## 3 Results and Discussion
### Microbial Community Analysis
#### 3.2.2 Microbial Interactions during Fermentation
_Byssochlamys_ showed an inhibitory relationship with _Weissella_ and unclassified_Lactobacillus, and positive interaction with _Amphibacillus_, _Baravitiococcus_, _Clostridium_ sensu stricto 18, and no-rank_Bacillaceae. _Saccharomyces_ showed negative interaction with _Rhodococcus_, unclassified_Nocardioidaceae, and positive interaction with _Pediococcus_, _Weissella_, _Streptomyces_, _Saccharomycespora_, _norank_Pseudonocardiaceae_, and unclassified_Lactobacillus_ (Figure 7c). Results of 3 dominant bacterial genera with fungi showed that _Lactobacillus_ showed negative interaction with _Cytofibolsidium_ and _Cyberlindnera_ and positive interaction with _Leitothecium_, _Rasamsonia_, _Miceoscus_, _Debaryomyces_, _Apiotrichum_, _Lichtheima_, _Cutaneotrichosporon_, _Mucor_ and _Pithoascus_ (Figure 7d). _Ocanobacillus_ showed negative interaction with _Saccharomyces_, _Wickerhamomyces_, _Kodamaea_, _Hyhopichia_, _Candida_, _Millerozyma_, _Mucor_, and _Dekkera_, and positive interaction with _Monascus_, unclassified_Saccharomyces_, _Naganishia_, and _Cystofilobosidium_. _Virgibacillus_ showed negative interaction with _Saccharomyces_, _Wickerhamomyces_, _Kodamaea_, _Hyhopichia_, _Candida_, _Mucor_, and _Dekkera_ and positive interaction with _Monascus_ and _Cystofilobosidium_ (Figure 7d). Based on the correlation analysis, it could be concluded that due to the adaptability of _Lactobacillus_ to the sauce-flavor Baiju fermentation system, its abundance increased significantly in the middle and late stages of fermentation on each round. Due to the potential nutritional competition and the significant negative correlation between _Lactobacillus_ and other bacteria (Figure 7a), _Lactobacillus_ became the dominant genus of bacteria and inhibited the growth of other bacterial genera. _Issatchenkia_ only showed a negative correlation with a few fungal genera, and _Byssochlamys_, another fungal genus with relatively high abundance, showed positive correlations with most of the fungal genera (Figure 7b). Therefore, there was no one fungal genus dominated in a long fermentation time. The study of microbial interaction is very important for the establishment of a complex and stable co-microbial fermentation system [30]. For the complex fermentation system with multiple microorganisms, how to effectively control the stability and achieve products with stable flavor and quality among batches is still a challenge that enterprises are facing [31]. Based on the high-throughput analysis and functional microorganism, studies realized the stable production of cheese, another co-microbial fermented food, and showed that the core functional microorganisms had the ability to drive the stable fermentation of the entire system [32]. However, for most of the complex microbial fermented foods, the relevant studies are still relatively simple. How to excavate and determine the core functional microorganisms of Baijiu were proposed in previous studies with standards [2]. However, how these core microorganisms achieve the succession of microbial composition and abundance through interaction, as well as synthesize specific types of flavor substances with stable contents, still needs to be well studied. The clarity of relevant problems will help to promote the stability and quality of fermented food and is also the key to solving the problem of batch instability in the production of multi-microbial fermented food [31].