Production of a Rhodococcus erythropolis IGTS8 biocatalyst for DBT biodesulfurization:: influence of operational conditions

The influence of operational conditions, such as temperature (from 26 to 36degreesC), pH (with and without control) and dissolved oxygen concentration (with and without control), has been studied during growth in batch of Rhododoccus erythropolis IGTS8. This bacteria has the ability to convert dibenzothiophene (DBT) into 2-hydroxybyphenyl (HBP), desulfurizing the organic molecule. In order to get the best conditions to obtain desulfurizing cells, a parameter (DBDS) including both biomass concentration and time to reach a particular percentage of desulfurizing capability (X-BDS) has been employed. The optimum value of D-BDS has been obtained under the following working conditions: 30degreesC of temperature, pH 6.5 and a dissolved oxygen concentration constant value of 10% saturation. A kinetic model based on a logistic equation was applied to describe biomass concentration during R. erythropolis IGTS8 growth. Kinetic model parameters (mu and C-X(max) ) were obtained under several operational conditions. A model was applied to describe biodesulfurization capability evolution during growth. Predicted values of biomass concentration and biodesulfurizing capability percentage achieved by the cells can be obtained during R. erythropolis IGTS8 growth, with very close values to those found experimentally. (C) 2004 Elsevier B.V. All rights reserved.