Microbial decolorization of Methyl Orange by Klebsiella spp. DA26

Abstract

Synthetic dyes have increasingly been used in the textile and dyeing industries because of their ease and cost-effectiveness in synthesis, firmness, high stability to light, temperature, detergent and microbial attack and variety in color compared with natural dyes. This has resulted in the discharge of highly polluted effluents. physicochemical treatment methods are not economically feasible as they produce large volume of sludge. Besides the conventional physico-chemical methods, microbial degradation of azo dyes has been attracted significant attention. In present study methyl Orange as an azo dye was used for biodegradation study by using indigenous bacterial isolates from contaminated soil. The potent decolorizing bacterial strain, was isolated and screened for dye decolorization and identified as Klebsiella spp. DA26 on the basis of morphology, cultural and biochemicals and further 16s rRNA sequencing was carried out. In Phlogenetic tree, isolate had shown 95% similarity with Klebsiella oxytoca. The isolate had showed 86.9% decolorizing activity under optimized condition through a degradation mechanism rather than adsorption as seen by decrease in peak at 530nm within 48 hrs. In presence of penicillin and Chloramphenicol- 61.68% and 14.83% dye decolorization was seen. The Rf values 0.79 and 0.85 for the dye degraded products and 0.93 for parental dye compound was observed during TLC of biodecolorized broth. In FTIR spectra of biodecolorized broth, absence of peaks at 1600.92/cm and 1517.98/cm indicate stretching of –C=C- aromatic skeletal bond and –N=N– bond. On ANOVA test, all the data obtained was significant at 0.5% level. The toxicity of dye and degraded products is under study. These observations has established that the bacteria are adaptive in nature and can degrade dye contaminants. The novel dye degrading bacterial isolate has been isolated. However, potential of the strain needs to be demonstrated for its application in treatment of real dye bearing waste waters using appropriate bioreactors.