Sebastien Bonot, Rodolphe Mauchauffe, Nicolas Boscher and Henry-Michel Cauchie
Luxembourg Institute of Science and Technology, Luxembourg
Posters & Accepted Abstracts: J Drug Metab Toxicol
Due to their intensive use, antibiotics are now ubiquitous in water. They are present in sub-inhibitory concentrations and can then induce the emergence of antibiotic-resistant bacteria and bacterial ecosystem imbalances. The current water treatments are not efficient for the antibiotic elimination and can generate toxic secondary metabolites. The objective of our work is to develop enzymatic processes enhancing the antibiotics degradation with generation of non-toxic byproducts. To this end, enzymes encoded by antibiotic resistance genes (a Ã?Â²-lactamase and a New Delhi metallo-Ã?Â²-lactamase are known to degrade xenobiotics (laccase) were selected. These enzymes were covalently immobilized on biochips M Kaldnes (used in moving bed reactors) coated with either an epoxy or a quinone-rich film obtained by plasma deposition and self-polymerization of dopamine. Immobilized protein quantities varied from 12 to 95 Ã?Â¼g cm-2 and enzymatic activities were observed up to 576 hours compared to a maximum of 48 hours for the free enzymes. The degraded antibiotic concentrations were 2-15 folds higher with immobilized enzymes. The erosion tests showed that after exposure to a high water flow, the enzymes are still immobilized and active. Further, the generated metabolites show no acute toxicity (Microtox, tests on intestinal cells, Daphnia and algae ISO tests). The surface saturation with Tween 20 efficiently prevented microorganism adhesion and showed an unexpected advantage: The extension of the enzymatic activity. When the surfaces become inactive a simple protocol enables to remove the enzymes, to reload the biochips with new active enzymes and then to reach the original degradation efficiency.
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