Jung Woo Yong, Jung Ji Young, Lee Hyo Jung, Jeon Che Ok
Department of Life Science, Chung-Ang University Seoul, South Korea.
Front Microbiol. 2016 May 31;7:827. doi: 10.3389/fmicb.2016.00827. eCollection 2016.
Doenjang 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 doenjang. Viable bacterial cells were approximately three orders of magnitude higher than fungal cells, suggesting that bacteria are more responsible for doenjang 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 doenjang samples included Bacillus, Enterococcus, Lactobacillus, Clostridium, Staphylococcus, Corynebacterium, Oceanobacillus, and Tetragenococcus. These genera were found either in doenjang-meju or solar salts, but not in both, suggesting two separate sources of bacteria. Bacillus and Enterococcus were dominant genera during the fermentation, but their abundances were not associated with metabolite changes, suggesting that they may not be major players in doenjang fermentation. Tetragenococcus was dominant in 108 day-doenjang samples, when lactate, acetate, putrescine, and tyramine increased quickly as glucose and fructose decreased, indicating that Tetragenococcus might be primarily responsible for organic acid and biogenic amine production. Lactobacillus 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 doenjang fermentation process, contributing to the production of safe and high-quality doenjang.
将大酱样品一式三份制备，并分析其在整个发酵过程中的微生物丰度、细菌群落和代谢产物，以研究大酱中微生物的功能特性。活细菌细胞比真菌细胞大约高三个数量级，这表明细菌对大酱发酵的作用更大。焦磷酸测序和质子核磁共振光谱分别用于分析细菌群落和代谢产物。基于16S rRNA基因序列的细菌群落分析表明，大酱样品中包括芽孢杆菌属、肠球菌属、乳杆菌属、梭菌属、葡萄球菌属、棒状杆菌属、嗜盐芽孢杆菌属和四联球菌属。这些属要么在大酱曲中发现，要么在日晒盐中发现，但不会同时在两者中出现，这表明细菌有两个独立的来源。芽孢杆菌属和肠球菌属在发酵过程中是优势属，但它们的丰度与代谢产物变化无关，这表明它们可能不是大酱发酵的主要参与者。四联球菌属在108天大酱样品中占主导地位，此时随着葡萄糖和果糖的减少，乳酸、乙酸、腐胺和酪胺迅速增加，这表明四联球菌属可能主要负责有机酸和生物胺的产生。乳杆菌属从179天的样品中被鉴定为优势菌群，与γ-氨基丁酸（GABA）的增加和半乳糖的减少有关，这表明该属在发酵过程中作为主要GABA生产者的潜在作用。本研究结果阐明了大酱发酵过程中主要细菌群落的功能特性，有助于生产安全、高质量的大酱。
