Efficacy of bacterial strains isolated from textile wastewater for degradation of azo dye associated aromatic amines

Abstract

Wastewater from textile processing and dyestuff manufacturing industries contains different kinds of dyes and their metabolites, which are mutagenic and carcinogenic in nature. Such wastewater should be treated in order to avoid ground and surface water contamination. The aim of present research was to isolate such bacterial strains which are capable of degrading dye-originated aromatic amines. Ten samples of wastewater and sludge were collected from outlets and wastewater streams of different textile industries. The analysis of wastewater showed a wide variation in the pH (8.10-12.3), total dissolved solids (500-20100 mg L-1) and chemical oxygen demand (125-556 mg L-1). A total of 256 bacterial isolates were collected through enrichment of the mineral salt medium with an aromatic amine, 4-nitroaniline (100 μmol L-1), and dyes (100 mg L-1) using 10 mL wastewater/sludge as inoculum source. Based on ability to degrade 4-nitroaniline most efficient bacterial strain was identified as Raoultella planticola (IL11) through 16S rRNA gene analysis. These findings suggest that the indigenous bacterial strains have potential for bioremediation of dye-containing textile effluents, and for complete mineralization, 4-nitroaniline degrading strains may be used in combination with dye degrading strains.