## 3 Results and Discussion
### Correlation Analysis of Flavor Compounds and Microorganisms  
The dynamic succession and interactions of microorganisms affected the microbial metabolisms that produce the flavor chemicals of Baijiu. Therefore, exploring the relationships between the microorganisms and the formation of flavor compounds was of great significance for guiding the fermentation production of Baijiu [36]. The results indicated that bacterial microorganisms displayed a greater positive correlation with the flavor compounds of Baijiu (Figure 7a-c). In sample 2, _Clostridium sensu strictto_ 12 and _Sporolactobacillus_ showed very significant positive correlations with most of the flavor compounds (Figure 7a). In sample 3, _Sporolactobacillus_, _Clostridium sensu strictto_ 1, _Enterobacter_, _Klebsiella_, _Clostridium sensu strictto_ 11, and _Capriciproducens_ were positively correlated with almost all of the flavor compounds (Figure 7b). In sample 4, _Lactobacillus_, _Sporolactobacillus_, _Clostridium sensu stricto_ 12, _Klebsiella_, _Koskonia_, and _Clostridium sensu stricto_ 1 showed significantly positive correlations with most of the flavor compounds (Figure 7c). A comprehensive analysis found that in all samples, _Sporolactobacillus_ and _Clostridium_ showed significant positive effects on the production of most of the flavor compounds in Baijiu, which was consistent with previously reported studies [42; 46; 47]. Additionally, more positive correlations were identified in sample 3 and sample 4 than in sample 2, and the added functional microorganisms _Clostridium_, _Capriciproducens_ and _Burkholderia_ had positive effects on the synthesis and stability of flavor compounds (Figure 7a-c). The three dominant genera of _Clostridium_ were _Clostridium sensu stricto_ 1, _Clostridium sensu stricto_ 11, and _Clostridium sensu stricto_ 12 (Figure 5a). In sample 2, _Clostridium sensu stricto_ 12 was most positively correlated with flavor compounds, followed by _Clostridium sensu stricto_ 1 and _Clostridium sensu stricto_ 11 (Figure 7a). In sample 3, _Clostridium sensu stricto_ 1 and _Clostridium sensu stricto_ 11 were most closely correlated with flavor compounds, followed by _Clostridium sensu stricto_ 12 (Figure 7b). Sample 4 combined the advantages of sample 2 and sample 3, among which _Clostridium sensu stricto_ 1 and _Clostridium sensu stricto_ 12 showed the most obvious impact on flavor compounds, followed by _Clostridium sensu stricto_ 11. The genus _Burkholderia_ was positively correlated with flavor compound b5 (1-hexanol) in sample 4, and showed a significantly positive correlation with flavor compounds b1 (phenylethyl alcohol), a18 (decanoic acid, ethyl ester), a20 (hexanoic acid, ethyl ester), a19 (hexanoic acid, butyl ester), and a26 (octanoic acid, ethyl ester). While in sample 2 and sample 3, _Burkholderia_ showed a positive impact on these flavor compounds, but not significant, which indicated that the microorganisms in sample 4 had a synergistic effect with _Burkholderia_ and promoted the production of flavor compounds. _Capriciproducens_ had positive effects on most of the flavor compounds in all samples [42; 47; 48], especially in sample 3, it showed an extremely positive effect for a28 (acetic acid ethyl ester), a18 (decanoic acid, ethyl ester) (\(p<0.001\)), and was positively correlated with the other 15 flavor compounds (twelve esters, one ketone, one alkane, one furan) (Figure 7b). In sample 2, the positive correlation between _Caprioicproducens_ and flavor compounds was not significant, but it showed significantly positive effects on a8(9.cis.,11. _trans_-octadecadienoic acid, ethyl ester), f2 (6,10,14-trimethyl-2-pentadecanone), a11 (benzoic acid, ethyl ester), and c1 (2,4-di-tert-butylphenol) in sample 4 (Figure 7c).