Decolorization of textile dyes by whole cultures of Ischnoderma resinosum and by purified laccase and Mn-peroxidase

Abstract

Ischnoderma resinosum produced extracellular ligninolytic enzymes laccase and MnP. The activity of laccase achieved the maximum on day 10 (29.4 U L −1), the MnP on day 14 (34.5 U L −1). Laccase and Mn-peroxidase were purified from the culture liquid using gel permeation and ion-exchange chromatographies. Purified Mn-peroxidase performed decolorization of all textile dyes tested (Reactive Black 5, Reactive Blue 19, Reactive Red 22 and Reactive Yellow 15). Laccase was inactive with Reactive Black 5 and Reactive Red 22, while all dyes were decolorized after addition of the redox mediators violuric acid (VA) and hydroxybenzotriazole (HBT). The culture liquid from I. resinosum cultures was also able to decolorize all dyes as well as the synthetic dyebaths in the presence of VA and HBT. The highest decolorization rates were detected in acidic pH (3–4).