Immobilization Of Bacillus subtilis For Improved Decolourization Of Congo Red Compared To Free Cells

IJEP 41(5): 495-502 : Vol. 41 Issue. 5 (May 2021)

Shalini and Y. Pydi Setty*

National Institute of Technology, Department of Chemical Engineering, Warangal – 506 004, Telangana, India


A large amount of congo red (CR) has been discharged into the environment, mostly from the textile industries. The current study aims to find out the potential approach of congo red (CR) dye decolourization using suspended and immobilized B. subtilis. The effect of parameters (dye concentration, pH and temperature) on dye decolourization using suspended cells was studied. The corresponding cell mass (OD600) alongwith the decolourization profile, was considered to understand the effect of cell mass. B. subtilis immobilized on polyurethane foam (PUF) cubes (size: 1 cm3) have chosen to investigate the decolourization efficiency. SEM results revealed the porous structure of PUF and layer formation. The FTIR analysis was employed to confirm the decolourization. The maximum decolourization of 92% was achieved by immobilization method within 6 hr, whereas suspended cell assisted decolourization showed 82% within 12 hr. The data confirmed the second-order decolourization kinetics. We have found that the reaction rate and reaction rate constant (k) was found to be higher for immobilized cell assisted decolourization. The characteristic azo peaks have not found in FTIR samples of immobilized decolourization. The results confirmed that immobilization of B. subtilis is an efficient method for CR decolourization compared to the suspended cells.


Bacillus subtilis, Congo red, Immobilization on polyurethane foam, microbial assisted decolourization


  1. Chung, K. T. and C.E. Cerniglia. 1992. Mutagenicity of azo dyes : Structure-activity relationships. Mutat. Res./Reviews Mutat. Res., 277 (3):201-220.
  2. Lade, H., et al. 2015. Mineralization and detoxification of the carcinogenic azo dye Congo Red and real textile effluent by a polyurethane foam immobilized microbial consortium in an upflow column bioreactor. Int. J. Env. Res. Public Health. 12:6894-6918.
  3. Novotny’, C., et al. 2004. Biodegradation of synthetic dyes by irpex lacteus under various growth conditions. Int. Biodeterior. Biodegrad., 54:215-223.
  4. Mittal, A., et al. 2014. Process development for the removal of hazardous anionic azo dye Congo Red from wastewater by using hen feather as potential adsorbent. Desalin. Water Treat., 52:227-237.
  5. Cheng, Z., et al. 2015. Adsorption behaviour of Direct Red 80 and Congo Red onto activated carbon/surfactant: Process optimization, kinetics and equilibrium. Spectrochim Acta A : Mol. Biomol. Spectrose. 137:1126:1143.
  6. Guy, N., et al. 2016. Comparison of palladium/zinc oxide photocatalyst prepared by different palladium doping methods for Congo Red degradation. J. Colloid Interface Sci., 466:128-137.
  7. Solano, A.M.S., et al. 2015. Degradation of acidic aqueous solutions of the diazo dye Congo Red by photo-assisted electrochemical processes based on Fenton’s reaction chemistry. Appl. Catal. B. Env., 168-169:559-571.
  8. Das, R., et al. 2017. Sonocatalytic rapid degradation of Congo Red dye from aqueous solution using magnetic Fe0/polyaniline nano-fibres. Ultrason. Sonochem., 37:600-613.
  9. Singh, R.L., P.K. Singh and R.P. Singh. 2015. Enzymatic decolourization and degradation of azo dyes-A review. Int. Biodeterior. Bioodegrad., 104:21-31.
  10. Bosco, F., C. Mollea and B. Ruggeri. 2017. Decolourization of Congo Red by phanerochaete crysosporium : The role of biosorption and biodegradation. Env. Tech., 38:2581-2588.
  11. Wang, N., et al. 2017. Decolourization and degradation of Congo Red by a newly isolated white rot fungus, Ceriporia lacerata from decayed mulburry branches. Int. Biodeterior. Biodegrad., 117:236-244.
  12. Abu, T. M., et al. 2018. Bioremediation of Congo Red dye in immobilized batch and continuous packed bed bioreactor by Brevibacillus parabrevis using coconut shell bio-char. Bioresour. Tech., 252:37-43.
  13. Chaieb, K., M. Hagar and N.R.E. Radwan. 2016. Biodegradation and decolourization of azo dyes by adherent Staphylococcus lentus strain. Appl. Biol. Chem., 59:405-413.
  14. Loncar, N., et al. 2014. Congo Red degrading laccases from Baccillus amyloliquefaciens strains isolated from salt spring in Serbia. Int. Biodeterior. Biodegrad., 91:18-23.
  15. Chengalroyen, M.D. and E.R. Dabbs. 2013. The microbial degradation of azo dyes : Mini review. World J. Microbial. Biotech., 29:389-399.
  16. Gopinath, K.P., et al. 2009. Bacillus sp. mutant for improved biodegradation of Congo Red. Random mutagenesis approach. Bioresour. Tech., 100:6295-6300.
  17. Hameed, B.B. and Z.Z. Ismail. 2018. Decolouri-zation, biodegradation and detoxification of reactive red azo dye using non-adapted immobilized mixed cells. Biochem. Eng. J., 137:71-77.
  18. Tan, L., et al. 2014. Aerobic decolourization and degradation of azo dyes by suspended growing cells and immobilized cells of a newly isolated yeast Magnusiomyces ingens LH-F1. Bioresour. Tech., 158:321-328.
  19. Silveira, E., et al. 2011. Decolourization of industrial azo dye in an anoxic reactor by PUF immobilized Pseudomonas oleovorans. J. Water Resuse Desalin., 1:18-26.
  20. Barraga’n, B.E., C. Costa and M. C. Ma’rquez. 2007. Biodegradation of azo dyes by bacteria inoculated on solid media. Dyes pigments. 73-81.
  21. Padmanaban, V.C., et al. 2016. Kinetic studies on degradation of Reactive Red 120 dye in immobilized packed bed reactor by Bacillus cohnii RAPTI. Bioresour. Tech., 213:39-43.
  22. Agrawal, S., et al. 2017. Baterial decolourization : Degradation and detoxification of azo dyes : An eco-friendly approach. Springer, Cham., pp 91-124.
  23. Meerbergen, K., et al. 2018. Isolation and screening of bacterial isolates from wastewater treatment plants to decolourize azo dyes. J. Biosci. Bioeng., 125:448-456.
  24. Li, R., et al. 2015. Decolourization and biodegradation of the Congo Red by Acinetobacter baumannii YNWH 226 and its polymer production’s fluocc-ulation and dewatering potential. Bioresour. Tech., 194:233-239.
  25. Bartošova’, A., et al. 2017. Usage of FTIR-ATR as non-destrative analysis of selected toxic dyes. Res. Papers Faculty Mater. Sci. Tech. Slovak Univ. Tech., 25(40):103-111.