A study of a bacterial immobilization substratum for use in the bioremediation of crude oil in a saltwater system

An immobilization matrix, Drizit, was examined for use in the bioremediation of oil in a saltwater system. The support was examined by scanning electron microscopy, cell-loading capacity, absorption of Ekofisk crude oil, the effect on cell recoverability of drying Drizit-immobilized cells at room temperature, 55 degrees C or freeze drying and storage for up to 3 months, and the capability of immobilized Pseudomonas fluorescens to enhance biodegradation of petrol (Slovene diesel) in a saltwater system. Results showed that Drizit is an ideal immobilization substratum for use in bioremediation, and the substratum was found to have a good cell-loading capacity (3.75 mg protein g(-1) substratum) and a high absorbency of oil (7.49 g Ekofisk g(-1) substratum). After drying the immobilized cells at room temperature, 55 degrees C or freeze drying and subsequent storage, cells were not recoverable after 2 weeks, 1 week or 2 months, respectively, and a significant decrease was seen in the number of cells recovered after drying and 1 week's storage in all cases. Enhanced biodegradation of C-13-C-18 pristane and phytane, in petrol (Slovene diesel) occurred with the immobilization of Ps. fluorescens to Drizit. An average degradation of 73.8% occurred in the immobilized system in comparison with the free system which resulted in an average degradation of 39.8%. When the two systems were supplemented with nitrates and phosphates, degradation in the free supplemented system increased to an average of 72.4%. However, no significant difference in biodegradation was found between the immobilized system and the immobilized system supplemented with nitrates and phosphates which achieved an average degradation of 74.15%.