Environmental Engineering Reference
In-Depth Information
Acid green 27, Acid violet 7 and Indigo carmine dyes on living and dead mycelia of
Trametes versicolour. Yong and Yu (
1997
) suggested the binding of dyes to the
fungal hyphae, physical adsorption and enzymatic degradation by extracellular and
intracellular enzymes as major mechanisms for the color removal. Besides,
enzymes, such as lignin peroxidase (LiP), manganese-dependent peroxidase (MnP)
and laccase, which are involved in lignin degradation, have been reported to
decolorize dyes (Vyas and Molitoris
1995
). Dyes with different structures are
decolorized at different intrinsic enzymatic rates. Kim et al. (
1996
) demonstrated
that presence of H
2
O
2
-dependent enzyme activity declourized Remozol Brilliant
Blue R in the culture
ltrate of Pleurotus ostreatus in a chemically de
ned medium.
ed and characterized a novel peroxidase (Dyp)
which is responsible for the dye-decolorizing activity of Geotrichum candidum Dec
1. Nine of the 21 types of dyes were decolorized by Dec 1, and in particular,
anthroquinone dyes were effectively decolorized. Swamy and Ramsay (
1999
)
reported that in fungus, Trametes versicolour, lignin peroxidase (Lip) was not
detected during decolorization of the azo dye of Amaranth, while laccase and
manganese peroxidase (MnP) were detected in the decolorizing cultures. A white-
rot fungus, Thelephora sp. was isolated from the Western Ghats of South India and
characterized for its lignolytic enzymes (Selvam
2000
). Roushdy and Abdel-
Shakour (
2011
) found that lignin peroxidase produced by Cunninghamella elegans
was capable for 100 % decolorization of Malachite green dye under static condition,
whereas no decolorization was observed in shaking condition. They also showed
that Malachite green was degraded and decolorized under ligninolytic conditions.
This indicated that ligninolytic enzymes were essential for the degradation of this
dye by the fungal strain Cunninghamella elegans. Won et al. (
2000
) also stated that
lignin degradation system of the fungi had been directly as well as indirectly linked
to the degradation of various compound remains. Other studies reported that
Malachite green was enzymatically reduced to leucomalachite green and also
converted to N-demethylated and N-oxidized metabolites (Cha et al.
2001
).
Traditionally, fungi have been classi
Kim and Shoda (
1999
) have puri
ed as white-, brown-, or soft-rot fungi on the
basis of technical decay descriptions (Nilsson
1988
), regardless of their taxonomic
position. Because the enzyme systems and metabolic pathways involved in the
breakdown of carbohydrates and lignins are truly distinct in these fungi, rather than
just modi
cant
taxonomic importance. One important physiological characteristic of decay fungi in
culture is production of extracellular phenoloxidases and peroxidases. Certain fungi
produce brown diffusion zones in agar plates supplemented with 0.5 % (w/v) gallic or
tannic acid, as a result of oxidation of the respective phenolic acid by extra- or intra-
cellular phenoloxidases. Bavendamm (
1928
) suggested that the presence of phe-
noloxidases was correlated with fungi causing white-rot decay and that only these
fungi were able to completely decompose lignin. Davidson et al. (
1938
) extended this
method
ed in one or a few speci
c enzyme activities, decay type is of signi
rst time to 210 species of wood decaying fungi. Of all tested white-rot fungi,
96 % were positive on gallic acid agar, tannic acid agar, or both. Kaarik (
1965
) tested
173 wood-decaying species on the plates supplemented with 28 substances and found
wide variations in the reactions of these strains to speci
c phenolic compounds.
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