• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.324-332
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• 2016

A bacterial strain capable of hydrolyzing xylan was isolated from fermented soybean paste obtained from a domestic Buddhist temple, using enrichment culture with rice straw as a carbon source. The isolate, named YB-1301, was identified as Bacillus safensis on the basis of its DNA gyrase subunit B gene (gyrB) sequence. The xylanase productivity of strain YB-1301 was drastically increased when it was grown in the presence of wheat bran or various xylans. In particular, the maximum xylanase productivity reached above 340 U/ml in the culture filtrate from LB broth supplemented with only birchwood xylan at shake-flask level. The xylanase production was significantly induced by xylans at the stationary growth phase in LB medium containing xylan, whereas only a small amount of xylanase was constitutively produced from cells grown in LB medium with no addition of xylan. Furthermore, xylanase biosynthesis was induced more rapidly by the enzymatically hydrolyzed products of xylan than by the non-hydrolyzed xylan. In addition, the xylanase in the culture filtrate of B. safensis YB-1301 was found to have optimal activity at 55℃ and pH 6.5–7.0.

• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1081-1087
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• 2014

Aspergillus oryzae is generally recognized as safe, but it is closely related to A. flavus in morphology and genetic characteristics. In this study, we tested the aflatoxigenicity and genetic analysis of nine commercial A. oryzae strains that were used in Korean soybean fermented products. Cultural and HPLC analyses showed that none of the commercial strains produced detectable amount of aflatoxins. According to the molecular analysis of 17 genes in the aflatoxin (AF) biosynthetic pathway, the commercial strains could be classified into three groups. The group I strains contained all the 17 AF biosynthetic genes tested in this study; the group II strains deleted nine AF biosynthetic genes and possessed eight genes, including aflG, aflI, aflK, aflL, aflM, aflO, aflP, and aflQ; the group III strains only had six AF biosynthetic genes, including aflG, aflI, aflK, aflO, aflP, and aflQ. With the reverse transcription polymerase chain reaction, the group I A. oryzae strains showed no expression of aflG, aflQ and/or aflM genes, which resulted in the lack of AF-producing ability. Group II and group III strains could not produce AF owing to the deletion of more than half of the AF biosynthetic genes. In addition, the sequence data of polyketide synthase A (pksA) of group I strains of A. oryzae showed that there were three point mutations (two silent mutations and one missense mutation) compared with aflatoxigenic A. flavus used as the positive control in this study.

• Nutrition Research and Practice
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• v.9 no.6
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• pp.569-578
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• 2015

BACKGROUND/OBJECTIVES: Fermentation can increase functional compounds in fermented soybean products, thereby improving antioxidant and/or anti-inflammatory activities. We investigated the changes in the contents of phenolics and isoflavones, antioxidant activity and anti-inflammatory activity of Doenjang during fermentation and aging. MATERIALS/METHODS: Doenjang was made by inoculating Aspergillus oryzae and Bacillus licheniformis in soybeans, fermenting and aging for 1, 3, 6, 8, and 12 months (D1, D3, D6, D8, and D12). Doenjang was extracted using ethanol, and sequentially fractioned by hexane, dichloromethane (DM), ethylacetate (EA), n-butanol, and water. The contents of total phenolics, flavonoids and isoflavones, 2,2-diphenyl-1 picryl hydrazyl (DPPH) radical scavenging activity, and ferric reducing antioxidant power (FRAP) were measured. Anti-inflammatory effects in terms of nitric oxide (NO), prostaglandin (PG) E2 and pro-inflammatory cytokine production and inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 expressions were also measured using LPS-treated RAW 264.7 macrophages. RESULTS: Total phenolic and flavonoid contents showed a gradual increase during fermentation and 6 months of aging and were sustained thereafter. DPPH radical scavenging activity and FRAP were increased by fermentation. FRAP was further increased by aging, but DPPH radical scavenging activity was not. Total isoflavone and glycoside contents decreased during fermentation and the aging process, while aglycone content and its proportion increased up to 3 or 6 months of aging and then showed a slow decrease. DM and EA fractions of Doenjang showed much higher total phenolic and flavonoid contents, and DPPH radical scavenging activity than the others. At $100{\mu}g/mL$, DM and EA fractions of D12 showed strongly suppressed NO production to 55.6% and 52.5% of control, respectively, and PGE2 production to 25.0% and 28.3% of control with inhibition of iNOS or COX-2 protein expression in macrophages. CONCLUSIONS: Twelve month-aged Doenjang has potent antioxidant and anti-inflammatory activities with high levels of phenolics and isoflavone aglycones, and can be used as a beneficial food for human health.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.339-346
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• 2014

A bacterial strain was isolated from homemade doenjang (Korean fermented soybean paste) as a producer of the extracellular ${\beta}$-galactosidase, capable of hydrolyzing lactose to liberate galactose and glucose residues. The isolate YB-1414 has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. The production of ${\beta}$-galactosidase by B. licheniformis YB-1414 reached maximum levels of 6.2 U/ml in culture medium containing wheat bran (1%) and yeast extract (2.5%) as carbon and nitrogen sources, respectively. Particularly, the insoluble fraction was more effective for ${\beta}$-galactosidase production than the soluble extract of wheat bran. The enzyme exhibited maximum activity for hydrolysis of para-nitrophenyl-${\beta}$-D-galactopyranoside (pNP-${\beta}Gal$) under reaction conditions of pH 6.0 and $55-60^{\circ}C$. Its hydrolyzing activity for pNP-${\beta}Gal$ was drastically decreased by the addition of low concentrations of galactose, but only slightly decreased by glucose, with 85% of maximal activity in the presence of 400 mM glucose.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.594-599
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• 2001

This study was attempted to isolate and identify the strain revealing high angiotensin converting enzyme (ACE) inhibitory activity from various soy fermented foods, i.e. meju, soybean paste and soy sauce. Forty-two strains with morphologically different characteristics were selected and the ACE inhibitory and proteolytic activities were examined. Of the strains tested, SS103 which was isolated from soy sauce showed the highest ACE inhibitory and proteolytic activities and was finally selected for further studies. The SS103 strain showed motility, rod form and ellipsoidal spores. The shape of colonies on the agar media was irregular, mucoidal and surface dull. The strain could grow under aerobic conditions of pH 5~9 and 10~$50^{\circ}C$. Main cellular fatty acid was $C_{15:0}$ anteiso, $C_{17:0}$ cis and $C_{17:0}$ iso, which was 33.9%, 18.8% and 16.5%, respectively. Based upon these morphological, biochemical and cultural properties, SS103 was identified as a Bacillus subtilis. Optimum cultural condition of Bacillus subtilis SS103 was pH 8.0, $37^{\circ}C$ and 48 hr.48 hr.

• Food Science and Preservation
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• v.15 no.1
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• pp.139-143
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• 2008

The potential use of Doenjang in place of salted-fish juice as an ingredient in Kimchi fermentation was examined, to improve Kimchi qualities such as flavor and taste. Quality characteristics were monitored during progressive fermentation of Kimchi with Doenjang (KD) at 7 d intervals for 28d at constant temperature $(10^{\circ}C)$. The data showed that the pH of KD was somewhat lower than that of the control as fermentation progressed. The titratable acidity in KD was linearly proportional to the pH change. Both the growth of lactic acid bacilli and total bacteria in Kimchi were inhibited in KD compared to control. In terms of color, the L, a, and b values of KD were all lower than those of control. In sensory evaluation, the taste, flavor, color, and overall acceptability of the new form of Kimchi were increased significantly by addition of 5 % (w/w) Doenjang (p<0.05). All data indicated that the color and taste properties of KD were improved by addition of Doenjang during fermentation.

• Nutrition Research and Practice
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• v.18 no.5
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• pp.663-673
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• 2024

BACKGROUND/OBJECTIVES: Poly-γ-glutamic acid (γ-PGA), a natural polymer found in fermented soybean products, has been reported to play a prebiotic role in the gut. This intervention study investigated the effects of γ-PGA-containing supplement consumption on urinary microbiota in healthy adults because of limited data on such investigation. SUBJECTS/METHODS: A 4-week parallel trial including 39 male and female Korean adults, who were free of chronic diseases and infection, was designed as a randomized, double-blinded, placebo-controlled study. A total of 30 participants completed the study wherein the intervention group (n = 17) received a mixture supplement containing 600 mg/day of γ-PGA and 100 mg/day of vitamin B6, while the control group (n = 13) received a placebo. Paired datasets (baseline and endpoint data) of microbiota profiles, which were constructed via urinary assays of microbe-derived extracellular vesicles, were analyzed and compared between the two groups. RESULTS: Only the intervention group yielded significant results for the Bray-Curtis and Jaccard dissimilarity indices between baseline and endpoint data (P < 0.05). In the phylum-level analysis of microbial composition, the Firmicutes to Bacteroidetes ratio (FB ratio) tended to decrease from baseline in the intervention group; however, it increased in the control group. Differences between the baseline and endpoint FB ratios were significant between the two groups (P < 0.05). CONCLUSION: This study's findings suggest that γ-PGA-vitamin B6 supplementation potentially alters the microbial community composition of a host. Further investigation into the biological consequences of commensal microbiota alteration by γ-PGA-containing supplement consumption is warranted.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.419-426
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• 2015

The aims of this study were to isolate spore-forming Bacillus strains that exhibit high digestibility and anti-pathogenic bacteria toward feed for calves. Total 136 spore-forming strains were isolated from finished feeds and their ingredients. Among them, 93 strains were identified as Bacillus species when analyzed by 16S rRNA sequencing. For industrial use, three strains named as Bacillus licheniformis SHS14, B. subtilis LCB7, B. amyloliquefaciens LCB10 were selected after evaluating the industrial standards that are related with heat and acid resistance, enzyme activities, and anti-pathogenic activities against Samonella dublin ATCC15480 and E. coli K99. After each culture, 3 selected strains were mixed together at 1:1:1 (v/v/v) ratio and then prepared as the mixed starter culture for feeding. The changes in microbial community were analyzed via 16S rRNA metagenomics. The initial community ratio among three strains was maintained even after manufacturing into final products. Also, in vitro, enzymatic and anti-pathogenic activities were almost same as those when cultured in single culture, and results of anti-pathogenic activities conducted with calves showed 90% activities against lincomycin, which would be indicative of a promising feed starter.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.77-82
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• 2011

This study was conducted to provide information for improving the quality characteristics of Buckwheat Soksungjang (BWS). We determined aminotype nitrogen content, total microbial flora counts, the population of Bacillus cereus, presence of volatile compounds, fibrinolytic activity, antioxidant activity, ACE inhibition rate, and a sensory evaluation. The aminotype nitrogen increased gradually during fermentation. We found a decreasing population of B. cereus during fermentation, thus, the edible period for BWS was more than 30 days after fermentation. Acetaldehyde, butanol, and pyrazine were detected as volatile compounds after fermentation. The fibrinolytic activities of a 10% BWS water extract were high at 120.8 units compared to the control (71.6 units). In a sensory evaluation, Soksungjang with 60% added BW showed a significantly higher score (p < 0.001) for color, taste, smell, texture, and overall. The results suggest that a new type of shortened fermented soybean paste had good safety, bioactivities, and sensory characteristics within 4 weeks.

• Food Science and Preservation
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• v.13 no.4
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• pp.483-489
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• 2006

Considering the development of fusion ingredients rom red ginseng and Cheonggukjang (soybean-fermented food), their commercial powders were evaluated in their Hunter's colors, volatile compounds, and sensory properties depending on manufacturing companies and mixing ratio of both powdered products. Hunters L, a and b values of red ginseng powders were $75.56\sim85.50,\;1.90\sim6.30,\;and\;23.29\sim35.08$, respectively, while those of Cheonggukjang powders were $64.96\sim71.69,\;4.64\sim8.30,\;and\;30.45\sim36.50$, respectively. Volatile compounds were mainly composed of hexanal, $\beta-pinene$, methyl benzene, 3,5-methyl propyl nonane, 2-propanone, decane, and 2,8-dimethyl undecane in red ginseng samples, and of 2,3-butanedione, decane, 2,2,7,7-tetramethyl octane, and 3-methyl butanal in Cheonggukjang samples. Total volatiles of the mixed samples decreased as ginseng decreased and Cheonggukjang increased. The mixed sample of both red ginseng and cheonggukjang in same amounts was the highest in its sensory acceptability, which was composed in the order of 2-propanone, 2-butanone, pentane, hexanal and 3-methyl butanal. The above results indicate that red ginseng and Cheonggukjang showed a potential as fusion ingredient for preparing new functional produce through further processing.