Biodegradation of Diesel by Free and Immobilized <i>Chromobacterium violaceum</i>

Pollution from oil and its derivatives has significantly affected terrestrial and marine ecosystems around the world. The use of microorganisms with the ability to biodegrade these contaminants has been proven as an alternative to remediate contaminated sites. This research estimated the biodegradation efficiency of Total Petroleum Hydrocarbons (TPHs) and phenols present in a commercial sample of diesel by <i>Chromobacterium violaceum</i> ATCC 12472 at a laboratory scale. We quantified the decrease in the concentration of phenols and TPHs by <i>C. violaceum</i> by free and immobilized cells in calcium alginate beads, as well as by <i>Pseudomonas aeruginosa</i> ATCC 9027 (positive control). The biodegradation of TPHs by <i>C. violaceum</i> during 10 days of treatment was 10% in free cells and 19% in immobilized cells, while for <i>P. aeruginosa</i>, it was 16 and 25%, respectively. In relation to phenols, biodegradation by free cells of <i>C. violaceum</i> was 83% and 86% by immobilized cells, while <i>P. aeruginosa</i> was 83 and 85%, respectively. These results indicate that cell immobilization enhanced the biodegradation of TPHs but not of phenols. Therefore, <i>C. violaceum</i> is a good alternative for the treatment of process water with hydrocarbons almost as efficient as <i>P. aeruginosa</i>. Additionally, the immobilization of cells in calcium alginate beads represents an alternative to obtain greater efficiencies in the removal of TPHs.