Constructing Haloarchaeal MVA Pathway in <i>Serratia marcescens</i> for Synthesis of Ocimene

Ocimene, a valuable monoterpene with applications in agriculture, pharmaceuticals, and fragrances, is challenging to produce at high yields using traditional microbial platforms such as Escherichia coli and Saccharomyces cerevisiae due to monoterpene toxicity. In this study, Serratia marcescens, known for its tolerance to organic solvents and terpenes, was engineered to synthesize ocimene through the haloarchaeal mevalonate (MVA) pathway. We optimized key enzymes, promoters, and pathway construction to enhance production. The engineered strain successfully produced ocimene, with a yield of 436 mg·L^-1 in a 50 mL shake-flask and 2.4 g·L^-1 in a 5 L fermenter, demonstrating the potential of S. marcescens as an efficient platform for industrial-scale ocimene production.