Developing <i>Ogataea parapolymorpha</i> as a Novel Platform for β-Carotene Production via Global Metabolic Engineering

β-Carotene is a fat-soluble terpenoid substance that is often used as a food additive. The use of microbial cell factories to synthesize β-carotene is a promising alternative to plant extraction methods. <i>Ogataea parapolymorpha</i> is a nonconventional yeast with thermotolerance, a broad substrate spectrum, and high-density fermentation, making it an excellent host for the biological production of β-carotene. Accordingly, we applied global metabolic engineering to <i>O. parapolymorpha</i>. First, a β-carotene biosynthetic pathway was constructed by screening and identifying the enzymes involved in its synthesis. Subsequently, β-carotene was produced by optimizing the mevalonate pathway and increasing the supply of precursor acetyl-CoA and cofactor NADPH. Finally, competing pathways were downregulated to increase β-carotene production. Our strategy culminated in a β-carotene titer of 3861.21 mg/L during fed-batch fermentation in a 5-L bioreactor. This study provides an alternative platform for the biosynthesis of carotenoids.