Prospective assessment of the Enterobacter aerogenes PP002 in decolorization and degradation of azo dyes DB 71 and DG 28

The aim of the present study focused on the bacteriological decolourization and degradation of azo dyes Direct Blue 71 and Direct Green 28. The dye decolorizing and degrading proficient bacterial strain was isolated from the textile effluent tainted soil sample. The strain was identified as Enterobacter aerogenes (GenBank: KP770134.1) based on 16S rRNA sequencing. The influence of various culture conditions such as pH, temperature, agitation and concentration of dyes on the rate of decolorization were studied. The strain has shown the remarkably higher percentage of decolorization at 100 mg L−1 concentration, 37 °C, pH 7 and 168 h of incubation period for both dyes. Physicochemical properties of textile effluent were examined before and after treatments. The results emphasized that there was a remarkable reduction in BOD, COD, TS and TSS after degradation. The UV-vis, HPLC and FTIR analysis of metabolites after treatment confirmed that the decolorization was due to degradation. The adsorption kinetics was analyzed using zero-, first-, second-order and intra-particle diffusion models. It was found that the decolorization followed zero-order kinetic reaction with regard to the intra-particle diffusion. The phytotoxicity studies of control dye and degraded metabolites were tested. The phytotoxicity results divulge that the degraded metabolites have no adverse effects and it can be used for safe irrigation.