# Temporal heterogeneity of microbial ecosystems and its formation mechanisms in Moutai-flavor Baijiu fermentation

## TL;DR

This study explores how microbial ecosystems in Moutai-flavor Baijiu fermentation change over time and identifies factors influencing these changes.

## Contribution

The study identifies cooling yard surface basicity as a key driver of microbial community shifts in aging workshops.

## Key findings

- Lactobacillus increased from 15.02% to 35.59% in fermented grains as workshops aged from 5 to 30 years.
- Cooling yards contributed 54.2% of microbes in fermented grains on average.
- Alkalotolerant bacteria like Alkalibacterium and Nesterenkonia thrived in low basicity cooling yards.

## Abstract

The influence of workshop age on Moutai-flavor Baijiu fermentation is recognized, but the mechanisms driving microbial community shifts remain unclear. Understanding how the physical environment selects for specific microbiota is crucial for optimizing new workshops. Through 16S/ITS sequencing of pit-entry fermented grains, Daqu, air, and cooling yards in 5-, 10-, 20-, and 30-year-old workshops, Lactobacillus emerged as a key discriminant genus, increasing from 15.02% (5-year) to 35.59% (30-year). SourceTracker analysis revealed the cooling yard as the primary microbial source, contributing 54.2% on average to fermented grains. CO2-TPD analysis showed a 3.6-fold reduction in cooling yard surface basicity (from 0.11 to 0.03 mmol·g−1) over 30 years, resulting in high abundances (>10%) of alkalotolerant bacteria (e.g., Alkalibacterium, Nesterenkonia) and low Lactobacillus (2.17%). Nesterenkonia was also a biomarker in 5-year fermented grains. This confirms cooling yard surface basicity drives microecological differences, revealing how long-term production practices domesticate microbial communities and providing a theoretical basis for new workshop adaptation.