title: Decolorization and biotransformation of triphenylmethane dye, methyl violet, by Aspergillus sp. isolated from Ladakh, India.
abstract: 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 25 degrees C. 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 30 degrees C 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.
authors.affiliation: Chemical Biology Laboratory, Indian Institute of Chemical Technology, Hyderabad, India. cgkumar@iict.res.in
authors.forename: C Ganesh
authors.initials: CG
authors.lastname: Kumar
authors.forename: Poornima
authors.initials: P
authors.lastname: Mongolla
authors.forename: Anver
authors.initials: A
authors.lastname: Basha
authors.forename: Joveeta
authors.initials: J
authors.lastname: Joseph
authors.forename: V U M
authors.initials: VU
authors.lastname: Sarma
authors.forename: Ahmed
authors.initials: A
authors.lastname: Kamal
mesh_terms: D000332:Aerobiosis; D001230:Aspergillus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001711:Biotransformation; D002244:Carbon / Q000378:metabolism; D002853:Chromatography, Liquid; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism*; D005840:Gentian Violet / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007194:India; D007700:Kinetics; D013058:Mass Spectrometry; D009584:Nitrogen / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014320:Triphenylmethyl Compounds / Q000378:metabolism; D014871:Water Microbiology
chemical_list: D004396:Coloring Agents; D014320:Triphenylmethyl Compounds; D002244:Carbon; C046945:triphenylmethane; D005840:Gentian Violet; D009584:Nitrogen