Modulation of major components of bergamot essential oil in Escherichia coli through metabolic engineering strategies

Bergamot essential oil has rich biological activity and is commonly applied in fragrance, cosmetics and daily chemical products. However, the entire production process of bergamot fruit from cultivation to extraction of essential oil is inefficient and unstable, cannot meet the growing market demand. To overcome this limitation, we first established a highly efficient biosynthetic platform for production of the major components ((+)-limonene and (-)-linalool) of bergamot essential oil. By increasing the supply of monoterpene precursors and screening for the direct precursors NPP and GPP, a biosynthetic pathway capable of producing both (+)-limonene and (-)-linalool was constructed in Escherichia coli . Then, by screening and mutating the linalool synthase and modifying the limonene synthase by fusion proteins , the obtained strain BW4M42 can produce 277.8 mg/L (+)-limonene and 54.2 mg/L (-)-linalool in shake flasks after optimizing the fermentation culture conditions. In a 1.3-L reactor, the total concentration reached 2688.2 mg/L, including 2010.2 mg/L (+)-limonene and 678 mg/L (-)-linalool. The (-)-linalool/(+)-limonene ratio produced by the strain BW4M42 meets the ISO 3520:2022 standard for bergamot essential oil. This study provides the possibility to construct a biosynthetic platform for producing the major components of plant essential oils through metabolic engineering .