Effect of storage on microbioa and enzyme proteomic profile of low-temperature Daqu

Daqu provides microbiota, flavor substances and enzymes for liquor fermentation. Storage after fermentation is an essential stage for the mature of Daqu. However, it is still unclear about the effect of storage on the microbiota structure and enzyme profile. Here, this work revealed the variation of microbiota structure and enzyme profile after storage of low-temperature Daqu using amplicon sequencing and proteomic profile analysis. Results showed that the content of acidity significantly increased by 13.79% (P <0.05). The saccharification power, liquefaction power and fermentation power significantly increased by 2.90%, 17.32% and 16.04%, respectively (P <0.05). The contents of 3-methyl-1-butanol and 1-octen-3-ol increased by 147.19% and 29.12%, respectively (P <0.05). Lichtheimia, Saccharomyces, Rhizopus, Aspergillus, Pantoea, Lactiplantibacillus, Pichia, Lacticaseibacillus, Pseudomonas, Linnemannia, Levilactobacillus, Pediococcus, Paenibacillus and Lactobacillus were the major enzyme-producing microbiota (average protein abundance >1%) using proteomic profile analysis. After storage, the relative abundances of Lactobacillus and Aspergillus increased from 2.59% to 17.63%, and 7.53% to 33.67% using amplicon sequencing, respectively. The protein abundance of α-amylase produced by Aspergillus increased from 0.05% to 0.11%, and was consistent with variations of the relative abundance of Aspergillus, and the liquefaction power. The protein abundance of lactic acid dehydrogenase produced by Lactobacillus increased from 0.07% to 0.11%, and was consistent with the variation of relative abundance of Lactobacillus. This work revealed the effect of storage on microbioa and enzyme proteomic profile of low-temperature Daqu. It would be beneficial for controlling the storage stage of Daqu, and help improving the quality of Daqu.