Establishing a Microbial Platform for Aromatic Lactones Production From Glucose

Aromatic lactones, including Homogentisate-γ-lactone, 2-coumaronone, and coumarin, have broad applications in pharmaceuticals and agrochemicals, due to their antimicrobial, anti-inflammatory, and antioxidant activities. However, their industrial production relies on multistep chemical synthesis or plant extraction, which suffer from harsh reaction conditions, low efficiency, and limited sustainability. The absence of complete biosynthetic pathways and key functional enzymes further hampers microbial production of these compounds. Here, we report the design of artificial biosynthetic routes for aromatic lactone production in Escherichia coli. Through systematic screening of hydroxylases and identification and engineering of carboxylic acid reductase Car variants enabling lactonization of hydroxylated intermediates, combined with metabolic engineering of precursor supply and cofactor availability, we achieved de novo biosynthesis of 2-coumaronone from glucose. In addition, we developed a chemo-enzymatic strategy enabling the production of homogentisate-γ-lactone from glucose via biosynthesized intermediates, followed by acid-catalyzed lactonization. This work establishes an attractive microbial platform for aromatic lactone production, providing a generalizable framework for the sustainable microbial synthesis of high-value lactone compounds.