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

Abstract

We show that CO can be converted by an engineered "Knallgas" bacterium (Cupriavidus necator) into the terpene α-humulene. Heterologous expression of the mevalonate pathway and α-humulene synthase resulted in the production of approximately 10 mg α-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 α-humulene per gram CDW from CO and electrical energy in microbial electrosynthesis (MES) mode. Given that the system can convert CO by using electrical energy from solar energy, it opens a new route to artificial photosynthetic systems.

Water Splitting–Biosynthetic Hybrid System for CO2 Conversion using Nickel Nanoparticles Embedded in N‐Doped Carbon Nanotubes

“…[6][7][8][9] Nevertheless, severalc hallenges still must be overcome, such as (1) low value of CRR products,( 2) low products selectivity,a nd (3) low energy efficiency. [12][13][14][15][16] Yang et al employed a-NiS as an electrocatalyst for the hydrogen evolution reaction( HER) and Methanosarcina barkeri as ab iocatalyst to realize CO 2 to CH 4 conversion with a low overpotential (360 mV) and high faradaic efficiency (FE, up to 86 %). Inspired by some autotrophic microorganisms (e.g., Sporomusa ovata and Ralstoniae utropha)c apable of converting CO 2 to organic compounds[ i.e.,a cetate, poly-b-hydroxybutyrate (PHB), isopropanol, and alpha-humulene],h ybrid bio-inorganic systemsc ombining water splitting with H 2 -oxidizing autotrophic biosynthesish ave been developed for efficient CO 2 conversion.…”

Hydrogen‐Mediated Electron Transfer in Hybrid Microbial–Inorganic Systems and Application in Energy and the Environment

“…With different metabolic routes involved, a hydrogen‐mediated hybrid system is able to fix CO 2 in a variety of value‐added products, which are not attainable via traditional abiotic CO 2 reduction systems. Some researchers have successfully utilized hydrogen‐mediated hybrid microbial–inorganic systems to efficiently convert CO 2 into high‐value‐added chemicals, such as fuels,[13a] organic acids, polymers, and pharmaceuticals . It provides an attractive strategy to reduce CO 2 emissions and simultaneously generate value‐added chemicals.…”

“…Another successful example used an engineered strain of R. eutropha to produce 17 mg α‐humulene per gram cell dry mass from CO 2 fixation in a hybrid microbial–inorganic system. α‐humulene is a high‐value‐added terpene …”

Response‐Surface‐Optimized and Scaled‐Up Microbial Electrosynthesis of Chiral Alcohols

“…Electrobiotechnology constitutes a platform for Power‐to‐Chemicals, which stores inexpensive/excess electrical energy in chemical bonds by combining electrochemistry and biotechnology and offers a plethora of applications . Among these, microbial electrosynthesis (MES) that uses microorganisms as bio(electro)catalysts targets the production of fine and bulk chemicals as demonstrated for, for example, acetic acid, 1,3‐propanediol, and α‐humulene . Recently, we described a universal chassis for the enantioselective MES of chiral alcohols from cheap ketones by using resting Escherichia coli whole‐cell biocatalysts (Figure ) …”