A metagenomic view of how different carbon sources enhance the aniline and simultaneous nitrogen removal capacities in the aniline degradation system

To cross nitrogen removal barrier, carbon sources (sodium succinate (Z1), sodium acetate (Z2) and glucose (Z3)) were applied in aniline degradation reactor to enrich heterotrophic nitrifiers and denitrifiers. The aniline was degraded almost completely and the nitrogen removal performance was improved in three systems. The total nitrogen (TN) removal efficiency of Z2 was the highest. The dominant bacteria were phylum Proteobacteria, class BetaProteobacteria, and genus Thauera (Z1, Z3), Leptothrix (Z2). Different aniline degrading bacteria, heterotrophic nitrifiers and denitrifiers were enriched, and Z2 had more high-abundance communities. Three systems followed the meta-cleavage pathway for the aniline degradation according to the genes annotation. Particularly, the contribution of each genus to nitrogen metabolism and aromatic compounds degradation in the Z2 was more evenly distributed, rather than relying mainly on the contribution of Thauera in Z1 and Z3 so that more functional genes related nitrogen metabolism and aniline degradation were more abundant in Z2.