Assessment of the kinetics of phenol bioconversion by Pseudomonas sp. OX1

The present contribution reports on the characterization of the kinetics of phenol conversion by Pseudomonas. sp. OX1 in a continuously-operated, stirred reactor. The investigation has been carried out in a 2 L reactor, mechanically stirred. The phenol containing solution is delivered at dilution rates (D) varying from 0.025 to 0.5 h-1. The phenol conversion process has been characterized in terms of time resolved measurements the concentration in the liquid phase of phenol, cells, 2-hydroxymuconic semialdehyde, the oxygen uptake rate, the total organic carbon and the total nitrogen. Data were processed to assess the kinetic models - and related parameters – of phenol conversion and cell growth under a wide range of operating conditions, from quasi-batch up to values close to the wash-out conditions. The bacterial maintenance was also assessed for growth on phenol. Kinetic parameters and phenol-to-biomass fractional yield coefficient were significantly different from those estimated during batch cultures. The maximum phenol degradation rate was of about 0.5 g/(L h).