Microbial community structures in mixed bacterial consortia for azo dye treatment under aerobic and anaerobic conditions

► Thirteen strains that possess high MR-decolorizing ability are isolated. ► Two consortia, which could decolorize MR under aerobic or anaerobic conditions, are developed. ► PCR-DGGE is used to monitor the succession of the microbial community of the two consortia. ► Microbial populations in the aerobic consortium belong to Klebsiella, Buttiauxella and Bacillus. ► The popular genera are Klebsiella, Escherichia, Bacillus and Clostridium in anaerobic condition.