Biosorption of direct textile dye Congo red by Bacillus subtilis HAU-KK01

Abstract

A total of 68 bacterial isolates were obtained from soil and effluent collected from contaminated site and screened for their ability to decolorize Congo red direct dye. Out of these, TS-1 identified as Bacillus subtilis KK01 was selected for further study based on its ability to decolorize dye efficiently with the maximum concentration and in short time. Experimental data were analyzed by applying kinetic modeling for determination of order of reaction and adsorption isotherm used to investigate the mechanism of biosorption. Predicted and experimental data were confirmed by correlation coefficients (R²) fit. Chemisorption predicted to play a key mechanism in Congo red dye biosorption. Optimization of culture conditions for maximum decolorization of the Congo red dye revealed that bacterium was able to perform best at following culture conditions viz. Sucrose, Ammonium chloride as preferred carbon and nitrogen sources, followed by suitable temperature and pH as 35 °C and neutral pH 7.0 with 1% of inoculum size. Toxicity of dye and bacterial potential to remediate Congo red dye was determined by seed germination of wheat and mungbean crops. Immobilization of bacteria on sodium alginate beads enhanced the percent decolorization that gives opportunity to use such bioagents at industrial scale.

Keywords:

• Adsorption isotherm
• decolorization
• dye
• immobilization
• toxicity

Acknowledgments

Authors are thankful to Head of Department of Microbiology for providing necessary facilities. This research work presented is part of Ph.D. program and further research carried out at CCS HAU, Hisar, India. The authors have no conflict.