Mouret J R, Cadiere A, Aguera E, Rollero S, Ortiz-Julien A, Sablayrolles J M, Dequin S
INRA, UMR1083, Montpellier, France.
Yeast. 2015 Jan;32(1):257-69. doi: 10.1002/yea.3028. Epub 2014 Aug 6.
We performed a dynamic and quantitative analysis of the synthesis of fermentative aromas by an aromatic wine yeast, ECA5, obtained by adaptive evolution. During fermentation at pilot scale on synthetic and natural musts, ECA5 produced volatile compounds (higher alcohols and their acetates, ethyl esters) at higher rates than the ancestral strain, with the exception of propanol. Marked differences in the chronology of synthesis of several compounds were observed between the two strains. Overproduction of phenyl ethanol occurred mainly during the growth phase for ECA5, consistent with its higher flux through the pentose phosphate pathway, which plays a key role in biosynthetic processes. The kinetics of production of isobutanol and isoamyl alcohol were differently affected by different media (synthetic or natural must) and, in particular, according to the nature of the sterols in the media (ergosterol or phytosterols). We also observed differences in the chronology of synthesis of ethyl acetate and isoamyl acetate or ethyl esters, suggesting that the regulation of the synthesis of these compounds in the evolved strain differs from that in the ancestral strain. This study shows that a dynamic analysis of volatile compounds, using high acquisition frequency online gas chromatography, can provide novel insights into the synthesis and regulation of aromas and is thus a potentially powerful tool for strain characterization.
我们对通过适应性进化获得的一种芳香型葡萄酒酵母ECA5发酵香气的合成进行了动态定量分析。在中试规模下对合成葡萄汁和天然葡萄汁进行发酵时,除丙醇外,ECA5产生挥发性化合物(高级醇及其乙酸酯、乙酯)的速率高于原始菌株。在两种菌株之间观察到几种化合物合成时间顺序上的显著差异。苯乙醇的过量产生主要发生在ECA5的生长阶段,这与其通过磷酸戊糖途径的通量较高一致,磷酸戊糖途径在生物合成过程中起关键作用。异丁醇和异戊醇的产生动力学受到不同培养基(合成葡萄汁或天然葡萄汁)的不同影响,特别是根据培养基中甾醇的性质(麦角甾醇或植物甾醇)。我们还观察到乙酸乙酯和乙酸异戊酯或乙酯合成时间顺序上的差异,这表明进化菌株中这些化合物合成的调控与原始菌株不同。这项研究表明,使用高采集频率在线气相色谱对挥发性化合物进行动态分析,可以为香气的合成和调控提供新的见解,因此是菌株表征的一种潜在有力工具。