Molecular mechanisms involved in reductive decolorization of azo dyes are unclear, especially in the presence of sulfate. We aim to investigate the microbial communities and their roles in the biodegradation of a model azo dye in a two-stages anaerobic digestion system fed with wastewater containing azo and sulfate. The acidogenic reactor was designed so that it could uptake high loads of dye and achieve near complete decolorization. This was accomplished by inhibiting sulfidogenesis and methanogenesis due to the low pH of this unit, so electrons from the co-substrate could be preferentially used to reduce azo compounds. Microbial biomass has been collected periodically and will be analyzed using 16S metabarcoding and shotgun metagenomics. We also propose to use differential coverage binning to recover high quality genomes from the sequenced metagenomes. Quantitative proteomics will be further employed to identify proteins putatively involved in the degradation of the azo dye. We hope that this integrated approach will broaden our understanding of the molecular mechanisms involved in the biodegradation of azo dyes and provide support to the design of treatment units that suit the needs of different types of wastewaters containing azo dyes.
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