CO2 to Terpenes: Autotrophic and Electroautotrophic α-Humulene Production with Cupriavidus necator

We show that CO2 can be converted by an engineered Knallgas bacterium (Cupriavidus necator) into the terpene alpha-humulene. Heterologous expression of the mevalonate pathway and alpha-humulene synthase resulted in the production of approximately 10 mg alpha-humulene per gram cell dry mass (CDW) under heterotrophic conditions. This first example of chemolithoautotrophic production of a terpene from carbon dioxide, hydrogen, and oxygen is a promising starting point for the production of different high-value terpene compounds from abundant and simple raw materials. Furthermore, the production system was used to produce 17 mg alpha-humulene per gram CDW from CO2 and electrical energy in microbial electrosynthesis (MES) mode. Given that the system can convert CO2 by using electrical energy from solar energy, it opens a new route to artificial photosynthetic systems.