Elucidation of fungal dye-decolourizing peroxidase (DyP) and ligninolytic enzyme activities in decolourization and mineralization of azo dyes.

Abstract

The aim of the study is to investigate the efficiency of Geotrichum candidum in the decolourization and mineralization of synthetic azo dyes. It includes screening of enzymes from G. candidum and its optimization, followed by decolourization and mineralization studies. Decolourization was observed to be maximum in methyl orange (94·6%) followed by Congo red (85%), trypan blue (70·4%) and Eriochrome Black T (55·6%) in 48h, suggesting the plausible degradation of the azo dyes by G. candidum. The enzyme activity study showed that DyP-type peroxidase has highest activity of 900mUml-1 compared to that of laccase (405mUml-1 ) and lignin peroxidase (LiP) (324mUml-1 ) at optimized pH (6) and temperature (35°C). Moreover, the rate of decolourization was found to be directly proportional to the production of laccase and LiP, unlike DyP-type peroxidase. Furthermore, mineralization study demonstrated reduction in aromatic amines, showing 20% mineralization of methyl orange. Geotrichum candidum with its enzyme system is able to efficiently decolourize and mineralize the experimental azo dyes. The efficient decolourization and mineralization of azo dyes makes G. candidum a promising alternative in the treatment of textile effluent contaminated with azo dyes.