Thermal-driven microbial succession and biochemical maturation during traditional wheat nuruk fermentation
This study investigated microbial succession, enzymatic activities, and metabolite dynamics during the traditional manufacturing process of Korean wheat-based nuruk using metagenomic and biochemical analyses. Nuruk was produced through a standardized six-step fermentation process including a high-temperature fermentation stage at 45 °C. Amplicon sequencing targeting bacterial 16S rRNA and fungal ITS regions was performed to evaluate microbial community dynamics across the manufacturing stages. Simultaneously, biochemical characteristics including a-amylase activity, protease activity, ß-glucosidase activity, free amino acid composition, and soluble sugar profiles were analyzed. The high-temperature fermentation stage induced major ecological and biochemical transitions, including selective enrichment of thermotolerant fungal taxa such as Saccharomycopsis and Lichtheimia, accompanied by sharp increases in enzymatic activities, proline accumulation, and soluble sugar production. Correlation analysis, redundancy analysis, and microbial co-occurrence network analysis revealed strong associations between microbial succession and biochemical maturation during fermentation. The results suggest that thermal and desiccation stresses function as major selective pressures shaping cooperative microbial interactions and quality formation in traditional nuruk fermentation ecosystems.
This study investigated microbial succession, enzymatic activities, and metabolite dynamics during the traditional manufacturing process of Korean wheat-based nuruk using metagenomic and biochemical analyses. Nuruk was produced through a standardized six-step fermentation process including a high-temperature fermentation stage at 45 °C. Amplicon sequencing targeting bacterial 16S rRNA and fungal ITS regions was performed to evaluate microbial community dynamics across the manufacturing stages. Simultaneously, biochemical characteristics including a-amylase activity, protease activity, ß-glucosidase activity, free amino acid composition, and soluble sugar profiles were analyzed. The high-temperature fermentation stage induced major ecological and biochemical transitions, including selective enrichment of thermotolerant fungal taxa such as Saccharomycopsis and Lichtheimia, accompanied by sharp increases in enzymatic activities, proline accumulation, and soluble sugar production. Correlation analysis, redundancy analysis, and microbial co-occurrence network analysis revealed strong associations between microbial succession and biochemical maturation during fermentation. The results suggest that thermal and desiccation stresses function as major selective pressures shaping cooperative microbial interactions and quality formation in traditional nuruk fermentation ecosystems.
Jeonbuk National University