Oxygen influences spatial heterogeneity and microbial succession dynamics during Baijiu stacking process

Area of Science:

• Microbiology
• Fermentation Science
• Environmental Biotechnology

Background:

• Spontaneous solid-state stacking process (SSSP) is crucial for Baijiu fermentation.
• Understanding microbial assembly and spatial heterogeneity is key to optimizing fermentation efficiency.
• Environmental microorganisms are enriched and assembled during SSSP.

Purpose of the Study:

• To investigate how SSSP creates spatial heterogeneity within stacking piles.
• To identify the microbial dynamics and environmental factors driving this heterogeneity.
• To understand the role of oxygen gradients and dominant microbial species in shaping the SSSP microbiome.

Main Methods:

• Spatiotemporal sampling of stacking piles.
• Analysis of oxygen concentration gradients to define distinct layers (depleted, transitional, enriched).
• Microbial community analysis, focusing on dominant species and their metabolic roles (e.g., poxL, catE gene expression).

Main Results:

• SSSP establishes distinct oxygen-defined layers based on oxygen exchange difficulty.
• Microbial succession rates vary significantly across these layers (V_depleted > V_transitional > V_enriched), accelerating spatial heterogeneity.
• Acetilactobacillus jinshanensis dominates low-oxygen layers, actively reducing oxygen disturbance and sustaining heterogeneity.

Conclusions:

• Oxygen control is a critical factor in shaping spatial heterogeneity during SSSP.
• This heterogeneity leads to the development of specific functional microbiomes.
• Implementing spatial heterogeneity management can enable precise control over solid-state fermentation systems.