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KMID : 0545120110210030267
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Journal of Microbiology and Biotechnology
2011 Volume.21 No. 3 p.267 ~ p.273
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Decolorization and Biotransformation of Triphenylmethane Dye, Methyl Violet, by Aspergillus sp. Isolated from Ladakh, India
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C. Ganesh Kumar
Poornima Mongolla
Anver Basha
Joveeta Joseph
V.U.M. Sarma
Ahmed Kamal
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Abstract
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Methyl violet, used extensively in the commercial textile industry and as a biological stain, is a hazardous recalcitrant. Aspergillus sp. strain CB-TKL-1 isolated from a water sample from Tsumoriri Lake, Karzok, Ladakh, India, was found to completely decolorize methyl violet within 24 h when cultured under aerobic conditions at 25oC. The rate of decolorization was determined by monitoring the decrease in the absorbance maxima of the dye by UV-visible spectroscopy. The decolorization of methyl violet was optimal at pH 5.5 and 30oC when agitated at 200 rpm. Addition of glucose or arabinose (2%) as a carbon source and sodium nitrate or soyapeptone (0.2%) as a nitrogen source enhanced the decolorization ability of the culture. Furthermore, the culture exhibited a maximum decolorization rate of methyl violet after 24 h when the C:N ratio was 10. Nine N-demethylated decolorized products of methyl violet were identified based on UV-visible spectroscopy, Fourier transform infrared (FTIR), and LC-MS analyses. The decolorization of methyl violet at the end of 24 h generated mono-, di-, tri-, tetra-, penta-, and hexa-Ndemethylated intermediates of pararosaniline. The variation of the relative absorption peaks in the decolorized sample indicated a linear decrease of hexa-N-demethylated compounds to non-N-demethylated pararosaniline, indicating a stepwise N-demethylation in the decolorization process.
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KEYWORD
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Aspergillus, decolorization, dyes, methyl violet, N-demethylation, biotransformation
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