Aniline Biosynthesis and the Archival of EC 4.1.1.24.

Aniline is an essential synthetic building block, with its manufacture reliant on fossil carbon feedstocks. While bioproduction could connect aniline manufacture to renewable carbon inputs, efficient metabolic pathway design remains a hurdle for aniline biosynthesis. Two alternate pathways were examined, involving the promiscuous activity of either non-oxidative phenolic acid decarboxylases or tyrosine phenol-lyases (TPLs) on an amine substrate. The decarboxylases exhibited <1% aniline yields under oxygen-scarce conditions, whereas no candidate TPLs produced aniline. Further optimization of the decarboxylase reaction is necessary to construct a viable, fully biosynthetic route towards aniline. Incidentally, we observed that (1) aniline reacts abiotically with glucose in culture medium, and (2) the existing literature on aniline biosynthesis heavily references the EC 4.1.1.24 aminobenzoate decarboxylase classification, which has not been validated since first proposed almost seventy years ago. We recommend the EC 4.1.1.24 entry be archived, supporting the EC 4.1.1.61 phenolic acid decarboxylase entry instead.