Advance in L-malate production based on metabolic engineering strategies

L-Malate was widely used in food, pharmaceutical and chemical industries. It was industrially produced using chemical or enzymatic method with petroleum derived resource as substrate. With reduction in oil resources, interest in the production of L-malate by microbial fermentation had been renewed. In recent years, metabolic engineering strategies have been applied to achieve L-malate production in Escherichia coli and yeasts etc., which showed certain application prospect. Meanwhile, L-malate synthesis by constructing metabolic pathways in vitro with synthetic metabolic engineering had high theoretical value. This paper summarized metabolic routes for L-malate synthesis in microorganisms. Thereafter, metabolic engineering strategies for L-malate production including enhancement of L-malate synthesis pathway, deletion of byproduct accumulation routes and improvement of redox-power regeneration were reviewed to systemically explain the progress in metabolic mechanism of L- malate. Finally, further research areas in metabolically engineered L- malate production were proposed.