Use of Fungal Laccases and Peroxidases for Enzymatic Treatment of Wastewater Containing Synthetic Dyes - Green Chemistry for Dyes Removal from Wastewater - page 237

Figure 6.17 Degradation of Vat Blue 1 (indigo) by laccase from T. hir s ut a and
S. rolfsii [175].
T. hir s ut a was superior to the one from S. rolfsii in dye decolorization in
both water and from the fabrics. Redox mediators could slightly improve
the decolorization of Vat Blue 1 by T. hir s ut a and S. rolfsii laccase.
6.6.3.3 Toxicity
Abadulla et al. [54] reported a significant reduction in Pseudomonas putida
toxicity of synthetic dyes by the enzymatic treatment using T. hir s ut a lac-
case. Anthraquinone dyes Reactive Blue 19 and Acid Blue 225 could be
detoxified by 84% and 78%, respectively, by the enzymatic treatment, while
copper-chelated Reactive Blue 221 (see Figure 6.8) and diazo dye Reactive
Black 5 could be detoxified by 4% and 11%, respectively. Faraco et al. [157]
reported that enzymatic treatment of an acid dye mixture with P. ostreatus
laccase was less effective in toxicity reduction as compared with fungal
treatment with the same fungus. They used Lumistox 300 assay using
Vibrio fisheri as a toxicity assay.
6.7 ConcludingRemarks
Many research papers reviewed in this chapter clearly indicate the strong
potential of enzymatic treatment for degradation and decolorization of a
wide range of synthetic dyes using fungal enzymes such as laccases and
peroxidases. A significant amount of knowledge has been accumulated
over the years, such as sources of useful enzymes, treatability of vari-
ous synthetic dyes with different chemical structures, characteristics of
enzymes, and basic kinetics parameters of enzymatic dye decolorization
reactions, which is very encouraging. In particular, fungal laccases have
been extensively studied in the last 15 years (Table 6.3). However, fun-
gal peroxidases, including LiP, MnP, versatile peroxidase, and DyP, have
been tested to a lesser extent. The strongest advantage of this enzymatic
treatment over conventional biological processes is its rapid kinetics. The
enzymatic treatment can decolorize certain recalcitrant synthetic dyes in
less than 1 h [84,170]. A wide substrate specificity of those ligninolytic