Polysaccharide conjugated laccase for the dye decolorization and reusability of effluent in textile industry

- Pronounced thermal and pH instability was shown by gum Arabic conjugated laccase.
- Thermal instability of conjugate was confirmed by differential scanning colorimeter.
- Structural changes in laccase was analysed by fluorescence spectrophotometer.
- Textile effluent containing Remazol brilliant blue R was decolorized enzymatically.
- Effluent treated with conjugated laccase can be reused as liquor for dyeing process.

Nine different polysaccharides were screened for conjugation with laccase and evaluated for pH and thermal stability. All the polysaccharides decreased the thermal and pH stability of laccase at 50 °C and 60 °C, where conjugation with gum Arabic showing the most pronounced effect. Thermal instability of gum Arabic conjugated laccase was affirmed by differential scanning calorimeter while the structural changes in the conjugated laccase responsible for thermal instability was analysed by fluorescence spectrophotometer. The gum Arabic conjugated laccase showed an unusually high tolerance to sodium chloride, thermal instability and lower stability in alkaline conditions. Gum Arabic conjugated laccase was found to decolorize Remazol brilliant blue R in the textile effluent at a slower rate without any microbial growth which was unlike that observed in effluent treated with free laccase. Further, effluent treated with conjugated laccase enabled its reuse as liquor for the dyeing to get desired shade.