Synthesis and characterization of electrospun nanofibers for the immobilization of a cocktail of native laccases from Pycnoporus sanguineus CS:43 and their evaluation in the biotransformation of 2,4,6-trinitrotoluene

Abstract

Enzymatic biotransformation stands as an eco-friendly strategy for eliminating toxic contaminants like 2,4,6-trinitrotoluene (TNT). Moreover, the application of immobilized biocatalysis is relevant for industrial applications due to the improved stability and reusability of the immobilized enzymes. In the present study, an enzymatic cocktail containing laccases from a native fungus from the northeastern of Mexico (Pycnoporus Ssanguineus CS43) was immobilized in nanofibers. The study explores three biopolymer mixtures—polyalcohol vinyl (PVA), PVA/alginate (PVA/SA), and PVA/chitosan (PVA/CS)—for nanofiber preparation and employs three distinct immobilization strategies: entrapment, adsorption, and covalent bonding. Among them entrapped laccases in PVA/SA nanofibers showed the highest immobilization rate (96.92%) and retained 77.85% activity after five cycles using 2,2-azino- bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) as substrate. Preliminary kinetic parameters and optimal pH/temperature were determined, comparing the cocktail of immobilized laccases to free ones. The application of this system resulted in a substantial 93.43% TNT removal at pH 7 and 25 °C within four days, preserving 24.13% activity after five cycles. Significantly, this study marks the pioneering use of immobilized laccase for TNT biotransformation, offering a promising eco-friendly strategy for tackling persistent pollutants such as TNT.