The two-step biotransformation of monosodium glutamate to GABA by Lactobacillus brevis growing and resting cells.
Gama-aminobutyric acid (GABA) is a natural functional amino acid. In the current study, Lactobacillus brevis TCCC13007, a high GABA-producing strain, was isolated from naturally pickled Chinese vegetables. A two-step cellular bioconversion process was established using L. brevis TCCC13007 for the production of GABA. First, L. brevis cells were grown anaerobically in 7% monosodium glutamate (MSG)-containing medium at an initial pH of 6.0 and a controlled pH of 4.6 for 16 to 66 h; approximately 38 g L(-1) of GABA was obtained after 66 h of fermentation at a conversion rate of 98.6%. In the second stage of the process, about 7.6 g L(-1) of GABA was produced three more times at a conversion rate of 92.2% using the same batch of resting cells in the substrate-containing buffer under optimized conditions. Thus, the total GABA yield reached 61 g L(-1). A model system for the biotransformation of MSG to GABA was established using L. brevis TCCC13007 resting cells. The reaction rates were found to follow the classic Michaelis-Menten equation at low substrate concentrations (<80 mM). Kinetic analysis of the biotransformation revealed that L. brevis TCCC13007 resting cells produced GABA similar to that produced by purified glutamate decarboxylase from L. brevis.
Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, TEDA, Tianjin 300457, People's Republic of China.
Ying
Y
Zhang
Lei
L
Song
Qiang
Q
Gao
Shao Mei
SM
Yu
Lei
L
Li
Nian Fa
NF
Gao
D001711:Biotransformation; D005285:Fermentation; D007700:Kinetics; D052196:Levilactobacillus brevis / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D012970:Sodium Glutamate / Q000378:metabolism*; D014675:Vegetables / Q000382:microbiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005680:gamma-Aminobutyric Acid; D012970:Sodium Glutamate