Production and immobilization of laccases from monoculture and co-culture of Trametes villosa and Pycnoporus sanguineus for sustainable biodegradation of ciprofloxacin

The presence of antibiotics in water systems and drinking water has detrimental effects on various organisms and poses health risks to both animals and humans. This study describes a sustainable approach using laccases to remove ciprofloxacin from water solutions. Laccases produced by monoculture of Trametes villosa and in co-culture with Pycnoporus sanguineus were immobilized using the method of cross-linked enzyme aggregates (CLEAs). The immobilization process was statistically optimized, and the biocatalysts were characterized and applied for biodegradation of ciprofloxacin at different concentrations. Laccase production was enhanced in co-culture conditions, yielding isoforms of molecular masses ranging from 55 to 45kDa. Optimum conditions for immobilizing laccases by CLEAs were achieved with ammonium sulfate as a precipitant and glutaraldehyde as a cross-linker. Immobilization improved the thermal stability of the enzymes at 40 °C and 55 °C, and both forms of laccase CLEAs retained approximately 38% of their initial activity after five reuse cycles. Free and immobilized laccases demonstrated comparable efficiency in removing ciprofloxacin from aqueous solutions (at 2.5mgL-1) with a 53-62% removal rate in the presence of 4-hydroxybenzoic acid as a natural redox mediator. The degradation of ciprofloxacin by laccases also reduced its antimicrobial activity against Escherichia coli.