Degradation of Anthroquinone Dyes Stimulated by Fungi - Microbial Degradation of Synthetic Dyes in Wastewaters - page 330

dyes, anthraquinone dye (RBBR and B49) and azo dye R243, in a concentration
range between 200 2,000 ppm. It was also noted that both the species decolorized

anthraquinone dye RBBR and B49 more than azo dye R243 during 5 sequential
cycles. Interestingly, laccase induction was found invariably higher during decol-
orization of all dyes than the control without dyes.
Gurav et al. ( 2011 ) have also reported microbial decolorization of a very recal-
citrant insoluble Vat Red 10 dye, an anthraquinone oxazole dye, by Pseudomonas
desmolyticum NCIM2112 and Galactomyces geotrichum MTCC 1360 at pH 9 and
25

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C. It was observed that both microbes P. desmolyticum and G. geotrichum could
decolorize this dye by 55.5 and 45 %, respectively, after 23 days of incubation.
During degradation of Vat Red 10 dye, a metabolite 2,6-diisopropyl Naphthalene
(2,6-DIPN) was produced as an end product, which was found non-toxic in nature
and also served as a plant growth factor.
Murugesan et al. ( 2006 ) have observed 90 % decolorization of 50 ppm
anthraquinone dye by a laccase enzyme produced by fungus Ganoderma lucidumin
the absence of redox mediator HBT, after 20 h of incubation. It was noted that in
the presence of redox mediator HBT, the decolorization of RBBR was attained to
92 % by laccase enzyme within 2 h of incubation. Subsequently, Hadibarata et al.
( 2011 ) also investigated the degradation ability of a white rot fungus Polyporus sp.
S133 for the decolorization of 200 ppm anthraquinone dye RBBR, mediated by
laccase, induced by the presence of dye. About 26 and 60 % decolorization of this
dye were obtained after 24 and 48 h of incubation period, respectively and complete
decolorization was obtained after 72 h of incubation. It was also found that laccase
with redox mediator increased the decolorization of anthraquinone dye by 20 %.
Similarly, Forootanfar et al. ( 2012 ) also studied the decolorization of six syn-
thetic dyes using three different fungal laccases, produced by three different species
of fungi i.e. Aspergillus oryzae, Trametes versicolor and Paraconiothyrium vari-
abile. Among these fungi, laccase produced by P. variabile was found more
capable in facilitating the decolorization of all six synthetic dyes than other two
fungal strains, A. oryzae and T. versicolor, using hydroxybenzotriazole (HBT;
5 mM) as a laccase mediator. P. variabile decolorized bromophenol blue, com-
massie brilliant blue, panseu-S, rimazol brilliant blue R (RBBR), congo red and
methylene blue by 100, 91, 56, 47, 18.5 and 21.3 %, respectively, after 3 h of
incubation period. An increase in HBT concentration from 0.1 to 5 mM further
augmented the decolorization of dyes. It was also found that in the absence of HBT,
laccase from A.oryzae was able to degrade 53 % of methylene blue and 26 %
of RBBR after 30 min incubation, while 93 % of RBBR was decolorized by
T. versicolor after 3 h of incubation.
Siddiqui et al.

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( 2010 ) reported decolorization of increasing concentration

(10 200 ppm) of a reactive anthraquinone dye Dimarene Blue K2RL by a

immobilized fungus Aspergillus niger SA1. About 75 % of decolorization was
achieved in 24 h incubation with 10 ppm concentration of the dye. It was also
observed that the decolorization of dye was gradually reduced with increasing
concentration of dye i.e. 68, 40, 11, 3 and 2 % decolorization at 25, 50, 100, 200
and 300 ppm, respectively.

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