酱香大曲中产四甲基吡嗪细菌的分离鉴定及其功能性研究

采用稀释平板涂布法从酱香型白酒大曲中分离筛选出细菌菌株19株，模拟酱香型白酒生产发酵工艺，获得2株固态发酵产物具有浓郁酱香气味的菌株FBKL1.0199和FBKL1.0201。结合菌株形态学观察、生理生化实验和分子生物学方法，鉴定其为地衣芽孢杆菌（Bacillus licheniformis）。研究发现，菌株FBKL1.0199具有高产蛋白酶的特性，其中性蛋白酶活力达3 925. 80 U/g，酸性蛋白酶活力也相对较高，达139.27 U/g。同时，利用固相微萃取-气质联用技术对菌株FBKL1.0199和FBKL1.0201模拟白酒固态发酵的挥发性香味物质进行分析，发现其中吡嗪类物质相对含量较高，分别为46.01%和48.32%，且均以四甲基吡嗪为主，含量分别为44.11%和47.41%。分离得到的菌株FBKL1.0199和FBKL1.0201可以作为产四甲基吡嗪的功能菌。

Isolation and identification of functional bacteria with high yield of tetramethyl pyrazine from Moutai-flavor high-temperature Daqu

By the methods of spread plate from Moutai-flavor high-temperature Baijiu Daqu, 19 bacterial strains were isolated and screened. Two strains of FBKL1.0199 and FBKL1.0201 with rich Moutai-flavor were obtained by simulation of the Moutai-flavor Baijiu (liquor) fermentation process. Combining with the morphology, physiology of strain with biochemical and molecular biology, the strain was identified as Bacillus licheniformis. It was found that strain FBKL1.0199 had the characteristics of high yield protease, the protease activity was as high as 3 925.80 U/g, and the acid protease activity was also relatively high, reaching 139.27 U/g. At the same time, the volatile flavor compounds produced by strains FBKL1.0199 and FBKL1.0201 were analyzed using HS-SPME and GC-MS. Results showed that the fermentation products had high relative content of pyrazine compounds, which was 46.01% and 48.32%, respectively. The primary components were tetramethyl pyrazine, and the contents were 44.11% and 47.41%, the strains FBKL1.0199 and FBKL1.0201 can be used as the functional bacteria for tetramethyl pyrazine production.