Application of a Doehlert experimental design to the optimization of microbial degradation of crude oil in sea water by continuous culture

Abstract

Crude oil was degraded by a mixed bacterial community grown in continuous culture on sea water. The fermentation process included an emulsification step prior to the introduction of the substrate in the reactor, with external cell recycling by a tangential-flow filtration system. Optimization of the fermentation technique was achieved by using the surface response methodology (Doehlert experimental design). Besides reducing the number of experiments, this approach allowed optimal experimental conditions to be chosen, for the particular goal: percent degradation of crude oil (80%), biomass (7.6 g·l-1) and degradation rate (0.73 g·l-1·h-1). This biodegradation process could be used as a tool to fight against pollutions by petroleum products.