Programa de Posgrado de Alimentos del Centro de la República (PROPAC), Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas s/n, Col. Las Campanas. C.P. 76010, Querétaro, Querétaro, México.
J Food Sci. 2018 Feb;83(2):419-423. doi: 10.1111/1750-3841.14031. Epub 2018 Jan 16.
The high concentration of fructose in agave juice has been associated with reduced ethanol tolerance of commercial yeasts used for tequila production and low fermentation yields. The selection of autochthonous strains, which are better adapted to agave juice, could improve the process. In this study, a 2-step selection process of yeasts isolated from spontaneous fermentations for tequila production was carried out based on analysis of the growth dynamics in combined conditions of high fructose and ethanol. First, yeast isolates (605) were screened to identify strains tolerant to high fructose (20%) and to ethanol (10%), yielding 89 isolates able to grow in both conditions. From the 89 isolates, the growth curves under 8 treatments of combined fructose (from 20% to 5%) and ethanol (from 0% to 10%) were obtained, and the kinetic parameters were analyzed with principal component analysis and k-means clustering. The resulting yeast strain groups corresponded to the fast, medium and slow growers. A second clustering of only the fast growers led to the selection of 3 Saccharomyces strains (199, 230, 231) that were able to grow rapidly in 4 out of the 8 conditions evaluated. This methodology differentiated strains phenotypically and could be further used for strain selection in other processes.
A method to select yeast strains for fermentation taking into account the natural differences of yeast isolates. This methodology is based on the cell exposition to combinations of sugar and ethanol, which are the most important stress factors in fermentation. This strategy will help to identify the most tolerant strain that could improve ethanol yield and reduce fermentation time.
龙舌兰花蜜中高浓度的果糖已被证明会降低用于生产特基拉酒的商业酵母的乙醇耐受性，并降低发酵产量。选择更适应龙舌兰花蜜的本土菌株可以改善这一过程。在这项研究中，我们对来自特基拉酒自发发酵的酵母进行了 2 步筛选，这一过程基于对高果糖（20%）和乙醇（10%）的组合条件下生长动态的分析。首先，筛选了酵母分离株（605 株），以鉴定耐高果糖（20%）和乙醇（10%）的菌株，得到了 89 株能够在这两种条件下生长的菌株。从这 89 株菌中，获得了在 8 种果糖（从 20%到 5%）和乙醇（从 0%到 10%）组合条件下的生长曲线，并对动力学参数进行了主成分分析和 k-均值聚类分析。所得酵母株系对应于快速、中速和慢速生长者。仅对快速生长者进行第二次聚类，选择了 3 株酿酒酵母（199、230、231），它们能够在 8 种评估条件中的 4 种条件下快速生长。该方法在表型上对菌株进行了区分，可进一步用于其他工艺中的菌株选择。
一种考虑到酵母分离株天然差异的发酵用酵母菌株选择方法。该方法基于细胞暴露于糖和乙醇的组合，这是发酵中最重要的应激因素。该策略将有助于鉴定出最具耐受性的菌株，从而提高乙醇产量并缩短发酵时间。
