Biotransformation of the Fluoroquinolone Antibiotic, Levofloxacin, by the Free and Immobilized Secretome of Coriolopsis gallica

Antibiotics play a crucial role in human and animal medical healthcare, but widespread use and overuse of antibiotics poses alarming health and environmental issues. Fluoroquinolones constitute a class of antibiotics that has already become ubiquitous in the environment, and their increasing use and high persistence prompt growing concern. Here we investigated a fungal secretome prepared from the white-rot fungus <i>Coriolopsis gallica</i>, which is able to effectively degrade the environmentally persistent fluoroquinolone, levofloxacin. We tested various physical-chemical factors such as concentrations of 1-hydroxybenzotriazol (HBT), of enzyme, and of antibiotic, and pH and temperature of the reaction for biotransformation of the antibiotic. We compared the free with the immobilized <i>Coriolopsis gallica</i> secretome proteins, and analyzed the collective reaction products for residual activity against <i>E. coli</i> (growth inhibition test). We also performed HPLC analysis. The results show that treatment with the free secretome yielded a highest removal efficiency of 50 mg L^-1 levofloxacin in the presence of 2.5 mM HBT, whereas the immobilized secretome was only able to degrade 10 mg L^-1 levofloxacin with the same concentration of mediator, but presenting the advantage of being reusable.