高温大曲产酯酵母的筛选、鉴定及发酵条件

Screening, identification, and fermentation condition optimization of ester-producing yeast in high-temperature Daqu

摘要:

【背景】高温大曲是酱香型白酒酿造发酵的基础，在整个酿造过程中发挥重要作用，高温大曲中产酯酵母与酒中风味物质的形成密切相关。【目的】筛选获得高温大曲中的产酯酵母，对其发酵特性进行探究。【方法】采用YPD培养基，通过稀释涂布法、形态观察从酱香大曲中对产酯酵母进行初筛、复筛及产酯量的测定，菌株经分子生物学鉴定、产酯影响因素、单因素试验，以及可溶性淀粉、蛋白胨、磷酸二氢钾三因素响应面试验优化发酵条件。【结果】获得5株产酯酵母，其中菌株EY3的产酯量最高，达到2.16 g/L，鉴定结果表明菌株EY3是异常威克汉姆酵母(Wickerhamomyces anomalus)，其最适产酯培养温度为30 ℃、pH 5.0、乙醇浓度为7%、接种量为3%，最佳产酯碳源是可溶性淀粉、氮源是蛋白胨、无机盐是磷酸氢二钾；优化后最大产酯量的培养条件为：可溶性淀粉11.4 g/L、蛋白胨3.0 g/L、磷酸二氢钾0.4 g/L、最大产酯量(3.43±0.22) g/L。【结论】本研究报道了高温大曲中的一株高产酯酵母为异常威克汉姆酵母，对其发酵条件进行了优化，丰富了高温大曲中产酯酵母的多样性。

Abstract:

[Background] High-temperature Daqu is the basis of brewing and fermentation of Maotai-flavor liquor, playing an important role in the whole brewing process. The ester-producing yeast in high-temperature Daqu is associated with the formation of flavor components in liquor. [Objective] To isolate and optimize the fermentation conditions of the ester-producing yeast in high-temperature Daqu. [Methods] We employed the YPD medium, the dilution-coating method, and morphological observation to screen the ester-producing yeast strains in high-temperature Daqu and determine the ester production. After the strain was identified based on molecular evidence, single factor tests and response surface methodology were employed to optimize the fermentation conditions (soluble starch, peptone, and potassium dihydrogen phosphate) of the strain for ester production. [Results] Five ester-producing yeast strains were obtained, in which strain EY3 showcased the highest ester production of 2.16 g/L. Strain EY3 was identified as Wickerhamomyces anomalus, and it demonstrated the highest ester production at 30 ℃, pH 5.0, ethanol concentration of 7%, and inoculation amount of 3%. The optimum carbon source, nitrogen source, and inorganic salt in the medium for ester production by this strain were soluble starch, peptone, and potassium dihydrogen phosphate, respectively. The fermentation conditions for maximum ester production were optimized as 11.4 g/L soluble starch, 3.0 g/L peptone, and 0.4 g/L potassium dihydrogen phosphate, under which the ester production reached (3.43±0.22) g/L. [Conclusion] We screened out a high-yielding ester yeast strain W. anomalus from high-temperature Daqu and optimized the fermentation conditions of this strain, which enriched the diversity of ester-producing yeast.