• 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.

• 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.

• 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.

• Animal Bioscience
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• v.36 no.2
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• pp.248-255
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• 2023

Objective: Stress factors such as high temperatures, overcrowding, and diurnal temperature range exert profound negative effects on weight gain and productivity of broiler chickens. The potential of gamma aminobutyric acid (GABA) as an excitatory neurotransmitter was evaluated under various stress conditions in this study. Methods: The experiment was conducted under four different environmental conditions: normal, high temperature, overcrowded, and in an overcrowded-diurnal temperature range. The experimental groups were divided into (-) control group without stress, (+) control group with stress, and G50 group (GABA 50 mg/kg) with stress. Weight gain, feed intake, and feed conversion ratio were measured, and stress reduction was evaluated through hematologic analysis. Results: The effects of GABA on broilers in four experimental treatments were evaluated. GABA treated responded to environmental stress and improved productivity in all the experimental treatments. The magnitude of stress observed was highest at high temperature, followed by the overcrowded environment, and was least for the overcrowded-diurnal temperature range. Conclusion: Various stress factors in livestock rearing environment can reduce productivity and increase disease incidence and mortality rate. To address these challenges, GABA, an inhibitory neurotransmitter, was shown to reduce stress caused due to various environmental conditions and improve productivity.

• 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.

• Journal of Mushroom
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• v.15 no.2
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• pp.88-93
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• 2017

This study was carried out to establish a cultivation technique for increasing the ${\gamma}$-aminobutyric acid (GABA) content in the fruit body of mushrooms by adding processed by-products. For the oyster mushroom 'Heucktari', addition of green tea powder, sea tangle powder, and green tea dregs resulted in very poor primordia formation, fruit body growth, and increased GABA. However, addition of 10% schizandra berry dregs and 1% rice bran to the basal substrate induced 100% and 10% increases, in GABA content in the fruit bodies compared to the control treatment without by-product, respectively. In addition, fruit body growth and primordia formation were greatly increased by these treatments. Therefore, GABA content was increased when the substrate was prepared by mixing an appropriate amount of schizandra berry dregs and rice bran.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.652-657
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• 2015

To produce mulberry-leaf tea abundant in ${\gamma}$-aminobutyric acid (GABA), mulberry leaves were subjected to two distinct anaerobic conditions ($N_2$ and vacuum) for 12 h before the manufacturing process. Subsequently, changes in the GABA content as well as that of other components were measured. In anaerobically treated mulberry leaves, GABA content markedly increased by 436-472% compared with the control, while the glutamic acid content decreased. However, few changes were observed in the contents of the general components (moisture, carbohydrate, lipid, protein, and ash) and water-soluble solids. Free sugar, catechin, and total phenol content decreased after anaerobic treatment. However, the sensory test scores were not different between the control and anaerobically-treated samples. Consequently, tea products, manufactured post nitrogen gas or vacuum treatment of leaves after harvest, showed functional properties without sensory loss.

• Bulletin of Food Technology
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• v.13 no.4
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• pp.131-133
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• 2000

• Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.293-297
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• 2012

${\gamma}$-Aminobutyric acid-enriched sea tangle extract was obtained from the fermentation of Lactobacillus brevis BJ-20. The fermented sea tangle extract (FST) was separated into three fractions by molecular weight: FST I (greater than 10 kDa), FST II (1-10 kDa), and FST III (less than 1 kDa). The anti-inflammatory characteristics of the FST fractions were investigated by measuring the production of nitric oxide (NO) and the expression levels of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-induced mouse macrophage (RAW 264.7) cells. Both NO production and iNOS expression levels were significantly inhibited by FST treatments in a dose-dependent manner. FST III was the most effective inhibitor of processes. This demonstrates that the effect of FST on LPS-induced inflammation might be closely correlated with the inhibition of inflammatory cytokine expression.

• Journal of Mushroom
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• v.11 no.4
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• pp.181-186
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• 2013

${\gamma}$-Aminobutyric acid(GABA) is a four carbon non-protein amino acid that has several well-known physiological functions, such as a postsynaptic inhibitory neurotransmitter in the brain and induction of hypotensive and tranquilizer effects. A lactic acid bacterium was isolated from button mushroom bed, which is showing high GABA productivity by TLC or HPLC analysis. The strain was identified as Lactobacillus hilgardii by analysis of 16S rDNA gene sequence. When the maximum production of GABA by L. hilgardii was investigated with various concentration of monosodium glutamate, the yield of GABA reached to be 53.65 mM at 1% mono sodium glutamate (MSG) in flask cultivation. A Glutamate decarboxylase (GAD) enzyme, which was known to convert MSG to GABA, was purified from a cell-free extract of L. hilgardii and the molecular weights of purified GAD was estimated to 60,000 by SDS-PAGE. The optimum pH and temperature of GAD were at pH4.6 and at $37^{\circ}C$, respectively. The GAD activity was increased by the addition of sulfate ions such as ammonium sulfate, sodium sulfate and magnesium sulfate, indicating that the increase of hydrophobic interaction causes the increase of GAD activity.