Enhanced production of gamma-aminobutyrate (GABA) in recombinant Corynebacterium glutamicum by expressing glutamate decarboxylase active in expanded pH range. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Choi, Jae; Yim, Sung; Lee, Seung; Kang, Taek; Park, Si; Jeong, Ki
• Is Part Of: Microbial cell factories. Volume 14:Issue 1(2015)
• Page Start: 1
• Page End: 11
• Publication Date: 2015-12
• Subjects: Corynebacterium glutamicum -- Gamma-aminobutyrate -- Glutamate -- Glutamate decarboxylase -- Biotin -- Fed-batch cultivation; Microbial biotechnology -- Periodicals; Recombinant proteins -- Synthesis -- Periodicals; 660.62
• DOI: 10.1186/s12934-015-0205-9
• Languages: English
• ISSNs: 1475-2859

Abstract

Abstract Background Gamma-aminobutylate (GABA) is an important chemical in pharmacetucal field and chemical industry. GABA has mostly been produced in lactic acid bacteria by addingL -glutamate to the culture medium sinceL -glutamate can be converted into GABA by inherentL -glutamate decarboxylase. Recently, GABA has gained much attention for the application as a major building block for the synthesis of 2-pyrrolidone and biodegradable polyamide nylon 4, which opens its application area in the industrial biotechnology. Therefore, Corynebacterium glutamicum, the majorL -glutamate producing microorganism, has been engineered to achieve direct fermentative production of GABA from glucose, but their productivity was rather low. Results RecombinantC. glutamicum strains were developed for enhanced production of GABA from glucose by expressingEscherichia coli glutamate decarboxylase (GAD) mutant, which is active in expanded pH range. Synthetic PH36, PI16, and PL26 promoters, which have different promoter strengths inC. glutamicum, were examined for the expression ofE. coli GAD mutant.C. glutamicum expressingE. coli GAD mutant under the strong PH36 promoter could produce GABA to the concentration of 5.89 ± 0.35 g/L in GP1 medium at pH 7.0, which is 17-fold higher than that obtained byC. glutamicum expressing wild-typeE. coli GAD in the same condition (0.34 ± 0.26 g/L). Fed-bath culture ofC. glutamicum expressingE. coli GAD mutant in GP1 medium containing 50 μg/L of biotin at pH 6, culture condition of which was optimized in flask cultures, resulted in the highest GABA concentration of 38.6 ± 0.85 g/L with the productivity of 0.536 g/L/h. Conclusion RecombinantC. glutamicum strains developed in this study should be useful for the direct fermentative production of GABA from glucose, which allows us to achieve enhanced production of GABA suitable for its application area in the industrial biotechnology.