Articles of Significant Interest Selected from This Issue by the Editors

Comparably inert substrates, such as ketones, phenols, or some aromatic hydrocarbons, are activated in the absence of molecular oxygen by energy-expensive carboxylation reactions. Acosta et al. (p. 6228 – 6235) determined that the sulfate-reducing bacterium Desulfococcus biacutus activates acetone by a carbonylation reaction with carbon monoxide as cosubstrate, thus forming a reactive aldehyde derivative at a comparably low level of ATP expenditure. To date, carbon monoxide was known as a cosubstrate only in the well-described carbon monoxide dehydrogenase/acetyl coenzyme A (acetyl-CoA) synthase reaction, the key enzyme of homoacetogenic bacteria. This novel metabolic concept may be applicable also for anaerobic activation of other comparably inert substrates.