Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México.
J Biosci Bioeng. 2012 May;113(5):614-8. doi: 10.1016/j.jbiosc.2011.12.015. Epub 2012 Jan 26.
In tequila production, fermentation is an important step. Fermentation determines the ethanol productivity and organoleptic properties of the beverage. In this study, a yeast isolated from native residual agave must was identified as Kluyveromyces marxianus UMPe-1 by 26S rRNA sequencing. This yeast was compared with the baker's yeast Saccharomyces cerevisiae Pan1. Our findings demonstrate that the UMPe-1 yeast was able to support the sugar content of agave must and glucose up to 22% (w/v) and tolerated 10% (v/v) ethanol concentration in the medium with 50% cells survival. Pilot and industrial fermentation of agave must tests showed that the K. marxianus UMPe-1 yeast produced ethanol with yields of 94% and 96% with respect to fermentable sugar content (glucose and fructose, constituting 98%). The S. cerevisiae Pan1 baker's yeast, however, which is commonly used in some tequila factories, showed 76% and 70% yield. At the industrial level, UMPe-1 yeast shows a maximum velocity of fermentable sugar consumption of 2.27g·L(-1)·h(-1) and ethanol production of 1.38g·L(-1)·h(-1), providing 58.78g ethanol·L(-1) at 72h fermentation, which corresponds to 96% yield. In addition, the major and minor volatile compounds in the tequila beverage obtained from UMPe-1 yeast were increased. Importantly, 29 volatile compounds were identified, while the beverage obtained from Pan1-yeast contained fewer compounds and in lower concentrations. The results suggest that the K. marxianus UMPe-1 is a suitable yeast for agave must fermentation, showing high ethanol productivity and increased volatile compound content comparing with a S. cerevisiae baker's yeast used in tequila production.
在龙舌兰酒生产中，发酵是一个重要的步骤。发酵决定了饮料的乙醇生产率和感官特性。在这项研究中，通过 26S rRNA 测序，从本地残余龙舌兰汁中分离出的酵母被鉴定为 Kluyveromyces marxianus UMPe-1。将这种酵母与酿酒酵母 Saccharomyces cerevisiae Pan1 进行了比较。我们的研究结果表明，UMPe-1 酵母能够支持龙舌兰汁和葡萄糖的糖含量高达 22%（w/v），并且在含有 50%细胞存活率的介质中耐受 10%（v/v）的乙醇浓度。龙舌兰汁的中试和工业发酵试验表明，K.marxianus UMPe-1 酵母产生的乙醇分别达到发酵糖含量（葡萄糖和果糖，占 98%）的 94%和 96%。然而，在一些龙舌兰酒工厂中常用的酿酒酵母 Saccharomyces cerevisiae Pan1 仅产生 76%和 70%的产量。在工业水平上，UMPe-1 酵母的最大发酵糖消耗速度为 2.27g·L(-1)·h(-1)，乙醇生产速度为 1.38g·L(-1)·h(-1)，在 72h 发酵时提供 58.78g 乙醇·L(-1)，产率为 96%。此外，从 UMPe-1 酵母获得的龙舌兰酒中的主要和次要挥发性化合物增加了。重要的是，鉴定出了 29 种挥发性化合物，而从 Pan1-酵母获得的饮料则含有较少的化合物，且浓度较低。结果表明，K.marxianus UMPe-1 是一种适合龙舌兰汁发酵的酵母，与用于龙舌兰酒生产的酿酒酵母 Saccharomyces cerevisiae Pan1 相比，具有较高的乙醇生产率和增加的挥发性化合物含量。
