Engineering Escherichia coli for propionic acid production through the Wood–Werkman cycle. Issue 1 (16th October 2019)

• Record Type: Journal Article
• Authors: Gonzalez‐Garcia, Ricardo A.; McCubbin, Timothy; Turner, Mark S.; Nielsen, Lars K.; Marcellin, Esteban
• Is Part Of: Biotechnology and bioengineering. Volume 117:Issue 1(2020)
• Page Start: 167
• Page End: 183
• Publication Date: 2019-10-16
• Subjects: 1‐propanol -- Escherichia coli -- propionate -- propionibacteria -- Wood–Werkman cycle; Biotechnology -- Periodicals; Bioengineering -- Periodicals; 660.6
• DOI: 10.1002/bit.27182
• Languages: English
• ISSNs: 0006-3592

Abstract

Abstract: Native to propionibacteria, the Wood–Werkman cycle enables propionate production via succinate decarboxylation. Current limitations in engineering propionibacteria strains have redirected attention toward the heterologous production in model organisms. Here, we report the functional expression of the Wood–Werkman cycle in Escherichia coli to enable propionate and 1‐propanol production. The initial proof‐of‐concept attempt showed that the cycle can be used for production. However, production levels were low (0.17 mM). In silico optimization of the expression system by operon rearrangement and ribosomal‐binding site tuning improved performance by fivefold. Adaptive laboratory evolution further improved performance redirecting almost 30% of total carbon through the Wood–Werkman cycle, achieving propionate and propanol titers of 9 and 5 mM, respectively. Rational engineering to reduce the generation of byproducts showed that lactate (∆ ldhA ) and formate (∆ pflB ) knockout strains exhibit an improved propionate and 1‐propanol production, while the ethanol (∆ adhE ) knockout strain only showed improved propionate production. Abstract : In this study, the authors built a synthetic version of propionibacteria's Wood Werkman cycle and expressed it in Escherichia coli . The authors demonstrated the feasibility of the heterologous pathway to produce propionic acid. Adaptive laboratory evolution and gene knockout strategies were implemented to redirect the carbon flux through the Wood Werman cycle. The engineered strains have the potential to be used as a model to study further the Wood‐Werkman cycle and to understand better redox balancing in E. coli .