Pseudomonas putida Mutants Defective in the Metabolism of the Products of meta Fission of Catechol and Its Methyl Analogues

Abstract

A selection procedure is described which was used to isolate mutants of Pseudomonas putida strain U in the following enzymes of the meta -fission pathway of phenol and cresols: hydrolase, tautomerase, and decarboxylase. Strains deficient in the hydrolase are unable to use either o - or m -cresol as a sole carbon source and were shown to accumulate 2-hydroxy-6-keto-2,4-heptadienoate when incubated in the presence of o - or m -cresol. When 2-hydroxymuconic semialdehyde (plus nicotinamide adenine dinucleotide, oxidized form) was metabolized by phenol-induced extracts of tautomerase-deficient strains, the enol tautomer of 4-oxalocrotonate accumulated and was then converted slowly to the keto tautomer by a nonenzymatic reaction. Phenol-induced extracts of decarboxylase-deficient strains accumulated the keto tautomer of 4-oxalocrotonate from 2-hydroxymuconic semialdehyde (plus nicotinamide adenine dinucleotide, oxidized form). Strains with an inactive decarboxylase are unable to completely metabolize either phenol or p -cresol. Tautomerase-defective strains are unable to grow with p -cresol as the sole carbon source and grow only very slowly on phenol.