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