Semi-continuous biodegradation of carbazole in fuels by biofilm-immobilised cells of Burkholderia sp. strain IMP5GC

Carbazole, a nitrogen-containing aromatic compound naturally present in fossil fuels, is responsible for the poisoning of catalysts used in the hydrodesulfurisation process to obtain clean low-sulfur fuels. Burkholderia sp. strain IMP5GC displays very good carbazole-degrading activity and resistance to petroleum distillates for short times. Herein we report the biofilm-immobilisation of Burkholderia sp. IMP5GC and its use in a packed reactor for the semi-continuous degradation of carbazole present in a mixture of gas oil and light cycle oil. The ratio of water to organic phase was only 0.1. The specific activity of carbazole degradation for the immobilised cells was half of that for the free cells. In contrast, the carbazole-degrading activity of the biofilm-immobilised cells was stable. The reactor was successfully operated in semi-continuous form employing a mixture of gas oil and light cycle oil as influent.