Adaptive Expansion of Biodegradation by Pseudomonas Putida F1

Abstract

Pseudomonas putida F1 (PpF1) catabolizes aromatic compounds via benzoate dioxygenase, phenylacetyl-CoA epoxidase, p-cymene-monooxygenase, and toluene dioxygenase-mediated pathways, and the latter is shown here to be highly flexible, supporting growth on previously untested aromatic alkenes, esters, amides, alcohols, amines, and multi-ring compounds. P. putida F1 is a highly studied model aromatic hydrocarbon oxidizer that grows on relatively few mono-substituted benzenes despite its genome encoding a toluene dioxygenase enzyme that oxidizes more than 150 compounds. While toluene dioxygenase and toluene dihydrodiol dehydrogenase oxidize many mono-substituted benzene ring compounds, further enzymatic processing may be inhibited, leading to accumulation of the respective catechol or 2-hydroxy-6-oxo-2,4-dienoate intermediate. The present study demonstrated that P. putida F1 can undergo adaption leading to a more expanded growth range of mono-substituted benzene ring compounds than had been previously demonstrated. Studies with well-characterized mutant derivatives of P. putida F1 and growth on expected metabolites of the toluene dioxygenase pathway indicated that the newly described metabolism was dependent on the Tod pathway enzymes. This study also revealed the interplay between the Tod pathway enzymes and catabolism of the aromatic acids liberated by TodF. TodABCDEF processing of allylbenzene and 1-phenylethanol liberates 3-butenoic acid and lactic acid, respectively, both of which support growth of P. putida F1.