Figure 4. Volatile sesquiterpene production by E. coli cultures expressing Stehi1|25180, Stehi1|64702 and Stehi1|73029.
The headspace of E. coli cultures expressing A) Stehi1|25180, B) Stehi1|64702 and C) Stehi1|73029 was sampled and analyzed for production of sesquiterpenes by GC/MS. The major product of cells expressing Stehi1|25180, Stehi1|64702 and Stehi1|73029 is Δ-6 protoilludene 7, a 1,11-cyclization of (2E,6E)-FPP. The minor peak observed for Stehi1|64702 and Stehi1|73029 was identified as β-elemene 8, which results from a 1,10-cyclization of (2E,6E)-FPP. Indole (labeled with an asterisk *), a breakdown product of tryptophan, is naturally produced by E. coli and serves as an internal standard.