Metabolic engineering of Corynebacterium glutamicum for anthocyanin production

Abstract

BackgroundAnthocyanins such as cyanidin 3-O-glucoside (C3G) have wide applications in industry as food colorants. Their current production heavily relies on extraction from plant tissues. Development of a sustainable method to produce anthocyanins is of considerable interest for industrial use. Previously, E. coli-based microbial production of anthocyanins has been investigated extensively. However, safety concerns on E. coli call for the adoption of a safe production host. In the present study, a GRAS bacterium, Corynebacterium glutamicum, was introduced as the host strain to synthesize C3G. We adopted stepwise metabolic engineering strategies to improve the production titer of C3G.ResultsAnthocyanidin synthase (ANS) from Petunia hybrida and 3-O-glucosyltransferase (3GT) from Arabidopsis thaliana were coexpressed in C. glutamicum ATCC 13032 to drive the conversion from catechin to C3G. Optimized expression of ANS and 3GT improved the C3G titer by 1- to 15-fold. Further process optimization and improvement of UDP-glucose availability led to ~ 40 mg/L C3G production, representing a > 100-fold titer increase compared to production in the un-engineered, un-optimized starting strain.ConclusionsFor the first time, we successfully achieved the production of the specialty anthocyanin C3G from the comparatively inexpensive flavonoid precursor catechin in C. glutamicum. This study opens up more possibility of C. glutamicum as a host microbe for the biosynthesis of useful and value-added natural compounds.Electronic supplementary materialThe online version of this article (10.1186/s12934-018-0990-z) contains supplementary material, which is available to authorized users.

Pathway enzyme engineering for flavonoid production in recombinant microbes

“…For example, to engineer C. glutamicum for the biosynthesis of cyanidin 3- O -glucoside from catechin, SUMO tag was fused to the N-terminus of flavonoid 3- O- glucosyltransferase to improve its expression. The fusion enzyme allowed a 1.1-fold increase in the production of cyanidin 3- O -glucoside (Zha et al., 2018).…”

Engineering Corynebacterium glutamicum to produce the biogasoline isopentenol from plant biomass hydrolysates

“…A previous study also examined the impact of C:N ratio on the production of a native molecule [45], but testing a range of C:N values is not yet common practice when characterizing new products. The absolute starting d -glucose concentration (or C:N ratio) may be a general determinant of final product titer and could be beneficial for optimizing other heterologous gene pathways in C. glutamicum , such as for the production of the anthocyanin food colorant, cyanidin 3- O -glucoside [46].…”

Metabolic Engineering of Microorganisms for the Production of Flavonoids

“…Except E. coli and S. cerevisiae , several other microorganisms have also demonstrated the ability to synthesize anthocyanins. Zha et al (2018) constructed a recombinant C. glutamicum strain to produce cyanidin 3- O -glucoside from catechin by overexpression of ANS from P. hybrida and 3GT from A. thaliana . Further adjustment of the expression level of ANS and 3GT, process optimization, and improvement of UDP-glucose availability enabled the production of 40 mg/L cyanidin 3- O -glucoside ( Zha et al, 2018 ).…”

“… Zha et al (2018) constructed a recombinant C. glutamicum strain to produce cyanidin 3- O -glucoside from catechin by overexpression of ANS from P. hybrida and 3GT from A. thaliana . Further adjustment of the expression level of ANS and 3GT, process optimization, and improvement of UDP-glucose availability enabled the production of 40 mg/L cyanidin 3- O -glucoside ( Zha et al, 2018 ). In another study, the Lactococcus lactis was engineered to produce some unusual anthocyanins using tea as substrate.…”