Characterization of the Recombinant Glutamate Decarboxylase of Lactobacillus brevis G144 Isolated from Galchi Jeotgal, a Korean Salted and Fermented Seafood
2021
Kim, J.A. | Park, J.Y. | Kim, J.H.
A γ-aminobutyric acid (GABA)-producing microorganism was isolated from galchi (hairtail fish, Trichiurus lepturus) jeotgal, a Korean salted and fermented seafood. The G144 isolate produced GABA excessively when incubated in MRS broth containing monosodium glutamate (MSG, 3%, w/v). G144 was identified as Lactobacillus brevis through 16S rRNA and recA gene sequencing. gadB and gadC encoding glutamate decarboxylase (GAD) and glutamate/GABA antiporter, respectively, were cloned and gadB was located downstream of gadC. The operon structure of gadCB was confirmed by reverse transcription (RT)-polymerase chain reaction. gadB was overexpressed in Escherichia coli and recombinant GAD was purified and its size was 54.4 kDa as evidenced by SDS-PAGE results. Maximum GAD activity was observed at pH 5.0 and 40℃ and the activity was dependent on pyridoxal 5'-phophate. The Kₘ and Vₘₐₓ of GAD were 8.6 mM and 0.01 mM/min, respectively.
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