Keystone microbes affect the evolution and ecological coexistence of the community via species/strain specificity

Unraveling the unique microbiota and metabolites in three different colors Jiangqu through multidimensional analysis

Tri-colored Jiangqu, including white (WQ), yellow (YQ), and black (BQ)-color Daqu, significantly influence fresh Baijiu yield and quality. The differences in attributes of these Jiangqu types, sourced from two renowned Baijiu enterprises, were investigated using multi-omics approaches. Color intensity negatively correlated with ammonia nitrogen content, but positively with pyroglutamic acid content. 182 volatiles and 291 non-volatiles were identified, with each types exhibiting unique metabolites. Esters, pyrazines, ketones and phenols were predominant in WQ, YQ, and BQ, respectively. The content of peptides, amines, and amino acids with derivatives also showcased the differences of microbiota and metabolic pathways among tri-colored Jiangqu. BQ's characteristic components of L-Tyrosine and acetyl tributyl citrate were closely associated with melanin formation. In YQ, Scopulibacillus and Rhizopus correlated positively with tetramethylpyrazine. Moreover, the bacterial community significantly influenced the metabolic profiles, and synergistic interactions between fungal and bacterial communities were crucial in determining metabolite abundance.

Revealing the influence of exogenously inoculated Bacillus spp. on the microbiota and metabolic potential of medium-temperature Daqu: A meta-omics analysis

To determine the unique contribution of the bioturbation to the properties of the medium-temperature Daqu, we investigated the differences in microbiota and metabolic composition using the meta-omics approach. Bioturbation increased the amounts of microbial specie and influenced the contribution of the core microbiota to the metabolome. Specifically, inoculated synthetic microbiota (MQB) enhanced the abundance of Bacillus amyloliquefaciens, while Bacillus licheniformis (MQH) increased the abundance of the two Aspergillus species and four species level of lactic acid bacteria. These changes of the microbial profiles significantly increased the potentials of carbohydrate metabolism, amino acid metabolism, and biosynthesis of ester compounds. Consequently, both patterns significantly increased the content of volatile compounds and free amino acids, which were 27.61% and 21.57% (MQB), as well as 15.14% and 17.83% (MQH), respectively. In addition, the contents of lactic acid in MQB and MQH decreased by 65.42% and 42.99%, respectively, closely related to the up- or down-regulation of the expression of their corresponding functional enzyme genes. These results suggested that bioturbation drove the assembly of the core microbiota, rather than becoming critical functional species. Overall, our study provides new insights into the functional role of exogenous isolates in the Daqu microecosystem.

Response of microbiota to exogenous inoculation improved the enzymatic activities of medium-temperature Daqu

To explore the potential mechanism of improving enzymatic activities in medium-temperature Daqu (MTD) by inoculation functional isolates, we inoculated a single strain of Bacillus licheniformis, and the microbiota composed of Bacillus velezensis and Bacillus subtilis in MTD to investigate the association between the response of the functional microbiota and the enzymatic activity. The results showed that the bacterial community of MTD might be more sensitive to bioturbation than the fungal community, and the indigenous microbiota responded to the single strain more than to the microbiota. Moreover, the differential microorganisms mainly included Lactobacillales, Bacillales, and Saccharomycetales between the conventional and fortified samples. Notably, the composition of functional microbiota related to liquefying activity (LA) and saccharifying activity (SA) were significantly different, changing from Lactobacillus and Rhizomucor to Bacillus, Weissella, and Hyphopichia. That might be closely related to the effect of the bioturbation on LA (31.33%) and SA (43.54%) associated microorganisms was more tellingly. Furthermore, the relative abundance changes of bioturbation-sensitive modules in the co-occurrence network might also lead to the difference in enzymatic activities. Therefore, the LA and SA of MTD were improved by bioturbation significantly. These results provide diverse insights into the exogenous functional isolates to regulate the MTD microbiota and improve enzymatic activities.