• KSBB Journal
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• v.27 no.2
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• pp.127-130
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• 2012

In this study, the effects of pH, temperature, IPTG concentration and substrate (MSG) concentration on gamma-aminobutyric acid (GABA) production in engineered Escherichia coli were investigated. Glutamate decarboxylase and glutamate/GABA antiporter were overexpressed in GABA aminotransferase knock-out strain for GABA production. The result of optimization study showed the GABA bioconversion was optimized at pH 3.5, $30^{\circ}C$, 0.5 mM IPTG, 10 g/L MSG. At this condition, 5.23 g/L of final GABA concentration of was achieved from 10 g/L of MSG, which corresponded to a GABA yield of 85.77%.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.315-319
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• 1992

Korean green tea leaves which were harvested three times(May, June, August) were treated with anaerobic conditions and were measured changes of ${\gamma}-aminobutyric$ acid(GABA) and other constituents. In anaerobically treated green tea leaves, the content of ${\gamma}-aminobutyric$ acid(GABA) and alanine increased while glutamic acid decreased. Whereas theanine, arginine, caffeine and tannin showed little change and the content of vitamine C slightly decreased with the passing of the anaerobic treatment time. Formation of GABA, a hypotensive constituents, was proportioned to the content of glutamic acid and the optimum time of the anaerobic treatment was about 12 hours. In the anaerobic treatment of green tea leaves, effect of nitrogen gas and vacuum condition was no difference between two.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.710-716
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• 2016

Gamma-aminobutyric acid (GABA) is a non-protein amino acid, which is an important inhibitor of neurotransmission in the human brain. GABA is also used as the precursor of biopolymer Nylon-4 production. In this study, the carbon flux from the tricarboxylic acid cycle was directed to the GABA shunt pathway for the production of GABA from glucose. The GABA shunt enzymes succinate-semialdehyde dehydrogenase (GabD) and GABA aminotransferase (GabT) were co-localized along with the GABA transporter (GadC) by using a synthetic scaffold complex. The co-localized enzyme scaffold complex produced 0.71 g/l of GABA from 10 g/l of glucose. Inactivation of competing metabolic pathways in mutant E. coli strains XBM1 and XBM6 increased GABA production 13% to reach 0.80 g/l GABA by the enzymes co-localized and expressed in the mutant strains. The recombinant E. coli system developed in this study demonstrated the possibility of the pathway of the GABA shunt as a novel GABA production pathway.

• KSBB Journal
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• v.15 no.6
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• pp.615-620
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• 2000

To obtain quality germinated brown rices containing high levels of ${\gamma}$-aminobutyric acid (GABA), chitosan was applied during the brown rice germination. The GABA contents in germinated brown rices (1,035 nmole/g fresh weight) and brown rices germinated by water (771 nmole/g fresh weight) or by lactiv acid (728 nmole/g fresh weight). In addition to the enhancement of GABA, germination in the chitosan solution increased alanine concentration and decreased glutamic acid, aspartic acid and serine concentrations in the brown rices. The activity of glutamate decarboxylase was also enhanced by the chitosan treatment. Furthermore, germination by chitosan reduced fungal contamination markdely, compared with germination by water or germination by lactic acid. These results suggest that quality germinated brown rices containing high levels of GABA can be obtained by chitosan application.

• Journal of Microbiology and Biotechnology
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• v.32 no.6
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• pp.783-791
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• 2022

Gamma-aminobutyric acid (GABA) improves various physiological illnesses, including diabetes, hypertension, depression, memory lapse, and insomnia in humans. Therefore, interest in the commercial production of GABA is steadily increasing. Lactic acid bacteria (LAB) have widely been reported as a GABA producer and are safe for human consumption. In this study, GABA-producing LAB were preliminarily identified and quantified via GABase assay. The acid and bile tolerance of the L. plantarum FBT215 strain were evaluated. The one-factor-at-a-time (OFAT) strategy was applied to determine the optimal conditions for GABA production using HPLC. Response surface methodology (RSM) with Box-Behnken design was used to predict the optimum GABA production. The strain FBT215 was shown to be acid and bile tolerant. The optimization of GABA production via the OFAT strategy resulted in an average GABA concentration of 1688.65 ± 14.29 ㎍/ml, while it was 1812.16 ± 23.16 ㎍/ml when RSM was applied. In conclusion, this study provides the optimum culture conditions for GABA production by the strain FBT215 and indicates that L. plantarum FBT215 is potentially promising for commercial functional probiotics with health claims.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.562-568
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• 2006

GABA $(\gamma-aminobutyric\;acid)$ is the principal inhibitory neurotransmitter in the brain. For the efficient production of GAB A, a semi continuous cell entrapment system using Lactobacillus brevis GABA 057 was optimized, including the substrate concentration, bead-stabilizing additives, and reaction conditions. The converted monosodium glutamate (MSG), which was added as a substrate for glutamic acid decarboxylase (GAD), increased from 2% (w/v) to 12% (w/v). The addition of isomaltooligosaccharide to the alginate beads also increased the stability of the entrapped L. brevis and GABA productivity. Consequently, when optimal conditions were applied, up to 223 mM GABA could be produced from 534 mM MSG after 48 h of reaction by using alginate-beadencapsulated L. brevis GABA 057.

• YAKHAK HOEJI
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• v.43 no.3
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• pp.300-305
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• 1999

A sensitive and efficient assay method was applied to determine the level of glutamic acid (GA) and ${\gamma}-aminobutyric$ acid (GABA) in frontal cortex and hippocampus of rat administrated with ethanol and drugs. The compounds were derivatized with ο-phthalaldehyde (OPA) and 2-mercaptoethanof for precolunm analysis. The condition for the simultaneous determination of GA, GABA and $\beta-aminobutyric$ acid (BABA) by high performance liquid chromatography with electrochemical detection was reverse phase $C_{18}$ column as stationary phase, 0.1 M phosphate buffer containing 0.1 mM $Na_4EDTA$ : methanol = 55:45 (v+v) pH 3.8 as mobile phase and 0.7V electrode voltage. The stability of reaction product of GA, GABA and BABA with OPA could be increased by adding the same volume of polyethylene glycol 400 to reaction mixture. The GABA level in frotal cortex of rat was significantly decreased by the administration of picrotoxin and diazepam, but it was significantly increased by the administration of red ginseng total saponin, N-methyl-D-glucamine and (-)-deprenyl.

• Korean journal of food and cookery science
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• v.29 no.6
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• pp.671-677
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• 2013

The objective of this study was to examine the levels of free amino acids and identify the correlation between ${\gamma}$-aminobutyric acid (GABA)and L-glutamic acid contents in Kimchi during fermentation. During 2 weeks of fermentation, the acidity of Kinchi increased, i.e., the pH level decreased from 5.24 to 4.40. The content of amino acids determined using HPLC differed significantly (p < 0.05) during 7 weeks of fermentation. Over the 7 weeks of fermentation, the content of most free amino acids increased in the order L-valine > L-glutamic acid > L-glycine, except L-methionine decreased. Initially, the GABA content was found to be $72.43{\mu}M/100g$ fresh weight (fw), and it increased to $229.06{\mu}M/100g$ fw after 7 weeks. This rapid increase in the GABA content in the initial stage is considered to be due to L-glutamic acid. However, during the period of 0~7 weeks, no correlations were found between the L-glutamic acid and GABA contents.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1664-1669
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• 2017

Gamma-aminobutyric acid is a precursor of nylon-4, which is a promising heat-resistant biopolymer. GABA can be produced from the decarboxylation of glutamate by glutamate decarboxylase. In this study, a synthetic scaffold complex strategy was employed involving the Neurospora crassa glutamate decarboxylase (GadB) and Escherichia coli GABA antiporter (GadC) to improve GABA production. To construct the complex, the SH3 domain was attached to the N. crassa GadB, and the SH3 ligand was attached to the N-terminus, middle, and C-terminus of E. coli GadC. In the C-terminus model, 5.8 g/l of GABA concentration was obtained from 10 g/l glutamate. When a competing pathway engineered strain was used, the final GABA concentration was further increased to 5.94 g/l, which corresponds to 97.5% of GABA yield. With the introduction of the scaffold complex, the GABA productivity increased by 2.9 folds during the initial culture period.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.737-740
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• 2002

To determine the relations between antihypertensive effect and ${\gamma}-aminobutyric$ acid, mycelial weight and pigment of Monascus, ethanol koji extracts were prepared from Monascus koji and each of three grade was classified based on ${\gamma}-aminobutyric$ acid content, glucosamine content and hue angle value, respectively. Each extract was orally administrated on male spontaneously hypertensive rats and its antihypertensive effect was compared. Most of koji extracts showed antihypertensive activity regardless of their ${\gamma}-aminobutyric$ acid content, glucosamine content or hue angle value. Therefore, hypotensive activity of koji extract was not dependent on above three components.