Degradation of Anthroquinone Dyes Stimulated by Fungi - Microbial Degradation of Synthetic Dyes in Wastewaters - page 328

as compared to physical and chemical processes and its degradation may lead to
complete mineralization at a very low cost (Pandey et al. 2007 ). Several potential
microorganisms have been identi

ed among fungi, bacteria, yeasts and algae, for
their high ability to decolorize many anthraquinone dyes (Pandey et al. 2007 ).
In the bioremediation methods, microbial decolorization/degradation as well as
dye adsorption by living or dead microbial biomass are commonly recommended
for the treatment of industrial dye ef uents (Fu and Viraraghavan 2001 ; McMullan

et al. 2001 ).
In biological treatments, white rot fungi (WRF) have sustained our increasing
interest, because several studies have reported their high ability for the decoloriza-
tion and toxicity reduction of dyes (Fu and Viraraghavan 2001 ). White rot fungi
secrete severalextracellular enzymes which facilitate the remarkable biotransfor-
mation or biodegradation of a broad variety of synthetic dyes (Wesenberg et al.
2003 ). In the enzyme-based methods, the energy requirement is very low and also
poses a minimal adverse impact on the ecosystems. Among extracellular enzymes,
laccases have aroused immense interest, because of their remarkable ability to
transform a wide variety of hazardous chemicals (Majeau et al. 2010 ). They also act
as useful biocatalysts for wider biotechnological applications, due to their non-
speci c oxidation capacity and ability to use available molecular oxygen as an

electron acceptor (Baldrian 2006 ). Dead fungal biomass is also considered as a
suitable alternative for bioremediation, as its wastes don ' t have toxic effect. In
addition, it does not require any nutrients, nor does it release toxins or propagules in
the environment (Tigini et al. 2011 ).

2 Degradation of Anthraquinone Dyes by Fungi

Knapp et al. ( 1995 ) have reported that wood rotting basidiomycetes fungi (WRF)
are highly capable of degrading synthetic dyes. While working on the biodegra-
dation of 14 structurally different synthetic dyes by wood-rotting basidiomycetes
fungi, it was found that the decomposition rate highly depends on both the chemical
structure of the dye and the characteristics of the fungi. Therefore, white-rot fungi
have been widely used for the decoloration of different dyes. Trametes versicolor
has ability to decolorize anthraquinone, azo and indigo-based dyes (Wang and Yu
1998 ). A rapid decoloration of Remazol Brilliant Blue (RBBR) by Pycnoporus
cinnabarinus in packed-bed bioreactor was reported by Schliephaje and Lonergan
( 1996 ). Abadulla et al. ( 2000 ) also observed decoloration of different synthetic
dyes, such as anthraquinone, triarylmethane, indigoid, by a fungus Trametes hir-
sute. Verma et al. ( 2012 ) reported a rapid two- step process for the bioremediation
of 1,000 ppm anthraquinone Reactive Blue 4 (RB4) dye by laccase enzyme pro-
duced by marine-borne basidiomycetous fungus Cerrena unicolor, which caused
61 % of color removal and two-fold decrease in COD after 12 h of incubation. A
change in aromatic structure of dye with concomitant formation of many low
molecular weight phenolic compounds was also observed during degradation of