Enhanced production of δ-guaiene, a bicyclic sesquiterpene accumulated in agarwood, by coexpression of δ-guaiene synthase and farnesyl diphosphate synthase genes in Escherichia coli

Two genes involved in δ-guaiene biosynthesis in Aquilaria microcarpa, δ-guaiene synthase (GS) and farnesyl diphosphate synthase (FPS), were overexpressed in Escherichia coli cells. Immunoblot analysis revealed that the concentration of GS-translated protein was rather low in the cells transformed by solely GS while appreciable accumulation of the recombinant protein was observed when GS was coexpressed with FPS. GS-transformed cells liberated only a trace amount of δ-guaiene (0.004 δg/mL culture), however, the concentration of the compound elevated to 0.08 δg/mL culture in the cells transformed by GS plus FPS. δ-Guaiene biosynthesis was markedly activated when E. coli cells coexpressing GS and FPS were incubated in enriched Terrific broth, and the content of the compound increased to approximately 0.6 δg/mL culture. These results suggest that coexpression of FPS and GS in E. coli is required for efficient δ-guaiene production in the bacterial cells, and the sesquiterpene-producing activity of the transformant is appreciably enhanced in the nutrients-enriched medium.