Optimal microbial adaptation routes for the rapid degradation of high concentration of phenol

Pseudomonas fluorescence KNU417 was able to degrade up to 700 mg/L of phenol in 65 h but could not degrade 1,000 mg/L of phenol. Phenol degradation rate was noticeably enhanced by pre-adaptation. In addition, the cell was able to degrade up to 1,300 mg/L of phenol by pre-adapting to 700 mg/L of phenol. Repeated adaptations to the same concentration of phenol showed negligible increase in degradation rate. Also, relatively low concentration of phenol (100-700 mg/L) required only one pre-adaptation while high concentration (1,000 mg/L) did two consecutive stepwise pre-adaptations for rapid degradation. Optimal adaptation routes were suggested for the fast phenol degradation. For example, 1,000 mg/L of phenol was degraded as fast as in 48 h when the cell was pre-adapted to 100 and 300 mg/L of phenol sequentially. The mechanism of adaptation was explained in terms of catechol 1,2-dioxygenase induction, related to aromatic ring cleavage.