• Korean Journal of Microbiology
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• v.47 no.4
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• pp.316-322
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• 2011

Lactobacillus sakei OPK2-59 isolated from kimchi was found to have ${\gamma}$-aminobutyric acid (GABA) producing ability and glutamate decarboxylase (GAD) activity. When the Lactobacillus sakei OPK2-59 was cultured in MRS broth with 59.13 mM and 177.40 mM monosodium glutamate (MSG), the optimum temperature range and pH for growth were $25-37^{\circ}C$ and pH 6.5, respectively. GABA conversion rates in MRS broth with 59.13 mM and 177.40 mM MSG were 99.58% and 31.00%, respectively at $25^{\circ}C$ and 48 h of cultivation. By using the cell free extract of Lactobacillus sakei OPK2-59, MSG was converted to GABA and the conversion rate was 78.51% at $30^{\circ}C$, pH 5. Conversion of MSG to GABA was enhanced by adding salts such as $CaCl_2$, $FeCl_3$, $MgCl_2$. These data suggest that the ability of Lactobacillus sakei OPK2-59 to produce GABA results from the activity of GAD in the cells and GABA conversion by the cell extract containing GAD can be enhanced by $CaCl_2$, $FeCl_3$, $MgCl_2$.

• Mycobiology
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• v.45 no.3
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• pp.199-203
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• 2017

This study was done to produce ${\gamma}$-aminobutyric acid (GABA) from wild yeast as well as investigate its anti-hyperglycemic effects. Among ten GABA-producing yeast strains, Pichia silvicola UL6-1 and Sporobolomyces carnicolor 402-JB-1 produced high GABA concentration of $134.4{\mu}g/mL$ and $179.2{\mu}g/mL$, respectively. P. silvicola UL6-1 showed a maximum GABA yield of $136.5{\mu}g/mL$ and $200.8{\mu}g/mL$ from S. carnicolor 402-JB-1 when they were cultured for 30 hr at $30^{\circ}C$ in yeast extract-peptone-dextrose medium. The cell-free extract from P. silvicola UL6-1 and S. carnicolor 402-JB-1 showed very high anti-hyperglycemic ${\alpha}$-glucosidase inhibitory activity of 72.3% and 69.9%, respectively. Additionally, their cell-free extract-containing GABA showed the anti-hyperglycemic effect in streptozotocin-induced diabetic Sprague-Dawley rats.

• Korean Journal of Organic Agriculture
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• v.25 no.1
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• pp.171-185
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• 2017

${\gamma}$-aminobutyric acid (GABA) is a non-proteinogenic amino acid biosynthesized through decarboxylation of L-glutamic acid by glutamic acid decarboxylase. GABA is believed to play a role in defense against stress in plants. In humans, it is known as one of the major inhibitory neurotransmitters in the central nervous system, exerting anti-hypertensive and anti-diabetic effects. In this report, we wanted to enhance the GABA production from the barley leaf and corn silk by culturing them with lactic acid bacteria (LAB). The barley leaf and corn silk were mixed with various weight combinations and were fermented with Lactobacillus plantarum in an incubator at $30^{\circ}C$ for 48 h. After extracting the fermented mixture with hot water, we evaluated the GABA production by thin layer chromatography and GABase assay. We found that the fermented mixture of the barley leaf and corn silk in a nine to one ratio contained a higher level of GABA than other ratios, meaning that the intermixture and fermentation technique was effective in increasing the GABA content. We also tested several biological activities of the fermented extracts and found that the extracts of the fermented mixture showed improved antioxidant activities than the non-fermented extracts and no indication of cytotoxicity. These results suggest that our approach on combining the barley leaf and corn silk and its fermentation with LAB could lead to the possibility of the development of functional foods with high levels of GABA content and improved biological activities.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.978-984
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• 2024

Genome-scale metabolic model (GEM) can be used to simulate cellular metabolic phenotypes under various environmental or genetic conditions. This study utilized the GEM to observe the internal metabolic fluxes of recombinant Escherichia coli producing gamma-aminobutyric acid (GABA). Recombinant E. coli was cultivated in a fermenter under three conditions: pH 7, pH 5, and additional succinic acids. External fluxes were calculated from cultivation results, and internal fluxes were calculated through flux optimization. Based on the internal flux analysis, glycolysis and pentose phosphate pathways were repressed under cultivation at pH 5, even though glutamate dehydrogenase increased GABA production. Notably, this repression was halted by adding succinic acid. Furthermore, proper sucA repression is a promising target for developing strains more capable of producing GABA.

• Preventive Nutrition and Food Science
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• v.9 no.1
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• pp.58-64
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• 2004

This study investigated the effects of carnitine and/or ${\gamma}$ -aminobutyric acid (GABA) supplementation on lipid profiles and some immune related nutrient in mice. Balb/c male mice were orally treated with either an AIN-76 diet (Con), a control diet plus carnitine (CS, 0.5 g/kg bw), a control diet plus GABA (GS, 0.5 g/kg bw) or a control diet plus carnitine plus GABA (CGS, 0.25 g/kg bw, respectively) for 6 weeks. There were no significant differences in feed consumption, energy intake, body weight gain or feed efficiency ratio among the groups during the experimental period. However, abdominal fat deposits were smaller in CS, GS and CGS groups compared with the Con group. Serum and liver triglycerides also were lower in CS, GS and CGS and serum total cholesterol was significantly lower in the CGS group compared with the Con group. Serum LDL cholesterol was lower in the CGS group and liver HDL cholesterol was significantly higher in the CS group compared with Con group. In serum, stearic acid and selecholeic acid were lower, but arachidic acid was higher in the CS group. Liver stearic acid was higher but oleic acid lower in CGS group compared with Con group. In carnitine supplemented groups, serum and liver nonesterified carnitine (NEC), acidsoluble acylcarnitine (ASAC), total carnitine (TCNE) concentrations were higher in only the CS group, not CGS group. Serum vitamin A and E concentrations were not different among the groups. These results may suggest that carnitine and/or GABA supplementation improves lipid profiles in mice, but did not affect the immune-related nutrients that we measured under the experimental conditions of this study.

• Journal of Applied Biological Chemistry
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• v.56 no.2
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• pp.89-93
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• 2013

Gamma-aminobutyric acid (GABA) aminotransferase (gabT) and succinic semialdehyde dehydrogenase (gabD) genes from Pseudomonas fluorescens KCCM 12537 were cloned into a single pETDuet-1 vector and co-expressed in Escherichia coli BL21(DE3) simultaneously. The mixture of both enzymes, called GABase, is the key enzyme for the enzymatic analysis of GABA. The molecular mass of the GABA aminotransferase and succinic semialdehyde dehydrogenase were determined to be 52.8 and 46.7 kDa following computations performed with the pI/Mw program, respectively. The GABase activity between pH 6.0 and 9.0 for 24 h at $4^{\circ}C$ remained over 75%, but under pH 6.0 decreased rapidly. The GABase activity between 25 and $35^{\circ}C$ by the treatment at pH 8.6 for 30 min remained over 80%, but over $35^{\circ}C$ decreased rapidly. When the activity against GABA was defined as 100%, the purified GABase activity against 5-aminovaleric acid having a similar structure to GABA showed 47.7% and GABase activity against ${\beta}$-alanine, ${\varepsilon}$-amino-n-caproic acid, $_L$-ornithine, $_L$-lysine, and $_L$-aspartic acid showed between 0.3 to 2.3%. The GABA content was analyzed with this co-expressed GABase, compared with the other GABase which was available commercially. As a result, the content of GABA extracted from brown rice, dark brown rice, and black rice were $26.4{\pm}3.5$, $40.5{\pm}4.7$ and $94.7{\pm}9.3{\mu}g/g$, which were similar data of other GABase in the error ranges.

• Applied Biological Chemistry
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• v.43 no.1
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• pp.34-38
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• 2000

To investigate the effects of chitosan on growth and quality improvement of vegetables, we utilized cabbage as a model plant system and SL-chitosan as a chitosan fertilizer. The chitosan fertilizer treatment increased the leaf lengths of cabbage seedlings compared with those of control groups. In addition, the content of ${\gamma}-aminobutyric$ acid (GABA) in the fertilizer-treated cabbage seedlings was higher than that in the control group. Peripheral lengths and head weights of cabbages along with their GABA contents were also measured during the growth of cabbages in field. The fertilizer treatment, without changing the physico-chemical properties of main field soil after the cultivation of cabbage, significantly increased the peripheral length, average weight and GABA content compared with control treatment. These results may suggest that the quality and quantity of cabbage can be improved by chitosan treatments.

• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.933-943
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• 2019

Gamma-aminobutyric acid (GABA)-producing strains were isolated from four edible insects and subjected to 16S rRNA sequence analysis. Among the four GABA-producing bacteria, Enterococcus avium JS-N6B4 exhibited the highest GABA-production, while cultivation temperature, initial pH, aerobic condition, and mono-sodium glutamate (MSG) feeding were found to be the key factors affecting GABA production rate. The culture condition was optimized in terms of glucose, yeast extract, and MSG concentrations using response surface methodology (RSM). GABA production up to 16.64 g/l was obtained under the conditions of 7 g/l glucose, 45 g/l yeast extract, and 62 g/l MSG through the optimization of medium composition by RSM. Experimental GABA production was 13.68 g/l, which was close to the predicted value (16.64 g/l) calculated from the analysis of variance, and 2.79-fold higher than the production achieved with basic medium. Therefore, GABA-producing strains may help improve the GABA production in edible insects, and provide a new approach to the use of edible insects as effective food biomaterials.

• Journal of Life Science
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• v.20 no.7
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• pp.1005-1011
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• 2010

$\gamma$-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system. GABA transporters (GATs) control extracellular GABA levels by reuptake of released GABA from the synaptic cleft. However, how GATs are regulated has not yet been elucidated. Here, we used the yeast two-hybrid system to identify the specific binding protein(s) that interacts with the carboxyl (C)-terminal region of GAT1, the major isoform in the brain and find a specific interaction with the ubiquitin-specific protease 14 (Usp14), a deubiquitinating enzyme. Usp14 protein bound to the tail region of GAT1 and GAT2 but not to other GAT members in the yeast two-hybrid assay. The C-terminal region of Usp14 is essential for interaction with GAT1. In addition, these proteins showed specific interactions in the glutathione S-transferase (GST) pull-down assay. An antibody to GAT1 specifically co-immunoprecipitated Usp14 from mouse brain extracts. These results suggest that Usp14 may regulate the number of GAT1 at the cell surface.

• Journal of Applied Biological Chemistry
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• v.43 no.2
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• pp.69-73
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• 2000

In order to understand the biological role of calmodulin in plants, transgenic plants expressing a mutant calmodulin (VU-4, Iys to ile-115) have been analyzed. We found that tobacco plants expressing VU-4 calmodulin have approximately twofold higher $\gamma$-aminobutyric acid (GABA) levels than the control plants. Cell suspension cultures established from the stem explants of the transgenic tobacco seedlings also have higher levels of GABA than the control cell cultures. Specific activity of glutamate decarboxylase (GAD), which catalyzes the decarboxylation of glutamate to $CO_2$ and GABA, of the transgenic tobacco cell extracts was about twofold higher than the activity of the control cell extracts. Western-blot analysis showed that the GAD is highly expressed in the transgenic tobacco plants. GAD partially purified from tobacco cell extracts showed approximately threefold $Ca^{2+}$/calmodulin-dependent activation. These data suggest that GABA synthesis in the transgenic tobacco plants is elevated, possibly due to higher levels of the calmodulin-dependent GAD enzyme and/or as a result of enhanced activation due to increased levels of the foreign calmodulin.