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.

Trichoderma atroviride IMI 206040 synthesizes the coconut lactone 6-pentyl-α-pyrone (6-PAP) de novo and Aspergillus niger DSM 821 produces the rose-like flavour compound 2-phenylethanol (2-PE) from the precursor l-phenylalanine. Here, microparticles of different chemical composition and nominal particle diameter in the range 5-250 µm were added to shake-flask cultures of both fungi to investigate the particles' effect on product formation. Maximum 2-PE concentration increased by a factor of 1.3 to 1430 mg/l with the addition of 2% w/v talc (40 µm diameter). Maximum 6-PAP concentration increased by a factor of 2 to 40 mg/l with the addition of 2% w/v iron (II, III) oxide. The influence of ions leaching out of the particles was investigated by cultivating the fungi in leached particle medium. For the first time, the positive effect of the microparticle-enhanced cultivation (MPEC) technique on the microbial production of volatile metabolites, here flavour compounds from submerged fungal cultures, is demonstrated. The effect is strain- and particle-specific.

We show that CO 2 can be converted by an engineered "Knallgas" bacterium (Cupriavidus necator) into the terpene a-humulene.H eterologous expression of the mevalonate pathwaya nd a-humulene synthase resulted in the production of approximately 10 mg a-humulene per gram cell dry mass (CDW) under heterotrophic conditions.T his first example of chemolithoautotrophic production of at erpene from carbon dioxide,h ydrogen, and oxygen is ap romising starting point for the production of different high-value terpene compounds from abundant and simple raw materials.F urthermore,the production system was used to produce 17 mg ahumulene per gram CDWf rom CO 2 and electrical energy in microbial electrosynthesis (MES) mode.Given that the system can convert CO 2 by using electrical energy from solar energy,it opens anew route to artificial photosynthetic systems.

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