Effect of Dye Structure on the Decolorisation Efficiency of Candida Tropicalis and Bacillus Firmus

Heterocyclic monoazo disperse dyes constitute an important class of textile colorants and are used in the coloration of hydrophobic substrates, with a large share of all the disperse dyes being used for coloration of polyester and its blends. In view of the dearth of effective methods, the need to develop protocols for decolorisation/ degradation of these dyes is fuelled. Decolorisation/degradation of heterocyclic monoazo disperse dyes were tested using Candida tropicalis and Bacillus firmus respectively isolated from dye contaminated soil samples and sludge of domestic seweage drain and the correlation of decolorisation with dye molecular structure has been drawn with the microbial decolorisation efficiency. The results reveal that there is a significant difference between the decolorizing ability of Candida tropicalis and Bacillus firmus respectively, under their respective conditions. Degradation of dyes by both these cultures was driven by a qualitatively visualized hydrophilic-hydrophobic balance of the chromophores as well as the extent to which a dye was adsorbed on cell mass.