Microbial Decolorization of Triphenylmethane Dyes

Abstract

Two aerobic bacterial isolates C1A and C2B from dye contaminated soils showed maximum decolorization of crystal violet (20 ppm) and malachite green (100 ppm). In minimal media 68 % decolorization of crystal violet and 89 % decolorization of malachite green was observed by C1A. Malachite green was the compound most remarkably decolorized than crystal violet. Dye decolorization occurred by the dead cells indicating that decolorization is largely due to adsorption to the extent of nearly 60 %. Growth of bacteria in minimal media and increase in viable cell count showed that dye could be utilized by the bacterial systems under conditions of starvation accounting for 30 - 40 % decolorization. Dye decolorization by the immobilized bacterial systems was more than 80 %. Among different solid wastes used as adsorbents the decolorization of dye was in the order of activated charcoal >fly ash > mycelial waste. C1A may be a promising bacterium to depollute the effluent containing triphenylmethane dyes which also could decolorize synthetic effluent containing a mixture of crystal violet and malachite green.