CATECHOL DIOXYGENASE EXPRESSION IN A PSEUDOMONAS-FLUORESCENS STRAIN EXPOSED TO DIFFERENT AROMATIC-COMPOUNDS

Batch cultures of Pseudomonas fluorescens (strain P2a) maintained unde r carbon-limiting conditions in the presence of chrysene and other aro matics, survived starvation with no detectable changes in cell number for at least 4 months. P2a also demonstrated high dioxygenase levels a fter growth on benzoate and catechol. To characterize this strain furt her, early stationary-phase cells were resuspended in fresh mineral me dium containing different aromatics, to evaluate enzyme expression in the presence of high-molecular-mass (isocyclic and heterocyclic) compo unds. Results demonstrated effects on catechol 1,2-dioxygenase modulat ion by the model compounds used, confirming a low substrate specificit y for this enzyme. The increases of specific activity observed in the presence of heterocyclic compounds were higher than those observed wit h isocyclic compounds.