Gram‐scale production of the sesquiterpene α‐humulene with Cupriavidus necator

Abstract Terpenoids have an impressive structural diversity and provide valuable substances for a variety of industrial applications. Among terpenes, the sesquiterpenes (C 15 ) are the largest subclass with bioactivities ranging from aroma to health promotion. In this article, we show a gram‐scale production of the sesquiterpene α‐humulene in final aqueous concentrations of 2 g L −1 with the recombinant strain Cupriavidus necator pKR‐hum in a fed‐batch mode on fructose as carbon source and n‐dodecane as an extracting organic phase for in situ product removal. Since C. necator is capable of both heterotrophic and autotrophic growth, we additionally modeled the theoretically possible yields of a heterotrophic versus an autotrophic process on CO 2 in industrially relevant quantities. We compared the cost‐effectiveness of both processes based on a production of 10 t α‐humulene per year, with both processes performing equally with similar costs and gains. Furthermore, the expression and activity of 3‐hydroxymethylglutaryl‐CoA reductase ( hmgR ) from Myxococcus xanthus was identified as the main limitation of our constructed C. necator pKR‐hum strain. Thus, we outlined possible solutions for further improvement of our production strain, for example, the replacement of the hmgR from M. xanthus by a plant‐based variant to increase α‐humulene production titers in the future.