Transient Accumulation of Metabolic Intermediates of p-Cresol in the Culture Medium by a Pseudomonas sp. Strain A Isolated from a Sewage Treatment Plant

Abstract

Activated sludge from a sewage treatment plant in Kanpur, India, was screened for bacterial strains metabolizing p-cresol exclusively under aerobic conditions. One such isolate was identified to be belonging to the genus Pseudomonas based on morphological and physiological criteria as well as 16S ribosomal RNA gene sequence analysis. Two intermediates were identified from the culture medium during the growth phase of Pseudomonas sp. strain A that indicated that the strain degraded p-cresol via the protocatechuate (PCA) pathway. p-Cresol was rapidly converted into p-hydroxybenzaldehyde (PHB) during early growth phase, which was later utilized after p-cresol depletion. p-Hydroxybenzoate (PHBA) accumulation was observed during the later stages of exponential growth phase. Kinetic constants for the degradation of p-cresol were determined using Haldane’s model. High μmax and inhibitory constant (K I) values along with the observed accumulation of significant amounts of PHB in culture filtrates seem to indicate that the isolated Pseudomonas sp. strain A may be of potential use in biotransformations.