• 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.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1061-1070
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• 2019

In the present study, the optimization of poly(${\gamma}$-glutamic acid) (${\gamma}$-PGA) production by Bacillus sp. FBL-2 was studied using a statistical approach. One-factor-at-a-time method was used to investigate the effect of carbon sources and nitrogen sources on ${\gamma}$-PGA production and was utilized to select the most significant nutrients affecting the yield of ${\gamma}$-PGA. After identifying effective nutrients, response surface methodology with central composite design (CCD) was used to obtain a mathematical model to identify the optimum concentrations of the key nutrients (sucrose, $\text\tiny{L}$-glutamic acid, yeast extract, and citric acid) for improvement of ${\gamma}$-PGA production. The optimum amount of significant medium components appeared to be sucrose 51.73 g/l, $\text\tiny{L}$-glutamic acid 105.30 g/l, yeast extract 13.25 g/l, and citric acid 10.04 g/l. The optimized medium was validated experimentally, and ${\gamma}$-PGA production increased significantly from 3.59 g/l (0.33 g/l/h) to 44.04 g/l (3.67 g/l/h) when strain FBL-2 was cultivated under the optimal medium developed by the statistical approach, as compared to non-optimized medium.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.9
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• pp.1114-1121
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• 2017

Bacillus strains not producing harmful components were isolated from Korean traditional soybean products. Extracellular enzyme activities (amylase, protease, cellulase, and xylanase) of isolated Bacillus strains were measured, and Bacillus strains with high protease activity were selected. The selected 15 strains were identified as Bacillus amyloliquefaciens (10), Bacillus methylotrophicus (1), Bacillus velezensis (1), and Bacillus subtilis (3). Among them, B. subtilis JBG17019, B. amyloliquefaciens JBD17076, and B. amyloliquefaciens JBD17109 showed antimicrobial activities against food-borne microorganisms. The production abilities of glutamate, glutamine, and poly-${\gamma}$-glutamic acid (${\gamma}$-PGA) of the selected Bacillus strains were measured to analyze fermentation characteristics related to glutamic acid metabolism. The factor for multivariate was analyzed by the principal components analysis (PCA) method between fermentation characteristics and ${\gamma}$-PGA production. The three principal components were classified according to the PCA method: PC1 [enzyme activity (amylase, cellulase, and xylanase)], PC2 (${\gamma}$-PGA), and PC3 (protease, glutamate, and glutamine). As a result, B. amyloliquefaciens JBD17076 and B. subtilis JBG17019 strains were evaluated as having excellent enzyme activity and ${\gamma}$-PGA production.

• Nutrition Research and Practice
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• v.15 no.3
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• pp.309-318
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• 2021

BACKGROUD/OBJECTIVES: Data regarding the effects of poly-γ-glutamic acid (γ-PGA) on sleep status are limited. This study aimed to test whether γ-PGA and vitamin B₆ (VitB6) supplements improve sleep duration and quality. SUBJECTS/METHODS: A factorial randomized, double-blinded, placebo-controlled crossover study included 47 adults (25 men and 22 women) who were free of chronic disease. Stratified randomized allocation considered age and gender for three interventions, group A (supplementation with γ-PGA 600 mg; n = 16), group B (supplementation with VitB6 100 mg; n = 14), and group C (dual supplementation of both γ-PGA 600 mg and VitB6 100 mg; n = 17). Participants underwent a 1-mon intervention period, followed by a 1-mon washout period, and then a second 1-mon intervention period. Differences (mean ± SD) in nighttime sleep status before and after supplementation were compared between the placebo and intervention groups using nonparametric tests. RESULTS: Significant changes in sleep duration (0.27 ± 0.98 h, P < 0.05) and the Pittsburgh Sleep Quality Index global score (-0.52 ± 1.58, P < 0.05) indicating improved sleep status were observed in the intervention compared with the placebo of group C while no significant changes were observed in groups A and B. No statistical significance was detected between the intervention and the placebo; however, there was a greater increase in the group C intervention (4.59 ± 38.5 ng/mL) in serum serotonin concentrations than the groups A and B interventions. No side effects were observed. CONCLUSIONS: On the basis of these findings, the dual supplementation of γ-PGA and VitB6 may be effective as functional food components to improve nighttime sleep status.

• Journal of Microbiology and Biotechnology
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• v.27 no.5
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• pp.1032-1037
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• 2017

The poly-${\gamma}$-$\small{D}$-glutamic acid (PGA) capsule, a major virulence factor of Bacillus anthracis, provides protection of the bacterium from phagocytosis and allows its unimpeded growth in the host. We investigated crosstalk between murine natural killer (NK) cells and macrophages stimulated with the PGA capsule of Bacillus licheniformis, a surrogate of the B. anthracis capsule. PGA induced interferon-gamma production from NK cells cultured with macrophages. This effect was dependent on macrophage-derived IL-12 and cell-cell contact interaction with macrophages through NK cell receptor NKG2D and its ligand RAE-1. The results showed that PGA could enhance NK cell activation by inducing IL-12 production in macrophages and a contact-dependent crosstalk with macrophages.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.35-41
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• 2014

Poly(g-glutamic acid) (g-PGA) is a very promising biodegradable polymer that is produced by microorganism of Bacillus subtilis. Because g-PGA is water-soluble, anionic, biodegradable, and even edible, its potential applications have been studied from an industrial standpoint. In this study, we fabricated porous g-PGA foams by means of a freeze-solvent extraction method for tissue-engineering applications. Porous g-PGA foams were chemically cross-linked using a hexamethylene diisocyanate solution. An aqueous basic solution was used to neutralize g-PGA foam for cell culturing. During an in vitro cell culture study, it was observed that primary rabbit ear chondrocytes were well at tached and spread over the surface oft hree-dimensional cross-linkedg-PGA foam. From these results, it is concluded that cross-linkedg-PGA foam is aprom is in gmaterial for tissue-engineering applications, especially those pertaining to the regeneration of human cartilage.

• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.354-361
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• 2008

A novel bacterium isolated from Cheonggukjang was identified as a glutamate-dependent Bacillus subtilis HA with 98.3% similarity to Bacillus subtilis Z99104. Optimization of poly-$\gamma$-glutamic acid ($\gamma$-PGA) production by modulating fermentation factors including carbon sources, nitrogen sources, inorganic salts and fermentation time was investigated. Optimum culture broth for $\gamma$-PGA production consisted of 3% glutamate, 3% glucose and various salts, resulting in the PGA production of 22.5 g/L by shaking culture for 72 hr at $37^{\circ}C$. Average molecular weight of $\gamma$-PGA was determined to be 1,220 kDa through MALLS analysis. The $\gamma$-PGA solution showed a typical pseudoplastic flow behavior, and a great decrease in consistency below pH 6.0 regardless of the same molecular weight of $\gamma$-PGA. The molecular weights of isolated $\gamma$-PGA were drastically decreased by heat treatment in various acidic conditions, resulting in different hydrolysis of $\gamma$-PGA. The consistency of $\gamma$-PGA solution was greatly decreased with increase heating time in acidic conditions.

• Journal of Microbiology and Biotechnology
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• v.34 no.3
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• pp.735-745
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• 2024

Avian influenza is a serious threat to both public health and the poultry industry worldwide. This respiratory virus can be combated by eliciting robust immune responses at the site of infection through mucosal immunization. Recombinant probiotics, specifically lactic acid bacteria, are safe and effective carriers for mucosal vaccines. In this study, we engineered recombinant fusion protein by fusing the hemagglutinin 1 (HA1) subunit of the A/Aquatic bird/Korea/W81/2005 (H5N2) with the Bacillus subtilis poly γ-glutamic acid synthetase A (pgsA) at the surface of Lactobacillus casei (pgsA-HA1/L. casei). Using subcellular fractionation and flow cytometry we confirmed the surface localization of this fusion protein. Mucosal administration of pgsA-HA1/L. casei in mice resulted in significant levels of HA1-specific serum IgG, mucosal IgA and neutralizing antibodies against the H5N2 virus. Additionally, pgsA-HA1/L. casei-induced systemic and local cell-mediated immune responses specific to HA1, as evidenced by an increased number of IFN-γ and IL-4 secreting cells in the spleens and higher levels of IL-4 in the local lymphocyte supernatants. Finally, mice inoculated with pgsA-HA1/L. casei were protected against a 10LD50 dose of the homologous mouse-adapted H5N2 virus. These results suggest that mucosal immunization with L. casei displaying HA1 on its surface could be a potential strategy for developing a mucosal vaccine against other H5 subtype viruses.

• Food Science and Preservation
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• v.31 no.1
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• pp.138-148
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• 2024

The production of poly-γ-glutamic acid (γ-PGA) and γ-aminobutyric acid (GABA) was optimized by serial fermentation of Dendropanax morbiferus extract (DME) using Bacillus subtilis HA and Lactobacillus plantarum KS2020. The 1st alkaline fermentation was performed on 60% DME including 2% glucose and 10% monosodium ʟ-glutamate (MSG) as a precursor. The 1^st fermented DME had 57 mg% tyrosine. Consequently, the 2^nd lactic acid fermentation for 5 days increased the tyrosine content of 106 mg%. The mucilage containing γ-PGA showed a high content of 3.50% on the first day of alkaline fermentation and then increased to 4.10% after 2 days. The precursor (MSG) remaining in the 1^st fermented DME was efficiently converted to GABA by the 2^nd lactic acid fermentation in the presence of 5% skim milk, 1.5% glucose and 0.5% yeast extract, resulting in the production of 18.29 mg/mL GABA. The viable cells of lactic acid bacteria increased and indicated 9.49 log CFU/mL on the fermentation for 5 days, and the acidity of co-fermented DME indicated the highest value of 1.55%. Conclusively, the serial fermented DME has multi-functional ingredients containing γ-PGA, GABA, peptides and probiotics.

• Journal of Life Science
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• v.16 no.2 s.75
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• pp.175-179
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• 2006

A bacterium that produced a large amount of poly-$\gamma$-glutamate (PGA) was isolated from the compost and designated as Bacillus subtilis CH-10. The optimum temperature and pH for PGA production were at $37^{\circ}C$ and 7.5, respectively. The maximum amount of PGA production (18.84 mg/ml) was obtained when it was grown in a medium containing 3% L-glutamate and 5% sucrose at $37^{\circ}C$ with shaking. The result that the L-glutamate significantly induced PGA production indicates that it produces a PGA by the glutamate dependent manner. Some properties of the PGA obtained at different times of cultivation were investigated by SDS-PAGE and ninhydrin analysis. The PGA production was elongated along with cultivation time and maximum amount was achieved at 96 h. Average molecular weight of PGA was estimated to be 1100 kDa by FDNB method.