Microbial Ecology of Traditional Chinese Liquor Fermentation

Traditional Chinese liquor fermentation relies on intricate microbial ecosystems within solid-state processes. These ecosystems comprise diverse bacteria (Firmicutes, Actinobacteria, Proteobacteria), yeasts (Saccharomyces, Pichia) and filamentous fungi (Aspergillus, Thermomyces), which originate from starters, pit walls and ambient environment. Initial stages are dominated by saccharifying organisms that convert starch into sugars, notably Bacillus and Rhizopus species in daqu starters. Subsequent succession sees yeast-driven ethanol production followed by lactic acid bacteria metabolism, generating acids and esters that underpin aroma profiles. Pit mud microbiota contribute caproic acid via Clostridial species, enhancing strong-flavour liquors. Environmental reservoirs such as fermentation vessels and air supply key strains that influence consistency and seasonal variation. Advances in high-throughput sequencing and metatranscriptomics have delineated core functional microbiota and metabolic pathways, revealing stage-specific gene expression for alcohol, acid and ester synthesis. Understanding these dynamics facilitates quality control, targeted starter design and sustainable production, with wider implications for complex fermentations in food and biotechnology.

Research from Nature Portfolio

Recent exploration of environmental microbial inputs has illuminated their role in light-flavour Baijiu. Systematic surveys demonstrated that key ester-forming Lactobacillus species, particularly L. acetotolerans, are sourced from air and jar surfaces, with seasonal fluctuations affecting their initial abundance and the subsequent pace of ester formation. By integrating volatile profiling with multivariate analysis, researchers linked environmental reservoirs to late-stage flavour consistency. Another study characterised microbial communities in major liquor starters under high-temperature conditions. Pyrosequencing revealed over 300 bacterial and 70 fungal genera in Jiang- and Nong-flavour starters, with peak diversity at thermophilic stages. Network and predictive functional analyses identified core thermophilic taxa contributing to carbohydrate and amino acid metabolism. These findings provide a framework for isolating novel enzymes and optimising starter formulations for robust fermentation performance.

Microbial Ecology of Traditional Chinese Liquor Fermentation publication trend

The graph below shows the total number of articles in microbial ecology of traditional chinese liquor fermentation across all publications each year (not limited to Nature Index journals).

Technical terms

Solid-state fermentation: A process in which microorganisms grow on moist solid substrates without free liquid, common in traditional liquor production.

Daqu: A complex, thermophilic starter culture made from cereals, containing diverse microbes that saccharify starches and initiate fermentation.

Pit mud: Fermentation pit lining enriched with an anaerobic microbiome, notably Clostridia, responsible for caproic acid and flavour compound synthesis.

Metatranscriptomics: The study of collective microbial RNA transcripts to reveal active gene expression and metabolic pathways in situ.

Core microbiota: A subset of microbial taxa that consistently occur and perform essential functions throughout a fermentation process.

Microbial succession: Sequential changes in community composition over time, driven by environmental conditions and metabolic interactions.

References

1. Unraveling Core Functional Microbiota in Traditional Solid-State Fermentation by High-Throughput Amplicons and Metatranscriptomics Sequencing. Frontiers in Microbiology (2017).
2. Diversity and Function of Microbial Community in Chinese Strong-Flavor Baijiu Ecosystem: A Review. Frontiers in Microbiology (2018).
3. Effect of the environment microbiota on the flavour of light-flavour Baijiu during spontaneous fermentation. Scientific Reports (2018).
4. Deciphering the Composition and Functional Profile of the Microbial Communities in Chinese Moutai Liquor Starters. Frontiers in Microbiology (2019).
5. The functional potential and active populations of the pit mud microbiome for the production of Chinese strong‐flavour liquor. Microbial Biotechnology (2017).
6. New microbial resource: microbial diversity, function and dynamics in Chinese liquor starter. Scientific Reports (2017).