Biosorption isotherm and composition of Amido black 10B decolorizing metal and salt tolerant bacterial consortium

The biological decolorization offers an eco-friendly solution for the treatment of azo-dye effluents from various industries. This study reports the decolorization, biosorption, and community composition of Amido Black 10B (AB) degrading bacterial consortium. The consortium achieved 72–75 % decolorization of AB in 24 h at 2000 mg/L concentration under static conditions and in the presence of heavy metals, NaCl, sucrose, and alkaline pH. Exposure to metals, sucrose, salts, and AB induced intracellular proline production. The decolorized dye showed a loss of toxicity to cyanobacteria. The dried biomass of the consortium stored for four years retained the decolorization activity. 16S rRNA metagenome analysis revealed the dominance of Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria at the phylum level. The predictive functional profile exhibited many KEGG IDs and COG categories of enzymes belonging to the xenobiotic and metabolism pathway. The dye biosorption data was best described by the Freundlich isotherm model. The calculated thermodynamic parameters ΔGº, ΔHº, and ΔSº were all estimated to be positive. This suggests that the dye adsorption process is non-spontaneous and indicates an increase in randomness at the bacterial cell surface. The result exhibits the dye detoxification and biosorption mechanism of the AB-degrading bacterial consortium.