A new metabolic route for the production of gamma-aminobutyric acid by Corynebacterium glutamicum from glucose.
Gamma-aminobutyric acid (GABA), a non-protein amino acid widespread in nature, is a component of pharmaceuticals, foods, and the biodegradable plastic polyamide 4. Corynebacterium glutamicum shows great potential for the production of GABA from glucose. GABA added to the growth medium hardly affected growth of C. glutamicum, since a half-inhibitory concentration of 1.1 M GABA was determined. As alternative to GABA production by glutamate decarboxylation, a new route for the production of GABA via putrescine was established in C. glutamicum. A putrescine-producing recombinant C. glutamicum strain was converted into a GABA producing strain by heterologous expression of putrescine transaminase (PatA) and gamma-aminobutyraldehyde dehydrogenase (PatD) genes from Escherichia coli. The resultant strain produced 5.3 ± 0.1 g L-1of GABA. GABA production was improved further by adjusting the concentration of nitrogen in the culture medium, by avoiding the formation of the by-product N-acetylputrescine and by deletion of the genes for GABA catabolism and GABA re-uptake. GABA accumulation by this strain was increased by 51 % to 8.0 ± 0.3 g L-1, and the volumetric productivity was increased to 0.31 g L-1h-1; the highest volumetric productivity reported so far for fermentative production of GABA from glucose in shake flasks was achieved.
Chair of Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany.
João M P
JM
Jorge
evocatal GmbH, Alfred-Nobel-Str. 10, 40789, Monheim am Rhein, Germany.
Christian
C
Leggewie
Chair of Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany. volker.wendisch@uni-bielefeld.de.
Volker F
VF
Wendisch
D000445:Aldehyde Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D005947:Glucose / Q000378:metabolism*; D000074041:Microorganisms, Genetically-Modified / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D000637:Transaminases / Q000096:biosynthesis / Q000235:genetics; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis* / Q000235:genetics
D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D005680:gamma-Aminobutyric Acid; D000445:Aldehyde Oxidoreductases; C019679:aminobutyraldehyde dehydrogenase; D000637:Transaminases; D005947:Glucose
Corynebacterium glutamicum; Gamma-aminobutyraldehyde dehydrogenase; Gamma-aminobutyrate aminotransferase, GABA; Gamma-aminobutyric acid; Putrescine; Putrescine transaminase