Degradation of Anthroquinone Dyes Stimulated by Fungi - Microbial Degradation of Synthetic Dyes in Wastewaters - page 331

Andleeb et al. ( 2012 ) investigated the degradation and decolorization of
anthraquinone dye Dimarene Blue K2RL by a fungus Aspergillus avus SA2 in a
lab scale immobilized

uidized bed bioreactor (FBR) system. It was observed that
the fungus decolorized dye having higher concentration (up to 500 ppm), to a
greater extent with a lower retention time (72 h) than that previously reported by
Sharma et al. ( 2004a , b , c ). About 71.3 % of the (50 ppm) Dimarene Blue K2RL
dye was removed by A. avus in the bioreactor system (FBR) after 24 h of incu-

bation period. Different metabolites, formed during decolorization and degradation
of this dye were identi

ed as phthalic acid, benzoic acid, 1,4-dihydroxyanthra-
quinone, 2,3-dihydro-9,10-dihydroxy-1,4-anthracenedione, and catechol.
Ngieng et al. ( 2013 ) have also examined the decolorization of various synthetic
dyes i.e., Congo red, Orange G, and Methyl red and Remazol brilliant blue R
(RBBR) by twentyendophytic fungi isolated from Melastoma malabathricum
(Senduduk). It was observed that out of twenty, only one strain MS8 was able to
decolorize all the four dyes with 200 ppm concentration. This fungus completely
decolorized the RBBR and Orange G dye in the agar medium within 8 days. When
the decolorization was analyzed quantitatively in aqueous minimal medium, the
percent decolorization for RBBR, Orange G, Congo red and Methyl red was found
to be 97, 33, 48 and 56 %, respectively, within 16 days of incubation.
More recently, Korniollowicz-Kowalska and Rybczynska ( 2014 ) reported
decolorization of two anthraquinone dyes, Ac and Poly R-478 by anamorphic
fungusBjerkandera adusta CCBAS 930. It was found that about 72 % of the color,
which was generally caused by 0.01 % Ac, was removed by B. adusta CCBAS 930
after 4 days of incubation. This corresponded to 76.82 % reduction of the con-
centration of dye. Similarly, 70 % decolorization of 0.01 % Poly R-478 was
observed, corresponding to a reduction of 77.28 % in the dye concentration by this
fungus after 14 days of incubation.

3 Degradative Enzymes for Synthetic Dyes

The fungi are able to metabolize a wide range of carbon and nitrogen sources for
their survival, mediated byextracellular enzymes, such as lignin peroxidase, man-
ganese peroxidase and laccase (Saratale et al. 2007 ). Since these enzymes degrade
many complex organic pollutants, they are found to be the most appropriate in the
treatment of colored and metallic ef

uents (Ezeronye and Okerentugba 1999 ).

3.1 Lignin Peroxidase (LiP): (EC: 1.11.1.14)

Lignin peroxidase (LiP) enzyme is a heme containing protein and was rst time

detected in cultures of Phanerochaete chrysosporium. It is a monomeric N- and
O-glycosylated protein and found in several

iso-forms. (Tien and Kirk 1983 ;