The enzymatic decolorization of leather azo dyes (AB 113 and AB 52) using crude fungal laccase: an eco-friendly approach towards pollution reduction

In the current investigation, crude laccase was utilized to decolorize the leather azo dyes (AB 113 and AB 52). The crude laccase was extracted from Penicillium chrysogenum strain TSV1 pH 5.5, temp. at 32 degrees C for 7 days in a liquid culture medium, and shows maximum enzyme activity of 7.92 U/mL. The crude laccase has been applied and achieved maximum decolorization efficiency up to 83% and 69% respectively for AB 113 and AB 52 within 48-h duration. Furthermore, the addition of 1 mM HOBT mediator has enhanced the dye decolorization rate up to 98% and 85% within 24-h duration respectively for both dyes. Furthermore, the decolorization was confirmed by UV-Vis spectra analysis and has showed peaks at 570 nm and 580 nm which corresponded to chromophores respectively for both dyes and disappeared after decolorization. The bands were observed at the bending region from 1561 to 1494 cm-1 and from 1344 to 1031 cm-1 by FTIR analysis corresponding to an aromatic ring of AB 113. Similarly, the peaks observed at 1589cm-1 and 1451cm-1 corresponded to the aromatic region of AB 52 and indicated the presence of -N=N-. These bands disappeared and new bands appeared after decolorization. The UPLC analysis has shown different peaks at various retention times for both dyes and these peaks disappeared after decolorization. Furthermore, the COD (86.5 +/- 5% and 83.52 +/- 3%) and TOC (87.86% and 83.82%) have been reduced for both dyes. The toxicity of the dyes also has been reduced after decolorization. The laccase was a more potential enzyme for the decolorization of azo dyes.