Metabolic pathway balancing and its role in the production of biofuels and chemicals

Abstract

In the last decade, metabolic engineering benefited greatly from systems and synthetic biology due to substantial advancements in those fields. As a result, technologies and methods evolved to be more complex and controllable than ever. In this review, we highlight up-to-date case studies using these techniques, examine their potential, and stress their importance for production of compounds such as fatty acids, alcohols, and high value chemicals. Beginning with basic rational control techniques and continuing with advanced level modern approaches, we review the vast number of possibilities for controlling metabolic fluxes. Our aim is to give a brief and informative insight about commonly used tools and universalized methodologies for metabolic pathway balancing and optimization.

Development of a Recombinant Escherichia coli Strain for Overproduction of the Plant Pigment Anthocyanin

“…Similar to lycopene, C3G in the colorimetric assay can be used as a screening molecule for desirable phenotypes in applications such as combinatorial engineering (37,38). The calibration curve generated could be utilized for rapid C3G concentration quantification without the need for complex and timeconsuming analytical tools.…”

Integrated analysis of isopentenyl pyrophosphate (IPP) toxicity in isoprenoid-producing Escherichia coli

“…The production of a toxic intermediate can lead to heterologous pathway "breakage" through regulatory feedback or the selection of mutations that attenuate pathway flux and thus reduce toxicity (Jones et al, 2015). In strain 3Amk, the rapid decrease in peak IPP levels and associated growth recovery suggested that breakage might have occurred, although the continued production of isoprenol implied that the heterologous pathway was at least partially functional.…”

“…Although natural metabolic pathways have evolved intricate regulation to prevent the buildup of toxic metabolites, heterologous pathways, which frequently consist of non-native reactions from different organisms, typically lack such sophistication (Chubukov et al, 2016). Without regulation, imbalances in assembled pathways frequently lead to metabolite accumulation and toxicity (Jones et al, 2015). Typical metabolic engineering and synthetic biology workflows for improved pathway expression (Boyle and Silver, 2012;Jullesson et al, 2015;Keasling, 2012) may amplify this issue by causing massive fluctuations in metabolite concentrations.…”

Overcoming heterologous protein interdependency to optimize P450-mediated Taxol precursor synthesis in Escherichia coli

“…Although much attention has been given to developing "parts" that control molecular processes like transcription and translation (7)(8)(9), little has been focused on developing different classes of metabolic chemistries (i.e., polymerization, cyclization, oxygenation, and glycosylation) as potential parts. Systematizing the optimization of different metabolic chemistries would bring us closer to an "off the shelf" catalyst approach in metabolic engineering, which would greatly benefit the synthesis of complex molecules such as the blockbuster anticancer agent Taxol.…”