[Metabolic engineering of Yarrowia lipolytica for astaxanthin production]

Astaxanthin, a high-value terpenoid secondary metabolite that exhibits excellent antioxidant activity, has broad application potential in the pharmaceutical and nutraceutical industries. However, its sophisticated biosynthetic pathway poses a great challenge for efficient production and industrial-scale application of astaxanthin. In this study, the unconventional oleaginous yeast Yarrowia lipolytica was employed as the chassis organism, and a multidimensional metabolic engineering strategy combined with fermentation process optimization was used to construct a microbial cell factory for astaxanthin production. Firstly, a heterologous β-carotene biosynthetic pathway was reconstituted, the carbon flux supply of the mevalonate (MVA) pathway was systematically enhanced, and endogenous branch metabolism was blocked, leading to the initial construction of an astaxanthin-producing strain. Subsequently, a RIDD-RIAD protein interaction tag was introduced to optimize the expression patterns of the key rate-limiting enzymes of β-carotene ketolase (CrtW) and β-carotene hydroxylase (CrtZ), thereby effectively improving the efficiency of astaxanthin biosynthesis. Following this, six rounds of iterative targeted metabolic modification combined with shake-flask fermentation significantly enhanced the biosynthetic potential of the engineered strains. The results showed that the engineered strain YAX11 achieved an astaxanthin titer of 107.4 mg/L in shake-flask fermentation, and the titer was increased to 1 148.4 mg/L in a 5 L bioreactor. Through the deep integration of metabolic network remodeling and fermentation process optimization, this study successfully constructed a Y. lipolytica cell factory for astaxanthin production, providing a theoretical reference for the green and large-scale manufacturing of astaxanthin, as well as metabolic engineering strategies for the heterologous synthesis of other terpenoid compounds.