Implication of ornithine acetyltransferase activity on l‐ornithine production in Corynebacterium glutamicum

Abstract

l-Ornithine is an intermediate of the l-arginine biosynthetic pathway in Corynebacterium glutamicum. The effect of ornithine acetyltransferase (OATase; ArgJ) on l-ornithine production was investigated, and C. glutamicum 1006 was engineered to overproduce l-ornithine as a major product by inactivating regulatory repressor argR gene and overexpressing argJ gene. A genome sequence analysis indicated that the argF gene encoding ornithine carbamoyltransferase in C. glutamicum 1006 was mutated, resulting in the accumulation of a certain amount of l-ornithine (20.5 g/L). The assays using a crude extract of C. glutamicum 1006 indicated that the l-ornithine concentration for 50% inhibition of OAT was 5 mM. To enhance l-ornithine production, the argJ gene from C. glutamicum ATCC 13032 was overexpressed. In flask cultures, the resulting strain, C. glutamicum 1006∆argR-argJ, produced 31.6 g/L l-ornithine, which is 54.15% more than that produced by C. glutamicum 1006. The OAT activity of C. glutamicum 1006∆argR-argJ was significantly greater than that of C. glutamicum 1006, and this study achieved the highest conversion ratio of sugar to acid (0.396 g/g) compared with those of previous reports. ArgJ strongly influences the production of l-ornithine in C. glutamicum.

Improvement of l-ornithine production by attenuation of argF in engineered Corynebacterium glutamicum S9114

“…Cell growth was monitored by measuring the optical density of the culture at 600 nm (OD 600 ) using an spectrophotometer, after dilution of the culture with 0.125 mol/L HCl to dissolve CaCO 3 (Hao et al 2016). The production of l -ornithine was determined by ninhydrin colorimetry, as described previously (Chinard 1952).…”

Optimization of ʟ-ornithine production in recombinant Corynebacterium glutamicum S9114 by cg3035 overexpression and manipulating the central metabolic pathway

“… [ 10 ] SJC8039 ∆ ncgl0281 ∆ ncgl2582 ∆ ncgl2053 14 a ND Shake flask; batch Deletion of argF , argR , and proB ; Blocking gluconate biosynthesis [ 11 ] ∆APE6937R42 24.1 0.298 Bioreactor; batch Deletion of argF , argR , and proB ; Adaptive evolution in presence of ʟ-ornithine [ 13 ] 1006∆ argR - argJ 31.6 0.396 Shake flask; batch Deletion of argR ; overexpression of argJ . [ 31 ] a These values were not described in the main text of the original reference and thus estimated from the figure or graph …”

Recent Advances of L-ornithine Biosynthesis in Metabolically Engineered Corynebacterium glutamicum

“…Hence, the argR gene was deleted in all the engineered L-ornithine-producing C. glutamicum strains, which provided a powerful strategy for improving the L-ornithine production titer. Inactivation of argR in the C. glutamicum 1006 strain improved the yield of L-ornithine (from 20.5 to 28.3 g/L) and yield from 0.256 to 0.354 g/g glucose (Hao et al, 2016). However, the yield of L-ornithine did not improve further upon overexpression of the argCJBD operon by employing a plasmid or by inserting a strong promoter as the ArgR repressor was absent (Zhang B. et al, 2017;Zhang et al, 2018a).…”

“…For feedback inhibition of L-ornithine, the enzyme activity of ornithine acetyltransferase (encoded by argJ) was inhibited by 50% by using 5 mM L-ornithine. The overexpression of argJ increased the yield of L-ornithine from 28.3 to 31.6 g/L in the engineered C. glutamicum 1006 strain (Hao et al, 2016). However, the mechanism underlying the inhibition of ornithine acetyltransferase by L-ornithine has not been elucidated.…”