Effects of Cyclodextrins on Dodecane Biodegradation

Bioremediation of non-chlorinated hydrocarbon-polluted soils is mainly affectedby low bioavailability, due to hydrophobicity of these xenobiotics. In fact, severalmicroorganisms can use hydrocarbons as energy and carbon sources, but theirdegradative activity takes place into the aqueous phase of the soil, where just tracesof hydrocarbons are found because of their low water solubility. So, natural attenuationusually occurs in hydrocarbon-polluted soils, but this process is very slow. It has alreadybeen demonstrated that cyclodextrins increase hydrocarbon solubility and bioavailabilityand accelerate their biodegradation. In this work it was investigated if their efficacy onbiodegradation of a model hydrocarbon (dodecane) is affected by the kind (,-, - and hydroxypropyl--cyclodextrin) and the concentrationof cyclodextrin and by environmental factors such as temperature and composition ofthe microbial indigenous population. The results obtained show that all the testedfactors influence the biodegradation kinetics. The best results were obtained with-cyclodextrin at a concentration near to its water solubility limit; moreover,biodegradation rate increases with temperature and different microbial strains showdifferent degradative activity and metabolic behaviour.