Vol 34(2018) N 2 p. 18-25; DOI 10.21519/0234-2758-2018-34-2-18-25
A.Yu. Skorokhodova*, A.Yu. Gulevich, and V.G. Debabov

Inactivation of Malic Enzymes Improves Anaerobic Production of Four-Carbon Dicarboxylic Acids by Recombinant Escherichia coli Strains Expressing Pyruvate Carboxylase

The State Research Institute for Genetics and Selection of Industrial Microorganisms of National Research Center "Kurchatov Institute ", 117545, Moscow, Russia

Received - 04.12.2017; Accepted - 12.12.2017


The genes maeA and maeB encoding NADH- and NADPH-dependent malic enzymes have been deleted in a recombinant Escherichia coli strain with the inactivated mixed-acid fermentation pathways and a modified system of glucose transport and phosphorylation upon the heterological expression of the pyruvate carboxylase gene. During anaerobic glucose utilization, the parental strain synthesized malic, fumaric, and succinic acids as the main fermentation end products, while pyruvic acid was accumulated as the main by-product resulting from the functioning of the pyruvate-oxaloacetate-malate-pyruvate futile cycle. Upon individual deletions of the maeA and maeB genes, the mutant strains converted glucose into four-carbon dicarboxylic acids with the increased efficiency still secreting notable amounts of pyruvic acid. The combined inactivation of both malic enzymes in the constructed strain significantly elevated the portion of malic, fumaric, and succinic acids among the fermentation end products with the concomitant decrease in the secretion of pyruvic acid and other by-products due to the abolishment of the action of the futile cycle competing with the target biosynthetic processes.

Escherichia coli, glucose, fermentation, malic enzyme, metabolic engineering, pyruvate carboxylase, fumaric acid, malic acid, succinic acid.

Acknowledgements-The work was financially supported by the Russian Science Foundation (Project 16-14-10389).