Abstract: In this study, high-throughput sequencing technology and statistical analysis were employed to explore the effects of adding green tea at proportions of 10%, 20%, and 30% on the physicochemical characteristics, bacterial community diversity, and succession of daqu fermentation compared to wheat starter (control). The results showed that the addition of green tea significantly increased the bacterial diversity of the daqu community and improved its saccharification ability, moisture content, and acidity. However, the increase in tea addition proportion did not exhibit a proportional relationship with community diversity. The distinctive evolutionary structures of the community systems in different types of daqu were found to be the main factors influencing their physicochemical characteristics. During the fermentation process, the four types of daqu exhibited differentiation in community succession starting from the thermophilic stage, leading to the formation of unique community structures at the end of fermentation. The phyla Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria showed varying influences on the community succession of the four types of daqu, thus driving the appearance of different physicochemical characteristics in each type. Specifically, Pseudomonas was an important contributing bacterial genus in the control and 10% tea-added daqu, while Weissella and Pediococcus, genera of lactic acid bacteria, were important contributors in the 20% tea-added daqu. Bacillus was found to be a significant contributing bacterial genus in the 30% tea-added daqu. This study provides a theoretical basis for process optimization in the production of tea-added daqu and for the development of multi-raw material fermentation starters. It also has implications for improving the daqu preparation process and the application of tea in fermentation.

Key words: community succession, physicochemical parameters, community diversity, community structure, dominant tax