Whole genome sequencing analysis and Box-Behnken design for the optimization of the decolourization of mixture textile dyes by halotolerant microbial consortium

The use of dyes in textile industries has resulted in substantially contaminated soil, water and ecosystem including fauna and flora. So, the application of eco-friendly approach for dyes removal is in great demand. The goal of this research was to develop and test a bacterial consortium for biodegrading dyes in artificial textile effluent (ATE) derived from mixture of Indigo carmine (40 mg/l); Malachite green (20 mg/l); Cotton bleu (40 mg/l); Bromocresol green (20 mg/l) and CI Reactive Red 66 (40 mg/l) dissolved in artificial seawater. The Box-Behnken design (BBD) which combine six variables with three levels each was used to determine the potential removal of dyes in ATE, by the selected microbial consortium (M31 and M69b). The experimental process indicated that decolourization of ATE reached 77.36 % under these conditions values: salinity (30 g/l), pH (9), peptone (5 g/l), inoculum size (1.5 108 CFU/ml), agitation (150 rpm) and contact time (72 h). The decolourization was confirmed by FTIR spectrum analysis of ATE before and after bacterial treatment. Bacterial strains used in this study were identified as Halomonas pacifica M31 and Shewanella algae M69b using 16 rDNA sequences. Moreover, the total genome analysis of M31 and M69b validated the implication of bacterial genes in mixture dyes removal. Therefore, the effect of the selected bacterial consortium on ATE removal was confirmed and it may be used in industrial wastewater treatment to issuing environmental safety.