Potential of Shewanella sp. strain IFN4 to decolorize azo dyes under optimal conditions
2016
Imran, M. (University of Agriculture, Faisalabad (Pakistan). Inst. of Soil and Environmental Sciences) | Arshad, M. (University of Agriculture, Faisalabad (Pakistan). Inst. of Soil and Environmental Sciences) | Asghar, H.N. (University of Agriculture, Faisalabad (Pakistan). Inst. of Soil and Environmental Sciences) | Asghar, M. (University of Agriculture, Faisalabad (Pakistan). Dept. of Chemistry and Biochemistry) | Crowley, D.E. (University of California Riverside (USA). Dept. of Environmental Sciences)
Azo dyes are widely used by different industries including the textile industry. A substantial amount of these colorants exist in the water discharged from the textile outlets which contaminate the surrounding water bodies and soil. These colorants could be degraded by bacteria. For this purpose, thirty bacterial strains capable of degrading azo dyes were isolated from textile effluents. Strain IFN4 identified as Shewanella sp. was most efficient in decolorizing RB-5 (200 mg L-1) in mineral salt medium and color was removed greater than 90% in just four h. Decolorization efficiency of this stain was also examined using mixture of AR-81, DR-88 and RB-5 dyes and conditions were optimized for their faster degradation. Bacterium degraded the dyes mixture at all pH (5-10) and temperature (20-50 degree C) values, but with different efficiency. Maximum decolorization of the dyes mixture was recorded at pH 8.5 and at 35 degree C. Bacterium showed very fast decolorization under static incubation while negligible decolorization occurred under shaking incubation. However, bacterial growth was more under shaking than static culture. Furthermore, 10% (v/v) inoculum concentration was found to be the optimum for decolorization. The decolorization rate of Shewanella sp. strain IFN4 was very high under optimal conditions, which increased its applicability in the treatment of the wastewater.
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