초록
<P>Microbial electrosynthesis is potentially a sustainable biotechnology for the conversion of the greenhouse gas CO<SUB>2</SUB> into carboxylic acids, thus far mostly limited to acetic acid (C2). Despite the environmental benefits of recycling CO<SUB>2</SUB> emissions to counter global warming, bioelectrochemical production of acetate is not very attractive from an economic point of view. Conversely, carboxylates and corresponding alcohols with longer C content not only have a higher economical value as compared to acetate, but they are also relevant platform chemicals and fuels used on a diverse array of industrial applications. Here, we report on a specific mixed reactor microbiome capable of producing a mixture of C4 and C6 carboxylic acids (isobutyric, <I>n</I>-butyric, and <I>n</I>-caproic acids) and their corresponding alcohols (isobutanol, <I>n</I>-butanol, and <I>n</I>-hexanol) using CO<SUB>2</SUB> as the sole carbon source and reducing power provided by an electrode. Metagenomic analysis supports the hypothesis of a sequential carbon chain elongation process comprised of acetogenesis, solventogenesis, and reverse β-oxidation, and that isobutyric acid is derived from the isomerization of <I>n</I>-butyric acid.</P><P>Supply of electrical energy to a mixed reactor microbiome enabled a sustainable production of C4 and C6 commodity chemicals and biofuels from carbon dioxide.</P><BR>[FIG OMISSION]</BR>