Effects of synthetic microbial communities replacing traditional Muqu on quality of high-temperature Daqu

synthetic microbial community%high-temperature Daqu%high-throughput sequencing%physical and chemical indexes%volatiles substances%tetramethylpyrazine

Traditional high-temperature Daqu is produced by spontaneous fermentation,which has disadvantages including complex composition of microbial community and difficulty in controlling the com-ponents and content of required flavor.Wheat was used to prepare the solid microbial agents of Bacillus li-cheniformis BL44,Saccharomyces cerevisiae SCY62,Paecilomyces variotii PV3,Rhizomucor pusillus RP1 and Thermoascus crustaceus TC1 isolated and screened from the high-temperature Daqu to optimize the structure of microbial community in high-temperature Daqu and improve the quality of high-temperature Daqu.Two synthetic microbial communities were constructed with different addition ratios to replace the traditional Muqu(CK)in producing high-temperature Daqu.Brewing experiments in laboratory were con-ducted and analyzed.The results of high-throughput sequencing showed that the dominant fungal genus and the dominant bacterial genus of the three kinds of Daqu was Lichtheimia and Bacillus,respectively.The re-sults of measuring the physicochemical indexes of the Daqu showed that the liquefaction and saccharification abilities of the high-temperature Daqu inoculated with the synthetic microbial communities were significant-ly improved compared to CK.The results of analyses with gas chromatography-mass spectrometry showed that inoculating synthetic microbial communities instead of traditional Muqu significantly increased the con-tent of tetramethylpyrazine in Daqu and fermented grains.The content of tetramethylpyrazine in Daqu inocu-lated with synthetic microbial group 1 and microbial group 2 was 31.90 mg/kg and 56.73 mg/kg,in-creased by 2.80 and 4.99 times compared to that of CK.In the high-temperature stacked fermentation mash,the content of tetramethylpyrazine inoculated with synthetic microbial group 1 and microbial group 2 was 0.76 mg/kg and 2.74 mg/kg,increased by 4.03 and 14.61 times compared to that of CK.It is indicat-ed that the synthetic microbial community has potential application in directionally regulating the activity of enzymes in Daqu and the components and contents of some specific flavors in Baijiu.