Biodegradation of three tetracyclines in river sediment

Tetracyclines (TCs), including tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) are widely used in human and veterinary medicine. We investigated the aerobic degradation of three TCs in river sediment from southern Taiwan. The degradation rates in the sediment were in the order of CTC > OTC > TC. Sediment samples were separated into fractions with particle size from 2-50 to 500-2000 μm. Sediment fractions with smaller particle sizes demonstrated higher degradation rates. The sediment particle size affected the amount of the microbial community present, as did the various treatments in sediment. Degradation of TCs in sediment was enhanced by the addition of enzyme extract from spent mushroom compost of Pleurotus eryngii and was higher with extract-containing microcapsules than suspended enzyme extract. The addition of extract-containing microcapsules enhanced the removal rates of the three TCs, and 2 additions of TCs maintained the extract-containing microcapsule activity in sediment in bioreactor. The system to immobilize TCs we developed is stable and could be used in bioremediation applications.