Dye Decolourisation Using Two Klebsiella Strains

This study aimed to decolourise different dyes using two Klebsiella strains (Bz4 and Rz7) in different concentrations and incubation conditions. Azo (Evans blue (EB)) and triphenylmethane (brilliant green (BG)) dyes were used individually and in mixture. The toxicity of the biotransformation products was estimated. Both strains had a significant potential to decolourise the dyes in the fluorone, azo and triphenylmethane classes. The type and concentration of dye affects the decolourisation effectiveness. Differences in the dye removal potential were observed particularly in the main experiment. The best results were obtained for Bz4 in the samples with EB (up to 95.4 %) and dye mixture (up to 99 %) and for Rz7 with BG (100 %). The living and dead biomass of the strain Bz4 highly absorbs the dyes. Significant effect of the process conditions was noticed for both strains. The best results were obtained in static and semistatic samples (89–99 %) for the removal of EB and a mixture of dyes and in static samples (100 %) for BG. The decrease in zootoxicity (from class IV/V) was noticed in all samples with living biomass of the strain Bz4 (to class III/IV) and in samples with single dyes for Rz7 (to class III/IV). The decrease in phytotoxicity (from class III/IV) was noticed for Bz4 in the samples with BG and a mixture (to class III) and for Rz7 in the samples with BG (to class III). The process conditions did not affect the changes in toxicity after the process.