Chemotaxis, biofilm formation, and bioaccumulation-driven decolourization of reactive violet dye by <i>Pseudomonas inefficax</i>

Azo dyes are widely used synthetic colorants characterized by one or more azo (-N = N-) bonds and are major contributors to environmental pollution due to their persistence and toxicity in industrial effluents. In the present study, indigenous bacterial strains were isolated from textile wastewater and evaluated for their potential to degrade reactive violet (RV) dye. A total of fifteen isolates were obtained through enrichment, among which four strains namely, Enterobacter cloacae, Stenotrophomonas geniculata, Pseudomonas inefficax, and Stenotrophomonas maltophilia demonstrated significant dye decolourization efficiency (>75%) at 200 ppm and were selected for further studies. Among these, P. inefficax exhibited the highest decolorization efficiency (up to 86%) under optimized conditions (pH 7, 25 °C, 2% inoculum, 400 ppm dye concentration, and 150 rpm) within 48 h. Fourier-transform infrared (FTIR) analysis indicated the cleavage of azo bonds in the dye molecules after incubation. Chemotaxis, bioaccumulation, and biofilm formation assays revealed adaptive traits that enhanced bacterial interactions with dye molecules and improved degradation efficiency. To the best of our knowledge, no previous study has evaluated the degradation of RV dye by P. inefficax while simultaneously investigating chemotaxis, biofilm formation, and bioaccumulation traits associated with dye removal. Overall, this study demonstrates the metabolic versatility and significant biodegradation potential of P. inefficax, which can be used as a promising candidate for the treatment of dye-contaminated textile effluents.