Exploring dye-degrading genes azoR and yfeX in Acinetobacter spp. responsible for basic violet and reactive red dye degradation

This graphical abstract summarizes our integrated approach to the biological treatment of textile dye pollution. We first collected textile effluent and enriched and isolated dye-degrading bacteria, resulting in two promising isolates, Acinetobac ter baumannii and Acinetobacter pittii. Their dye-degradation efficiency was quantitatively assessed by spectrophotometry. We then performed Illumina whole-genome sequencing to explore the genetic basis of dye degradation. Genome analysis identified AzoR, an azoreductase associated with azo-bond cleavage, and yfeX, encoding a dye-decolorizing peroxidase involved in oxida tive degradation. Together, these findings provide a link between the observed dye-removal activity and the underlying genetic and enzymatic mechanisms, highlighting the potential of these bacteria for eco-friendly treatment of textile effluent. Rapid textile industry growth has increased azo dye pollution in aquatic ecosystems, creating ecological and health risks, while costly, inefficient conventional treatments highlight the need for sustainable bioremediation. This study aimed to isolate and characterize indigenous bacterial strains capable of degrading Basic Violet and Reactive Red dyes from textile industrial effluents, and to elucidate the genetic determinants underlying their biodegradation potential through whole-genome analysis. Effluent samples were collected and subjected to enrichment and isolation procedures. Dye degradation efficiency was quantitatively assessed by monitoring the reduction in absorbance at 590 nm (Basic Violet) and 554 nm (Reactive Red) under varying concentrations and incubation periods. Maximum degradation was observed at 150 ppm following 72 h of shaking incubation. Isolate-1 achieved 98.68% (Basic Violet) and 99.20% (Reactive Red) degradation, while Isolate-2 demonstrated 98.83 and 99.73% degradation, respectively. Whole-genome sequencing using the Illumina platform identified Isolate-1 as Acinetobacter baumannii and Isolate-2 as Acinetobacter pittii. Genome annotation revealed key dye-degrading genes, including azo reductase (azoR) and dye-decolorizing peroxidase (yfeX), confirming their enzymatic capacity for cleavage of the azo bond and oxidative degradation. The isolates demonstrated efficient laboratory-scale dye degradation and provide genomic insights into azo dye biodegradation.