full issue - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and Pharmacy
Vol. 5 (3) 1273 -1281 July 2011, ISSN 0973-8916 (Print), 2230-7303 (Online)
1279
Decolorization to a large extent was
observed at an acidic range of pH 4.0 to pH 5.0
but maximum decolorization of RB15 and RR4
was achieved at pH 5.0 (Fig.5). It has earlier been
reported that the degradation of industrially
important dyes by peroxidases from different
sources operates to a maximum level in the
buffers of acidic pH. The incubation period is an
important parameter to study the extent of
decolorization (12, 24). Time activity plot
exhibited maximum decolorization at 90 min and
180min for RB15 and RR4 respectively (Fig.6).
The decolorization profile was unaffected or
slightly decreased over prolonged incubation
upto 5h. It was also evident from the observation
that RB15was decolorized to a greater extent
within 30 min in the presence of only 1.0 mM
HOBT, but decolorization rate was slow for RR4
under the same set of conditions. This data
supports the earlier view that decolorization rate
varies, depending upon the type of dye to be
treated (27).
The rate of decolorization of dye mixture
was also studied which was slower in comparison
to that of individual dyes both in the presence
and absence of HOBT (data not shown).
However, the HOBT mediated dye
decolorization was more effective. This finding
is consistent with the earlier observation that the
biodegradation of various phenols in the form
of mixtures was quite slow compared to the
independent phenol (28). Several workers have
demonstrated that the use of redox mediator
system enhanced the rate of dye decolorization
by several folds but these mediators were
required in very high concentrations (29, 30).
The salt fractionated peroxidase from T.
dioica significantly catalyzed the decolorization/
degradation of reactive textile dyes.
Decolorization enhanced remarkably in the
presence of redox mediator HOBT which was
effective at low concentration. Traditional
wastewater treatment technologies have proven
to be markedly ineffective for handling
wastewater of synthetic textile dyes due to the
chemical stability of these pollutants. Therefore,
establishment of result oriented enzyme based
cheap and ecofriendly techniques holds
considerable promise. Thus, this study
demonstrated that T. dioica peroxidase in its salt
fractionated state can be coupled with low
concentration of redox mediators to cause
effective decolorization of synthetic and
recalcitrant reactive dyes.
Acknowledgement
I am thankful to Mr. Tabish Qidwai and
Mr. Prabhask K Pandey for their experimental
contributions and to the Department of Science
and Technology under the Ministry of Science
and Technology for providing infrastructure
support to the department of Biochemistry for
carrying out this work.
References
1. Pierce, J. (1994). Colour in textile
effluents—the origins of the problem. J.
Soc. Dyers Colour, 110: 131–134.
2. Kilic, NK, Nielson, JP, Yuce, M. and
Donmez, G. (2007). Characterization of a
simple bacterial consortium for effective
treatment of wastewaters with reactive dyes
and CrVI. Chemosphere, 67: 826–831.
3. Sumathi, S. and Manju, B.S. (2000).
Uptake of reactive textile dyes by
Aspergillus foetidus. Enzyme Microbial
Technology, 27: 347–355.
4. Keharia, H. and Madamvar, D. (2003).
Bioremediation concept for treatment of
dye containing wastewater: a review. I J
Exp Biology, 41:1068–1075.
Simple approach to reactive dye decolorization