Designing and Constructing a Novel Artificial Pathway for Malonic Acid Production Biologically.

Shuying Gu,Jingen Li,Chaoguang Tian,Yonghong Yao,Zhen Zhao

doi:10.3389/fbioe.2021.820507

Abstract

Malonic acid is used as a common component of many products and processes in the pharmaceutical and cosmetic industries. Here, we designed a novel artificial synthetic pathway of malonic acid, in which oxaloacetate, an intermediate of cytoplasmic reductive tricarboxylic acid (rTCA) pathway, is converted to malonic semialdehyde and then to malonic acid, sequentially catalyzed by a-keto decarboxylase and malonic semialdehyde dehydrogenase. After the systematic screening, we discovered the enzyme oxaloacetate decarboxylase Mdc, catalyzing the first step of the artificially designed pathway in vitro. Then, this synthetic pathway was functionally constructed in cellulolytic thermophilic fungus Myceliophthora thermophila. After enhancement of glucose uptake, the titer of malonic acid achieved 42.5 mg/L. This study presents a novel biological pathway for producing malonic acid from renewable resources in the future.

Highlights

Malonic acid, formally known as propanedioic acid, is widely used in manufacturing processes, such as the petrochemical, pharmaceutical, and cosmetic industries
oxaloacetic acid (OAA) is converted to malonic semialdehyde (MSA) by a-keto decarboxylase (Kdc) and to malonic acid (Figure 1A)
Kdc is the crucial enzyme step required to divert flux from OAA to malonic acid, which is widespread in plants, yeasts, and fungi

Summary

Introduction

Formally known as propanedioic acid, is widely used in manufacturing processes, such as the petrochemical, pharmaceutical, and cosmetic industries. Two non-natural metabolic pathways have been sought and introduced into microbes, using malonic semialdehyde (MSA) or malonyl-CoA as the precursor (Table 1) (Song et al, 2016; Dietrich et al, 2017; Chae et al, 2020). Succinate semialdehyde dehydrogenase encoded by E. coli yneI was used to catalyze the reaction of MSA to malic acid, and the titer of malonic acid reached 3.60 g/L by fed-batch fermentation (Song et al, 2016).

Methods

Results

Conclusion