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- Title
Biosynthesis of Gamma-Aminobutyric Acid by Engineered Clostridium tyrobutyricum Co-Overexpressing Glutamate Decarboxylase and Class I Heat Shock Protein.
- Authors
Liu, Ziyao; Guo, Xiaolong; Dai, Kaiqun; Feng, Jun; Zhou, Tiantian; Fu, Hongxin; Wang, Jufang
- Abstract
Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the mammalian central nervous system that has a significant beneficial effect on human health. Traditional microbial GABA synthesis requires continuous oxygen supplementation. Here, a new anaerobic platform for GABA production was established with engineered C. tyrobutyricum ATCC 25755, which is considered an ideal anaerobic microbial-cell factory for bioproduction. Glutamate decarboxylase (GAD) and Class I heat-shock proteins were screened and overexpressed, generating an excellent Ct-pMAG strain for monosodium-glutamate (MSG) tolerance and GABA production, with a GABA titer of 14.26 g/L in serum bottles with the mixed substrate of glucose and MSG. Fed-batch fermentation was carried out in a 5 L bioreactor, achieving 35.57 g/L and 122.34 g/L final titers of GABA by applying the pH-free strategy and the pH-control strategy, respectively using MSG. Finally, a two-stage strategy (growth stage and bioconversion stage) was applied using glutamate acid (L-Glu) and glucose as the substrate, obtaining a 400.32 g/L final titer of GABA with a productivity of 36.39 g/L/h. Overall, this study provides an anaerobic-fermentation platform for high-level bio-GABA production.
- Subjects
HEAT shock proteins; GLUTAMATE decarboxylase; GABA; BUTYRIC acid; BIOSYNTHESIS; MICROBIOLOGICAL synthesis
- Publication
Fermentation (Basel), 2023, Vol 9, Issue 5, p445
- ISSN
2311-5637
- Publication type
Article
- DOI
10.3390/fermentation9050445