Engineering Modification for the Efficient Synthesis of β-ionone by Yarrowia lipolytica

β-Ionone, prized for its characteristic violet aroma and woody undertones, has emerged as a valuable ingredient in the fragrance industry. Beyond its aromatic qualities, growing interest in its diverse biological activities has positioned it as a compound of relevance in the biopharmaceutical field. As production strategies shift from traditional chemical synthesis toward more sustainable biological routes, this study explores the engineered biosynthesis of β-ionone in Yarrowia lipolytica. Through systematic combinatorial metabolic engineering, a strain capable of accumulating 743 mg/L of β-carotene was constructed. Heterologous expression of the petunia-derived carotenoid cleavage dioxygenase gene PhCCD1 enabled efficient conversion of β-carotene to β-ionone, yielding 137 mg/L in shake-flask cultures. Subsequent integration of the isoprene alcohol metabolic pathway further enhanced precursor supply, boosting β-ionone production to 236.7 mg/L in shake flasks. In a 5 L bioreactor, optimization of the culture medium and feeding strategy led to a final titer of 624.7 mg/L. Collectively, these results establish a promising and replicable strategy for developing microbial cell factories capable of efficient β-ionone synthesis.