Fermentation microbiota is specific microorganisms that generate different types of metabolites in many productions. In traditional solid-state fermentation, the structural and functional changes in core microbiota influence the quality and quantity of products. As typical food fermentation, Chinese Maoti-flavor liquor production has the particular mechanism with complex microorganisms and wide variety of metabolites. However, it remains unclear that species succession and function shift of core microbiota in this traditional food fermentation. Here, high-throughput amplicons (16S rRNA gene amplicons sequencing and internal transcribed space amplicons sequencing) and metatranscriptomics sequencing technologies are combined to reveal the structure and function of core microbiota in Chinese Maoti-flavor liquor production. In addition, ultra-performance liquid chromatography and headspace-solid phase microextraction-gas chromatography-mass spectrometer are employed to quality and qualitative analysis the major flavor metabolities. Amplicons analysis indicates species distribution of core micorbiota includes 10 fungal and 11 bacterial genera. Besides, metatranscriptomic analysis indicates pyruvate metabolism in yeasts (genera Pichia, Schizosaccharomyces, Saccharomyces and Zygosaccharomyces) and lactic acid bacteria (genus Lactobacillus) reflects different stages in production of flavor components. Overall, these findings have shown that there are two stages in production. Stage I is high-level alcohol (ethanol) production period that genus Schizosaccharomyces serves as the core functional microorganism. Stage II is high-level acid (lactic acid and acetic acid) production period that genus Lactobacillus serves as the core functional microorganism. Furthermore, functional shift from genus Schizosaccharomyces to genus Lactobacillus drives flavor components conversion from alcohol (ethanol) to acid (lactic acid and acetic acid) in Chinese Maotai-flavor liquor production. This study provides new attempts to understand the effects of core functional microbiota in Chinese Maotao-flavor liquor production and explore the fermentation microbiota under different environmental conditions further.

Many microorganisms in the environment participate in the fermentation process of Chinese liquor. However, it is unknown to what extent the environmental microbiota influences fermentation. In this study, high-throughput sequencing combined with multiphasic metabolite target analysis was applied to study the microbial succession and metabolism changes during Chinese liquor fermentation from two environments (old and new workshops). SourceTracker was applied to evaluate the contribution of environmental microbiota to fermentation. Results showed that Daqu contributed 9.10 to 27.39% of bacterial communities and 61.06 to 80.00% of fungal communities to fermentation, whereas environments (outdoor ground, indoor ground, tools, and other unknown environments) contributed 62.61 to 90.90% of bacterial communities and 20.00 to 38.94% of fungal communities to fermentation. In the old workshop, six bacterial genera (Lactobacillus[11.73% average relative abundance],Bacillus[20.78%],Pseudomonas[6.13%],Kroppenstedtia[10.99%],Weissella[16.64%], andPantoea[3.40%]) and five fungal genera (Pichia[55.10%],Candida[1.47%],Aspergillus[10.66%],Saccharomycopsis[22.11%], andWickerhamomyces[3.35%]) were abundant at the beginning of fermentation. However, in the new workshop, the change of environmental microbiota decreased the abundances ofBacillus(5.74%),Weissella(6.64%),Pichia(33.91%),Aspergillus(7.08%), andWickerhamomyces(0.12%), and increased the abundances ofPseudomonas(17.04%),Kroppenstedtia(13.31%),Pantoea(11.41%),Acinetobacter(3.02%),Candida(16.47%), andKazachstania(1.31%). Meanwhile, in the new workshop, the changes of microbial community resulted in the increase of acetic acid, lactic acid, malic acid, and ethyl acetate, and the decrease of ethyl lactate during fermentation. This study showed that the environmental microbiota was an important source of fermentation microbiota and could drive both microbial succession and metabolic profiles during liquor fermentation.IMPORTANCETraditional solid-state fermentation of foods and beverages is mainly carried out by complex microbial communities from raw materials, starters, and the processing environments. However, it is still unclear how the environmental microbiota influences the quality of fermented foods and beverages, especially for Chinese liquors. In this study, we utilized high-throughput sequencing, microbial source tracking, and multiphasic metabolite target analysis to analyze the origins of microbiota and the metabolic profiles during liquor fermentation. This study contributes to a deeper understanding of the role of environmental microbiota during fermentation.