Growth phase dependent substrate utilization by Pseudomonas strain PH1.
Pseudomonas strain PH1 can utilize nitro-, chloro-, and aminophenols and has been used in this study. The enzymes of the two-pathway viz., phenol, and meta-aminophenol (MAP) were analyzed under different growth conditions. The enzymes responsible for phenol to catechol conversion followed by the ring cleavage enzyme for catechol; and also the enzymes responsible for MAP oxidation and hydroxylation of resorcinol, were studied. Enzyme and respirometric assays were carried out with cells harvested from log phase and stationary phase from medium with different carbon sources and nitrogen levels. It was observed that the first step for utilization of both the substrates requires the same physiological state of the cells; whereas, the subsequent step follows independent approach to intermediates, based on cellular physiology.