了7.0倍。
由ALD3编码的NAD⁺依赖性醛脱氢酶似乎在冰酒发酵过程中对乙酸的产生有贡献。GPD1的表达在高糖发酵中上调，反映了甘油水平的升高。除了糖之外，冰酒汁中的溶质也有助于酵母的代谢反应。
这项工作首次对加拿大冰酒的发酵、参与代谢物产生的酵母基因表达模式及其对冰酒品质的影响进行了描述性分析。发现了ALD3在冰酒发酵过程中对乙酸产生的作用。
