白酒发酵高糖化性能霉菌的筛选及鉴定

Screening and Identification of Mold Strains with High Saccharifying Properties for Improving Ethanol Fermentation Efficiency in Liquor Production

以不同香型大曲为筛选源分离出霉菌96株,在透明圈法初筛、糖化力测定法复筛的基础上,以清香大曲和糖化酶为对照,模拟白酒酒精发酵过程,将酿酒酵母与霉菌纯种曲混合发酵,以出酒率作为评判指标,从中筛选出1株优质霉菌Rh-07。其纯种曲糖化力、发酵结束后培养基中酒精浓度、出酒率分别为2657.00 U/g、15.40 mL/100 g、42.73%;且以Rh-07纯种曲为糖化剂,其发酵速度基本与对照大曲一致。采用传统微生物学和现代分子生物学的方法对Rh-07进行了鉴定,初步确定为Rhizopus oryzae。同时发现,霉菌糖化酶活力大小与其在酒精发酵中的作用不成严格的正相关关系;在评价霉菌在白酒酒精发酵过程中作用时,不能单纯以糖化酶作为评价指标,应以原料与霉菌作用后的整个物系对酒精发酵作用作为评价指标。

96 mold strains were isolated from Daqu of different flavor types, then based on primary screening by transparent circle method and secondary screening by determination method with Fen-flavor Daqu and saccharifying enzyme as control samples, Saccharomyces cerevisiae mixed with pure mold species for fermentation with liquor yield used as assessment index to screen out a suitable strain named strain Rh-07. Its glucoamylase activity, its ethanol concentration in culture mediums after the fermentation, and its liquor yield were 2657.00 U/g, 15.40 mL/100 g and 42.73 %, respectively. Besides, its fermentation speed was close to control Daqu. Strain Rh-07 was identified as Rhizopus oryzae through 26 s rDNA analysis and morphology observation. Meanwhile, it was revealed that glucoamylase activity of mold strains had positive correlations with its roles in ethanol fermentation. During the evaluation on the roles of mold strain in ethanol fermentation, saccharifying enzyme was not recom- mended as the assessment index, but the effects of the action between mold and raw materials on ethanol fermentation was used as the assessment index.