Immobilized-enzyme reactors designed to treat antibiotics from wastewater: first results of the feasibility study.

Antibiotics are extensively used for human and animal treatment and their global consumption is estimated will increase. Due to their low biodegradability, they cause serious environmental pollution. The phenomenon of antibiotic resistance is the main risk to human health because the microbial community, thanks to evolution processes, can survive common antibiotics, making their action ineffective. Thus, the goal of this study is to identify fungal laccases that are active on antibiotics and to perform a feasibility study for the development of immobilized-enzyme bioreactors. Firstly, it was measured the reduction of bactericidal activity of six after treatment with four different laccases derived from five different sources, showing the inactivation of amoxicillin and tetracycline by commercial laccase from Aspergiullus sp. was achieved. Then, the optimal operational conditions for the commercial laccase were found (pH 8 and at temperature of 37C) to perform the degradation treatment. The results show that amoxicillin concentration is reduced by 40% when the starting solution had a concentration of 4 mg/L and the efficiency of the treatment decreased if the amount of substrate increased. Given that free enzymes have low stability and that they would lose after the treatment, it is necessary to immobilize them. Thus, the laccase was immobilized into Ca-alginate beads concluding that it is an efficient immobilization technic because the amount of total enzyme entrapped in the beads corresponds to 99.5% of the amount inserted to be immobilized.