Modification of Yarrowia lipolytica for the biosynthesis of canthaxanthin by metabolic engineering
Canthaxanthin,an orange-red ketocarotenoid,is widely used as a colorant and antioxidant in food,feed,and cosmetic industries.In order to produce high levels of canthaxanthin,Yarrowia lipolytica was modified to construct a high β-carotene-producing strain achieved by enhancing the flux of endogenous ger-anylgeranyl diphosphate,strengthening the exogenous β-carotene biosynthetic pathway,overexpressing the DNA repair gene rad52,and enhancing NADPH supply and precursors.The study further introduced a β-carotene ketolase gene from Paracoccus sp.,increased gene copy number and the supply of β-carotene pre-cursors,and complemented auxotrophic markers.The final engineered strain synthesized 301.1 mg/L of canthaxanthin under shake-flask fermentation conditions.The results of the experiment were reported the highest shake-flask production of canthaxanthin by microorganisms to date,providing theoretical guidance for the commercial production of canthaxanthin and serving as a reference for the synthesis of other carote-noids.