AUTHOR=Jung Woo Yong , Jung Ji Young , Lee Hyo Jung , Jeon Che Ok 

TITLE=Functional Characterization of Bacterial Communities Responsible for Fermentation of Doenjang: A Traditional Korean Fermented Soybean Paste

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.00827

DOI=10.3389/fmicb.2016.00827

ISSN=1664-302X

ABSTRACT=<p><italic>Doenjang</italic> samples were prepared in triplicate and their microbial abundance, bacterial communities, and metabolites throughout fermentation were analyzed to investigate the functional properties of microorganisms in <italic>doenjang</italic>. Viable bacterial cells were approximately three orders of magnitude higher than fungal cells, suggesting that bacteria are more responsible for <italic>doenjang</italic> fermentation. Pyrosequencing and proton nuclear magnetic resonance spectroscopy were applied for the analysis of bacterial communities and metabolites, respectively. Bacterial community analysis based on 16S rRNA gene sequences revealed that <italic>doenjang</italic> samples included <italic>Bacillus, Enterococcus, Lactobacillus, Clostridium, Staphylococcus, Corynebacterium, Oceanobacillus</italic>, and <italic>Tetragenococcus</italic>. These genera were found either in <italic>doenjang</italic>-<italic>meju</italic> or solar salts, but not in both, suggesting two separate sources of bacteria. <italic>Bacillus</italic> and <italic>Enterococcus</italic> were dominant genera during the fermentation, but their abundances were not associated with metabolite changes, suggesting that they may not be major players in <italic>doenjang</italic> fermentation. <italic>Tetragenococcus</italic> was dominant in 108 day-<italic>doenjang</italic> samples, when lactate, acetate, putrescine, and tyramine increased quickly as glucose and fructose decreased, indicating that <italic>Tetragenococcus</italic> might be primarily responsible for organic acid and biogenic amine production. <italic>Lactobacillus</italic> was identified as a dominant group from the 179-day samples, associated with the increase of γ-aminobutyric acid (GABA) and the decrease of galactose, indicating a potential role for this genus as a major GABA producer during fermentation. The results of this study clarified the functional properties of major bacterial communities in the <italic>doenjang</italic> fermentation process, contributing to the production of safe and high-quality <italic>doenjang</italic>.</p>