产乙偶姻菌株的分离鉴定及其对固态混菌发酵产物的影响

Isolation and identification of acetoin-producing strain and its effect on solid-state multi-microbial fermentation products

乙偶姻(ACT)是白酒中重要功能物质四甲基吡嗪(TTMP)的关键前体物,该研究从酱香型大曲中筛选分离产乙偶姻菌株,结合形态学观察及分子生物学技术对其进行鉴定,并将其应用于固态混菌发酵,考察其对发酵产物理化指标、有机酸及挥发性风味物质的影响。结果表明,分离筛选出一株产乙偶姻菌株A12F_C118,经鉴定其为索诺拉沙漠芽孢杆菌(Bacillus sonorensis)。添加菌株A12F_C118混菌发酵产物中,水分、还原糖、总酸、pH值分别比空白组分别提高了39.40%、38.46%、127.63%、11.93%;添加菌株A12F_C118混菌发酵产物中共检出挥发性风味物质51种,其中正戊醇、苯乙酸乙酯、己酸乙酯、四甲基吡嗪、2,5-二甲基吡嗪和三甲基吡嗪等重要风味物质含量均有所增加。菌株A12F_C118对固态混菌发酵过程中草酸、L-苹果酸、L-乳酸、乙酸、柠檬酸的合成皆有促进作用,但对琥珀酸的影响不明显。

Acetoin(ACT)is a key precursor of tetramethylpyrazine(TTMP),an important functional substance in Baijiu.Acetoin-producing strains were screened and isolated from sauce-flavor Daqu,identified by morphological observation and molecular biology techniques,and applied to solid-state multi-microbial fermentation to investigate their effects on physicochemical indexes,organic acids,and volatile flavor compounds of fermentation products.The results showed that an acetoin-producing strain A12F_C118 was isolated and screened,and identified as Bacillus sonorensis.The moisture reducing sugar,total acid contents,and pH of the multi-microbial fermentation products with strain A12F_C118 addition increased by 39.40%,38.46%,127.63%,and 11.93%,respectively compared with the blank group.A total of 51 volatile flavor compounds were detected in the multi-microbial fermentation products with strain A12F_C118 addition,among them,the contents of important flavor compounds such as 1-pentanol,ethyl phenylacetate,ethyl caproate,tetramethylpyrazine,2,5-dimethylpyrazine and trimethylpyrazine increased.Strain A12F_C118 could promote the synthesis of oxalic acid,L-malic acid,L-lactic acid,acetic acid and citric acid during solid-state multi-microbial fermentation,but its effect on succinic acid was not significant.