Abstract: This study was aimed at investigating the diversities of culturable yeast and Bacillus during the production of Sichuan Luzhou-flavor Daqu and at analyzing their relationship with process parameters (physicochemical and quality indexes). The process parameters were monitored according to the national light industry standard QB/T 4257-2011, and the selective isolation of yeast and Bacillus from 11 samples was performed by using pure culture technique. A total of 194 yeast strains were obtained and after molecular biological identification, they were assigned to nine genera that belong to the phyla Ascomycota and Basidiomycota, seven of which were clustered into the order Saccharomycetales. A total of 148 strains of Bacillus were obtained and identified as 8 species, with Bacillus subtilis being the dominant one. In addition, the best usage time of Sichuan Luzhou-flavor Daqu was between day 90 and 180 of the production process, and the quality of Daqu decreased greatly with the prolongation of storage period. Redundancy (RDA) analysis showed that physicochemical indexes were mainly negatively correlated with the diversities of yeast and Bacillus. There were six key species contributing to the quality of Daqu, including Kazachstania exigua, Candida tropicalis, Wickerhamomyces anomalus, B. subtilis, B. horneckiae and B. megaterium. There were abundant species diversities of yeast and Bacillus during the production process, and they were not only regulated by the physicochemical indexes during the production process, but also affected the quality of Daqu.

Key words: Luzhou-flavor Daqu, yeast, Bacillus, process parameters, correlation analysis