Optimized co-fermentation strategy for efficient production of Dihydro-β-ionone from β-Ionol using engineered...

Dihydro-β-ionone is a high-value volatile compound widely used in fragrances, cosmetics, and food-related applications, driving growing interest in its sustainable biosynthesis. In this study, we developed and optimized a modular co-culture system comprising Escherichia coli and Saccharomyces cerevisiae to biosynthesize dihydro-β-ionone from β-ionol. The E. coli module, expressing short-chain dehydrogenase NaSDR and glucose dehydrogenase (GDH) for NADP⁺/NADPH recycling, efficiently oxidized β-ionol to β-ionone under optimized conditions (LB medium, 0.2 mM IPTG, 30 °C), producing 884.62 mg/L β-ionone with a conversion efficiency of 44.2 %. Subsequently, S. cerevisiae module expressing double bond reductase AaDBR1, supported by endogenous NADPH-regeneration enzyme Pos5p, reduced β-ionone to dihydro-β-ionone. Optimal performance was achieved when S. cerevisiae was added 24 h after the start of E. coli fermentation at an inoculation density of OD₆₀₀ = 240. This configuration yielded 829.71 mg/L dihydro-β-ionone at a conversion efficiency of 41.45 %. By decoupling oxidation and reduction steps across two microbial hosts, this work provides technical support for more efficient microbial production of dihydro-β-ionone and its derivatives, with potential applications in industrial biotechnology.