Project description:Corynebacterium glutamicum shows a great potential for the production of gamma-aminobutyric acid (GABA) from glucose fermentation via putrescine. GABA, a non-protein amino acid widespread in nature, is a component of pharmaceuticals, foods and the biodegradable plastic polyamide 4. Here, the effect of GABA in the growth of C. glutamicum was evaluated. It was estimated that the presence 1.1 M of GABA in the medium reduces the maximum growth rate of C. glutamicum to half. It was also shown that the presence of GABA in the medium negatively affects the growth of C. glutamicum in ethanol as sole carbon source. Furthermore, a new route for the production of GABA in C. glutamicum was established. GABA production from glucose fermentation via putrescine was achieved by plasmid-based overexpression of putrescine transaminase (PatA) and gamma-aminobutyraldehyde dehydrogenase (PatD) in a putrescine production strain. The resultant strain can produce 5.3 ± 0.1 g L-1 of GABA. GABA production was improved by avoiding the formation of N-acetylputrescine and by reducing the amount of nitrogen in CGXII medium. Deletion of the genes responsible for GABA catabolism and GABA re-uptake led to an increase in the GABA production of 21% achieving a titer 8.0 ± 0.3 g L-1 and an increase in the volumetric productivity of 41% reaching a productivity of 0.31 g L-1 h-1, the highest volumetric productivity achieved so far for GABA production in C. glutamicum from glucose fermentation in flasks fermentations. The results obtained hitherto are very promising and competitive compared to the traditional pathway for the production of GABA.
Project description:Metabolically engineered Corynebacterium glutamicum strains were constructed for the enhanced production of L-arginine, and their gene expression profiles were investigated
Project description:Improved Fermentative Production of Gamma-Aminobutyric Acid via the Putrescine Route: Systems Metabolic Engineering for Production From Glucose, Amino Sugars, and Xylose
Project description:Metabolically engineered Corynebacterium glutamicum strains were constructed for the enhanced production of L-arginine, and their gene expression profiles were investigated Gene expression profiles of two C. glutamicum strains AR2 and AR6 were examined for the 3043 genes twice.
Project description:5-aminovalerate (5AVA), L-lysine derived compound, represents a potential building block for the production of the bio-plastic nylon-5. Escherichia coli has been engineered for the production of 5AVA, but Corynebacterium glutamicum has never been engineered for the production of 5AVA, but, a lot of work was done in the last decades to optimize the production of the precursor L-lysine and more recently cadaverine. 5AVA added to the growth medium hardly affected growth rate of C. glutamicum, since, a half-inhibitory concentration of 1.1 M 5AVA was determined. While in E. coli, 5AVA production was engineered by using the DavBA pathway from Pseudomonas putida, here a pathway based on the route described in P. aeruginosa was established. C. glutamicum wild type was converted into a 5AVA producing strain by heterologous expression of L-lysine decarboxylase (LdcC), putrescine transaminase (PatA) and γ-aminobutyraldehyde dehydrogenase (PatD) genes from E. coli. 5AVA production was improved by using a strain previously engineered for high L-lysine production, by de-repressing phosphoenolpyruvate phosphotransferase system (PTS) and glycolysis and by avoiding formation of the by-product L-lactate. 5AVA accumulation by this strain was increased to 44.9 mM, representing a yield of 202 mmol mol-1 glucose, which is about three times higher than the highest yield achieved in E. coli for the production of 5AVA from glucose fermentation.
Project description:To identify genes which are differentially expressed in Corynebacterium glutamicum in the cg2699 deletion strain, we performed DNA microarray analyses of C. glutamicum Δcg2699 compared to the WT.
Project description:To identify genes which are differentially expressed in Corynebacterium glutamicum in the cg2460 deletion strain, we performed DNA microarray analyses of C. glutamicum Δcg2460 compared to the WT.
Project description:Recently, we established Corynebacterium glutamicum as a suitable production host for various bacteriocins including garvicin Q (GarQ). Here, we establish secretion of GarQ by C. glutamicum via the Sec translocon. At neutral pH, the cationic peptide is efficiently adsorbed to the negatively charged envelope of producer bacteria limiting availability of the bacteriocin in culture supernatants. Using a reporter strain and proteomic analyses, we identified HtrA, a protease associated with secretion stress, as another potential factor limiting GarQ production.
Project description:For the establishment of synthetic microbial communities comprising complementary auxotrophic strains, transport processes for common goods are extremely important. Most auxotrophic strains reach wild type level growth with external supplementation of the required metabolite. One exception was the tryptophan auxotrophic strain Corynebacterium glutamicum ΔTRP ΔtrpP, which grew about 35% slower than the wild type in supplemented minimal medium. Corynebacterium glutamicum ΔTRP ΔtrpP lacks the whole tryptophan biosynthesis cluster (TRP) as well as the putative tryptophan transporter TrpP. We wanted to explore the role of TrpP in tryptophan transport or synthesis and to unravel the cause for the growth limitation of the auxotrophic strain.