Kinetic analyses of desulfurization of dibenzothiophene by Rhodococcus erythropolis in continuous cultures

Abstract

Rhodococcus erythropolis N1-36, a desulfurization strain, was grown in continuous culture at 10 different dilution rates with 50 μM dibenzothiophene sulfone (DBTO2) as the growth-limiting nutrient. The steady-state biomass, concentrations of substrate (DBTO2) and product (monohydroxybiphenyl), saturation constant (0.39 μM DBTO2), and cell yield coefficient (9 mg of biomass · μM-1 DBTO2) were measured. Continuous cultures at five temperatures allowed calculation of activation energy (0.84 kcal · mol-1 [ca. 3.5 kJ · mol-1]) near the optimal temperature (30°C) for growth. A washout technique was used to calculate the maximum specific growth rate (0.235 h-1), a value equivalent to a minimum generation time of 2.95 h.