Lysine acetylation is a common post-translational modification in bacteria, but the mechanisms regulating this process and its link to metabolism are poorly understood. Weinert et al. now show that growth arrest results in a global, low-level increase in acetylation in Escherichia coli owing to the accumulation of acetyl phosphate (AcP), an intermediary metabolite of glycolysis. This effect was shown to be independent of YfiQ, the only known acetyltransferase in E. coli, suggesting that AcP donates its acetyl group in a non-enzymatic manner. Indeed, AcP was shown to chemically acetylate lysine residues in vitro, and AcP levels correlated with acetylation levels in vivo. Furthermore, the indiscriminate acetylation pattern that was observed is inconsistent with site-specific mechanisms that are typical of enzyme-catalysed reactions. However, future work is needed to rule out the potential involvement of an unknown acetyltransferase and to understand the functional consequences of such widespread acetylation.