Genetic Engineering of Escherichia coli W for Linalool Production Using Beet Juice as the Sole Carbon Source

Linalool is a high-value monoterpene alcohol widely used in the fragrance, flavor, pharmaceutical industries, as well as a component of jet fuel. However, conventional extraction from linalool-producing plants faces the challenges of costly, low productivity and sustainability. In this study, Escherichia coli W (ATCC 9637) was genetically engineered with plasmids pZR808, pZR1464 to enable linalool biosynthesis using beet juice-derived sucrose as the sole carbon source. The expression of linalool synthase (LinS) in genetically engineered E. coli W was confirmed by Western blot. GC-MS analysis confirmed linalool production. Continuous linalool production by E. coli W (pZR1464) accumulated to 141.6 µmols of linalool within 72 h. Among the engineered strains, the pZR1464 strain, carrying both the LinS gene and the DXP operon, achieved the highest linalool yield of 50 mg L− 1. Day− 1. OD600− 1. Approximately 3–10 times greater yields than strain pZR808 bearing only the LinS. Sucrose utilization analysis indicated that E. coli consumed approximately 1.44 mmol of sucrose in the first 24 h, primarily for biomass production. Conversion efficiency of sucrose to linalool significantly improved over time. It increased from 27.28 µmols of linalool mol− 1 sucrose (within 24 h) to 94.34 µmols of linalool mol− 1 sucrose within 48 h, demonstrating metabolic adaptability. The engineered strain exhibited stable growth kinetics without adverse effects, positioning strain pZR1464 as a promising candidate for sustainable linalool production. Future selection of more powerful LinS genes combined with introduction of an exogenous mevalonate (MVA) pathway, could boost the yields by more than 300-fold, leading to commercially viable production of linalool using beet juice as the sole carbon source.