Biodegradation of textile azo dyes by textile effluent non-adapted and adapted Aeromonas hydrophila

Abstract

Textile effluent discharged in water and soil have severe effects on living beings as well as environs worldwide. Pioneering, ecologically sustainable and economically viable treatment systems are urgently desired. This study investigated decolorization along with degradation of three azo dyes by non-adapted Aeromonas hydrophila MTCC 1739 and textile-effluent adapted Aeromonas hydrophila SK16 bacteria under optimized physicochemical conditions. UV–visible analysis (for decolorization percentage calculated using absorbance), FTIR (fourier transform infrared spectroscopy for functional group identification), HPLC (high performance liquid chromatography for degraded metabolites analysis based on retention time) and GC-MS (gas chromatography-mass spectrometry for proposing degradative pathways based on mass/charge as well as molecular weight) supported efficient biodegradation of these dyes into simpler metabolites by both cultures. Time taken for decolorization by the adapted strain was less but both were equally efficient in mineralizing dyes, utilizing them as energy source. Enzyme assays revealed over-expression of dye degrading enzymes in presence of toxic azo dyes. Thus, it is suggested that both adapted and non-adapted bacteria act as azo dye degraders with potential use in efficient and lucrative effluent treatment curbing expansive preliminary screening of autochthonous strains for azo dye degradation.