Enzymatic degradation of chloramphenicol by laccase from Trametes hirsuta and comparison among mediators

The laccase enzyme from white-rot fungus Trametes hirsuta brought about degradation of 0.5 mg/L chloramphenicol within seven days without mediators, which is typically found in the pharmaceutical wastes. This study is first of its kind which showed that the higher concentrations of chloramphenicol (10 mg/L) was efficiently degraded in the presence of laccase mediator system (LMS) like syringaldehyde, vanillin, ABTS and a naphthol. The addition of mediators escalated the degradation process from 10% to 100% within 48 h. The kinetic parameter V-max of the laccase mediated degradation reactions with and without mediators comprehensively proved the potentiality of laccase and its redox mediators in bioremediation of most stable micro pollutants i.e., antibiotics in the pharmaceutical wastes. Further, the laccase mediated degradation of chloramphenicol was confirmed by the microbial susceptibility assay. The formation of chloramphenicol aldehyde after degradation of chloramphenicol was confirmed through LC-MS analysis and proved to be non-toxic to the tested micro-organisms.