Advances in microbial heterologous production of flavonoids

Flavonoids are important plant specific secondary metabolites that are synthesized from the general phenylpropanoid pathway and have many pharmaceutical and nutraceutical functions. Separation of pure flavonoids from plants material is very difficult and chemical syntheses of flavonoids require extreme reaction conditions and toxic chemicals. However, in the past decades, engineered microbes are becoming increasingly important as recombinant production platforms. Cultivation of the recombinant strains in rich medium offers another choice for the production of flavonoids. In the present review, we cover the main achievements that the multi-gene pathway of phenylpropanoid is introduced as microorganisms to heterologously produce flavonoids, analyze the key factors affecting heterologous production of flavonoids in microbes, and discuss the new research prospect.   Key words: Flavonoids, metabolic engineering, natural products, synthetic biology.