Microbial degradation of azo dyes by textile effluent adapted, Enterobacter hormaechei under microaerophilic condition

Landmark and sustainable eco-friendly dye treatment processes are highly desirous to ameliorate their effect on the environment. The present study investigated the azo dye degradation efficiency of adapted Enterobacter hormaechei SKB 16 from textile effluent polluted soil in optimized culture conditions. The adapted bacteria strain was identified by standard microbiological and molecular techniques. E. hormaechei was tested individually for the decolourizing of Reactive Yellow 145 (RY 145) and Reactive Red F3B (RR 180) dyes under optimized conditions of pH, temperature and dye concentration on decolourization were studied. The adapted bacteria strain exhibited maximum decolourization (98 %) of Reactive yellow 145 and Reactive red 180 in 100 ppm concentration at pH 7, temperature 37 degrees C after 98 h of incubation. The enzyme analyses revealed that azo reductase and laccase played major roles in the cleavage of the azo bond and desulfonation respectively of both dyes during degradation. The metabolites were further characterized by Fourier Transform Infrared Spectroscopy (FT-IR), High-Performance Liquid Chromatography (HPLC), and Gas Chromatography-Mass Spectrometry (GC-MS). Thereafter, degradation was deduced based on changes of the functional group, variation in retention times and mass/charge ratio and molecular weight. This study elucidated the promising potentials of adapted SKB 16 strain in the eco-friendly removal of textile azo dyes. In addition, repeatability and sustainability are enhanced due to effective management of time which would have been spent on rigorous and extensive screening process.

Automated summary

This study investigated the azo dye degradation efficiency of adapted Enterobacter hormaechei SKB 16 strain from textile effluent polluted soil, and identified the major roles of azo reductase and laccase enzymes in decolourization. The metabolites were characterized using FT-IR, HPLC, and GC-MS, showing promising potentials for eco-friendly removal of textile azo dyes.