Biocatalytic synthesis of monocyclic arene-dihydrodiols and -diols by Escherichia coli cells expressing hybrid toluene/biphenyl dioxygenase and dihydrodiol dehydrogenase genes

The hybrid toluene/biphenyl dioxygenase, which is encoded by the todC1 gene of Pseudomonas putida F1 and the bphA2A3A4 genes of Pseudomonas pseudoalcaligenes KF707, has substrate ranges wider than toluene dioxygenase endoced by the todC1C2BA genes of P. putida F1. We carried out growing cell reactions by Escherichia coli expressing the todC1-bphA2A3A4 genes for the comprehensive production of monocyclic arene-dihydrodiols. As a result, we successfully biotranformed acetophenone-related compounds (acetophenone, propiophenone, and butyrophenone) to the corresponding cis-dihydrodiols. Furthermore, we performed the bioconversion experiments by E. coli cells expressing the bphB (dihydrodiol dehydrogenase) gene in addition to todC1-bphA2A3A4 to produce a series of monocyclic arene-diols. Consequently, toluene, benzene, stylene, p-xylene, acetophenone, propiophenone, butyrophenone, and trifluoroacetophenone were converted to the corresponding vicinal diols. The antioxidative activity of these generated diol compounds was markedly higher than that of the substrate used.