BIODEGRADATION AND DEGRADATION PRODUCTS OF TETRACYCLINE BY COCHLIOBOLUS LUNATUS.

Tetracycline antibiotics (TCs) are widely used in human and veterinary medicine. The release of TCs into the environment is of considerable concern because persistent antibiotic residue may lead to the development of antibiotic-resistant bacteria, so a bio-friendly treatment method is required. In this study, a fungus Cochliobolus lunatus (no. Cyc15) was chosen on the basis of remarkable reduction (89%) of tetracycline (TC). Four main degradation products were separated by HPLC and determined to be N-[(2E)-3-(3-methyl-2-oxo-2H-pyran-6-yl)-1- oxo-2-buten-1-yl] glycine, 3-hydroxy-4-hexenoic acid, 5-methoxy-2-methylchromone and 3,4- dihydro-8-hydroxy-3-methyl-1H-2-benzopyran-1- one, which had lower molecular weights and lower toxicities. We also investigated the use of a microcapsule column chromatography system that immobilized the fungal cells in chitosan-Ca-alginate microcapsules by an emulsification/internal gelation technique for a laboratory-scale reproducibility experiment. Compared with the results by free fungal cells, immobilization protected the fungal cells well, the biodegradability of the fungus was stable, and the degradation products were nearly unchanged. This suggests that the immobilized fungal cells of C. lunatus (no. Cyc15) we developed were stable and efficient and could be used in bioremediation applications. [ABSTRACT FROM AUTHOR]