Microbial Decolorization of Triphenylmethane Dyes - Microbial Degradation of Synthetic Dyes in Wastewaters - page 174

Fig. 2 Proposed mechanism of the Malachite green decolorization by triphenylmethane reductase
(TMR) (Kim et al. 2008 )

The involvement of cytochrome P-450 monooxygenases in Malachite green
removal was also reported in Cunninghamella elegans ATCC 36112 cultures (Cha
et al. 2001 ).

5 Mechanism and Pathways of Degradation

Many studies have been focused on involvement of possible enzymes as well as on
the structures of formed TPM intermediates. Pandey et al. ( 2011 ), based on the UV, 1 H
NMR and IR spectra, reported Crystal violet degradation by Pseudomonas uorescens

into three intermediates: 4-benzhydrylidene-cyclohexa-2,5-dienylamine hydrochlo-
ride; 4-benzhydrylidene-cyclohexa-2,5-dienol and 4-benzhydryl-cyclohexa-2,5-dien-
nol. Michler -bis[dimethylamino] benzophenone), a common TPM

dyes intermediate, was detected in degradative pathways of Methyl violet B and
Malachite green by S. decolorationis NTOU1 (Chen et al. 2010 )andBacillus cereus
DC11, respectively (Deng et al. 2008 ). Generation of leucocrystal violet and

' s ketone (N,N '

ve other

intermediates: [N,N -bis[dimethylamino] benzophenone]; [N,N-dimethylaminophe-

nyl][N-methylaminophenyl]benzophenone; N,N-dimethylaminobenzaldehyde; N,N-
dimethylaminophenol and 4-methylaminophenol during the degradation of Crystal
violet by Shewanella sp. NTOU1 was described by Chen et al. ( 2008 ). The same
intermediates of Crystal violet were produced in the liquid culture of Agrobacterium
radiobacter MTCC 8161 (Parshetti et al. 2011 ). Stepwise demethylation leading to the
yield of partially dealkylated dye molecules was the main mechanism of Victoria blue
R removal by the strain of A. calcoaceticus (Chen et al. 2011 ). The authors also
revealed that the studied bacteria could utilize the dye as a sole carbon source. The
degradative mechanism involving production of N-demethylated intermediates was
described by Chen et al. ( 2007 ), who studied Crystal violet elimination by Pseudo-
monas putida. Jadhav et al. ( 2012 ), based on the enzymatic studies and FTIR as well as
GC-MS analysis, stated asymmetric cleavage of Acid violet 19 by P. aeruginosa BCH

'