Metabolic Engineering of Escherichia coli for de Novo Production of Betaxanthins

Abstract

Betalains are emerging natural pigments with high tinctorial strength and stability, physiological activities, and fluorescent properties for potential application in food, cosmetic, and pharmaceutical industries. Betalains including yellow betaxanthins and red betacyanins are mainly restricted in the Caryophyllales plants. To expand the availability of individual betaxanthins, here, we constructed an Escherichia coli BTA6 for de novo biosynthesis of betalamic acid. Using this strain as a monoculture platform, 14 yellow and 2 red betaxanthins were produced by feeding amino acids and amines. Furthermore, we constructed an l-histidine overproducing strain using chromosome engineering to deattenuate regulation and established a coculture system. After optimization of the initial inoculation ratios and fermentation conditions, the compatible and robust coculture system produced 287.69 mg/L of histidine-betaxanthin. This is the first report on de novo production of betaxanthins in engineered E. coli using glucose as a carbon source. Our work highlights the feasibility of microbial cell factories to produce individual betalains.

Modular engineering of E. coli coculture for efficient production of resveratrol from glucose and arabinose mixture

“…After resveratrol was efficiently produced from p-coumaric acid, we further extended the resveratrol biosynthesis from glucose. For producing p-coumaric acid from glucose, we used our previously reported l -tyrosine overproducing strain BAK11(DE3) [ 26 ] as chassis. For screening the expression pattern compatible with chassis, the PcTAL gene from Phanerochaete chrysosporium [ 27 ] under the control of the trc promoter was cloned into various copy number plasmids pACYCDuet-1, pCDFDuet-1, and pETDuet-1, and transformed into strain BAK11(DE3) to generate strains BCR1, BCR2, and BCR3, respectively.…”

“…To increase the intracellular availability of malonyl-CoA, we applied the RppA biosensor [ 25 ] for screening CRISPRi inhibitory targets. The upstream strain was constructed from arabinose-deficient and l -tyrosine-overproducer [ 26 ] by introducing the PcTAL gene [ 27 ]. To stabilize the subpopulation in coculture system, we designed and constructed a resveratrol addiction circuit in the upstream strain that coupled its growth with the resveratrol production of the downstream strain.…”

Metabolic Division in an Escherichia coli Coculture System for Efficient Production of Kaempferide

“…For the de novo biosynthesis of kaempferide, we chose the PcTAL gene from Phanerochaete chrysosporium 42 as the upstream module and tyrosine overproducing strain BAK11-(DE3) as the chassis host, which was constructed previously in our lab. 44 PcTAL and At4CL were coexpressed in pCDFduet-1 and transformed with pESI1 and pEOM9 into BAK11(DE3). As shown in Figure 5, the resulting strain BANS2 produced a small amount of kaempferide (1.6 ± 0.1 mg/L) with growth arrest, while the accumulation of p-coumaric acid was massive (773.2 ± 23.2 mg/L).…”

Plant-Derived Cell-Free Biofactories for the Production of Secondary Metabolites

“…The production of betalains has also been transferred to microbes by metabolic engineering. Various betaxanthins and betacyanins have been produced in E. coli, with yields of up to 288 mg per L (Guerrero-Rubio et al, 2019;Hou et al, 2020). Grewal et al (2018) reported the production of betalains in the yeast S. cerevisiae, achieving a titer of 17 µg per mL for betanin, the most industrially relevant betalain.…”