Microbial communities in the fermentation of , a Korean traditional soybean brick.

is a traditional Korean soybean brick characterized by diverse microbial communities. The microbial communities in were identified at the phylum and genus levels using high-throughput sequencing. During fermentation, diverse factors such as total bacterial cell numbers, moisture content, salinity, pH, enzyme activities, and free amino acids were monitored. After 30 days of fermentation, microbial adaptation and increased protease activity resulted in significant changes, including an increase in pH and alterations in free amino acid content by day 70. Bacterial community analysis revealed significant changes in , , and levels as fermentation progressed. The decrease in pH during fermentation was influenced by lactic acid bacteria, which affected bacterial dynamics. At the end of fermentation, the fungal community was dominated by , , and , which affected the free amino acid levels. These results indicate that pH and moisture content may be significant factors in determining microbial communities.