Project description:Soybean paste (Doujiang) is one of the traditional fermented foods from China, fermented by various microorganisms. However, the microflora of Doujiang keeps little known. In this study, the microbial communities of seven kinds of representative Doujiang samples were investigated by both culture-independent and culture-dependent methods. We found that core OTUs among seven Doujiang samples were mainly from Bacillus, Pseudomonas, Candida, and Aspergillus according to Illumina sequencing. Every type of Doujiang sample harbored a different composition of microbial community. Doujiang LSJ and LBJ had the highest bacterial and fungal richness and diversity, respectively. The structure of microbial community was remarkably correlated with Doujiang properties-pH, and the content of total protein, soluble protein, amino acid, and total sugar (p < .05). Bacillus spp. were most frequently isolated bacterial species. Fungi of Monascus, Candida, and Aspergillus were also isolated. Eleven microbial strains showed high protease activities to degrade corn proteins, which can form obvious transparent hydrolytic circles in corn gluten meal medium plates. Therefore, microbial communities were supposed to tightly connect to Doujiang type and properties. It is possible to apply potential protein-degrading microbial strains to corn byproducts for protein production in the future study.
Project description:Three different forms of garlic, namely, fresh garlic (2%, 6%, 10%), heat-dried (1%, 2%, 3%) and freeze-dried (1%, 2%, 3%), were supplemented in soybean paste to prepare Doenjang and further evaluated for functional, nutritional and safety aspects. Results showed a considerable antioxidant and anti-proliferative activity of garlic-supplemented Doenjang. As a measure of nutritive value, a high amount of total free amino acids, 4,290.73 mg/100 g-5,492.94 mg/100 g, was observed in prepared Doenjang. Among all preparations, 3% freeze-dried garlic-supplemented Doenjang proved the most effective against gastric adenocarcinoma and lung adenocarcinoma with 50% inhibition concentration of 7.66 ± 0.53 mg/mL and 7.82 ± 0.34 mg/mL, respectively. However 10% fresh-garlicsupplemented Doenjang (GGD-10) showed better activity against colorectal adenocarcinoma (HT29) cell line. Furthermore, GGD-10 effectively reduced colony formation and altered mitochondrial membrane potential of HT29 cells. Absence of pathogenic bacteria (Staphylococcus aureus, Salmonella species and Bacillus cereus) and aflatoxin was observed in Doenjang samples. In addition, nontoxic amount of anti-nutritional biogenic amines was observed in all the samples. The results collectively suggest that the addition of garlic in Doenjang can improve its nutritional and functional value, resulting in the protection of consumers from protein deficiencies and various stress conditions.
Project description:This study compares the physicochemical properties, taste, and volatile compounds of Northeastern Chinese dajiang (C) and Korean doenjang (K) and distinguishes the discriminant volatile metabolites between them. The result revealed that compared to group C, group K exhibited more similar physicochemical properties and had lower pH, moisture, and amino acid nitrogen content, while demonstrating higher titratable acidity, salt content, and reduced sugar content. The electronic tongue analysis showed that the saltiness and umami of soybean pastes had high response values, enabling clear differentiation of the overall taste between the two types of soybean pastes. A total of 71 volatile substances from the soybean pastes were identified through solid-phase microextraction gas chromatography-mass spectrometry. Furthermore, orthogonal partial least squares discriminant analysis revealed 19 volatile compounds as differentially flavored metabolites. Our study provides a basis for explaining the differences in flavor difference of Northeastern Chinese dajiang and Korean doenjang from the perspective of volatile metabolites.
Project description: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.
Project description:Obesity is considered a risk factor for neurodegeneration. Because fermentation of soybean increases contents of various bioactive compounds with anti-obesity and anti-diabetic activities, we investigated the protective effect of doenjang, a Korean traditional fermented soybean paste, against neuroinflammation and neurodegeneration in the cortex and hippocampus of mice fed a high-fat (HF) diet. C57BL/6J mice were fed a low-fat diet, an HF diet, an HF-containing steamed soybean diet, or an HF-containing doenjang (DJ) diet for 11 weeks. Doenjang consumption alleviated hippocampal neuronal loss, which was increased by the HF diet. Accordingly, we observed higher cell proliferation and neurotrophic factor mRNA levels in the DJ group. Contents of oxidative metabolites and mRNA levels of oxidative stress- and neuroinflammation-related genes were lower in the DJ group compared to the HF group. Dietary doenjang reduced β-amyloid peptide (Aβ) levels by regulating gene expressions involved in Aβ production and degradation. Furthermore, doenjang consumption reduced tau hyperphosphorylation induced by HF feeding. Overall, doenjang was more effective than steamed soybean in suppressing neuroinflammation and neurodegeneration in mice fed an HF diet. These results suggest that bioactive compounds produced during the fermentation and aging of soybean may be involved in the enhanced neuroprotective effects of doenjang.
Project description:pin1 mutnat doesn't produce any floral organs, which can be rescued by exogenous application of IAA paste. Here we applied exogenous IAA paste and collected meristem tissue after different time points (30 min, 4hr, 12hr, 16hr). As a control we applied mock paste. Around 10 meristems were dissected under dissecting scope for each biological replicate. Some known IAA inducible genes were checked for their upregulation in extracted RNA, and there after the RNA was sequenced.
Project description:Consumption of soybean-based foods is affected by the flavor of the legume; due to the presence of undesirable compounds called "beany flavors". To solve this problem, the influence of solid state fermentation by lactobacilli on the production of volatile compounds in soybean paste was determined. The volatile's production was measured by gas chromatography. Forty compounds were identified in the different soybean pastes studied. The results showed that fermentation stimulates the production of desirable volatile compounds in foods such as ketones (22-75%) and decreased unpleasant compounds (10-84%).The consumers acceptance study showed that a group of participants (30% approximately) preferred the fermented samples associated with sweet and acid aroma like yogurt. In conclusion, the fermentation positively influences the generation of desirable volatile compounds and completely reduces hexanal in one sample. Therefore, fermentation with the studied strains is a valid strategy to modify the aroma profile of a soybean-based food matrix.Supplementary informationThe online version contains supplementary material available at 10.1007/s13197-021-05210-5.
Project description:Bacillus velezensis YJ11-1-4 is a strain that exhibits broad-spectrum antimicrobial activity against various pathogens. It was isolated from doenjang, a traditional Korean fermented soybean paste. The genome comprises a single circular chromosome of 4,006,637 bp with 46.42% G+C content without plasmids.