Bioremediation of Reactive Dyes by Bacillus megaterium and Bacillus velezensis

Background and Objective: The use of synthetic dyes in fabric re-dyeing has become widespread and is one of the major sources of environmental pollution in urban Kano, Nigeria. This research was carried out to assess the potential of bacterial species isolated from one of the major dyeing sites in Kano: The Kofar Na’isa dyeing pit in the remediation of reactive dyes. Materials and Methods: The bacterial species (Bacillus megaterium QM B1551 and Bacillus velezensis EH9) were isolated and identified from the dye-contaminated soil using dilution, pour plate and streak culture techniques. The isolated organisms were used to assess bioremediation (biosorption and bio-decolourisation) potential on dye wastewater. Results:From the results, the highest dye removal efficiency by enzymatic action and biomass biosorption was recorded after 48 hrs, at pH 11.3 and a temperature of 37°C. The dye removal by biosorption and bio-decolourisation were within the ranges of 73.2-93.4 and 29.4-84.2% for B. velezensis and 49.3-92.5 and 26.5-92.3% for B. megaterium, respectively. Dye removal increased with an increase in contact time due to the growth of new bacterial cells. Freundlich’s isotherm model was best fitted for the biosorption of the dyes with a strong linear correlation coefficient, R² ranging from 0.923-0.999 (Bacillus velezensis) and 0.909-1.000 (Bacillus megaterium). Conclusion: It was concluded that the bacterial species can be used in the effective remediation of reactive dyes, which in turn may greatly reduce environmental pollution.