The effects of non-metallic organic tanning agents on the microbial community structure in wastewater

Non-metallic organic tanning agents were used during the leather processing, most of them will be combined with the collagen converted it into leather. But there still some of its components were discarded into the wastewater and caused serious environmental problems. In this study, the structure character of microbial communities in leather wastewater containing non-metallic organic tanning agents and the effect of the leather wastewater on the ecology of the microorganisms were studied with the high-throughput sequencing. The results show that the presence of 1,657, 49 bacterial and fungal OTUs (Operational Taxonomic Unit), at 97% similarity level. Significant differences on microbial community composition in wastewater were observed in systems containing different non-metallic organic tanning agents. The Firmicutes and proteobacteria were dominated bacteria in T1, T3, T8, KB and T6. Ascomycota and Basidiomycota were the most richness fungi in T1, T3, T6, T8 and KB. The relative abundance of dominant bacteria pseudodomonas was significantly positively correlated with TN, NH3, and TOC (0.01 < P ≤ 0.05). The relative abundance of dominant bacteria Terrisporobacter and Ruminococcus_1 was positively correlated with pH (0.01 < P ≤ 0.05). The relative abundance of the dominant bacteria norank_o_JG30_KF_CM45 was positively correlated with TP (0.001 < P ≤ 0.01). The relative abundance of dominant bacteria Acidocella and Mycobacterium was significantly positively correlated with NO3 (P ≤ 0.001). In contrast, the relative abundance of norank_f_Elev_16S_1332 was negatively correlated with TN (0.01 < P ≤ 0.05). The relative abundance of norank_o_JG30_KF_CM45 was negatively correlated with NH3 (0.01 < P ≤ 0.05) and TOC (0.001 < P ≤ 0.01). The relative abundance of pseudomonas was negatively correlated with pH and TP (0.01 < P ≤ 0.05). Pseudomonas, Clostridium, Turicibacter, Acidocella, Intestinibacter, and Bacillus are highly tolerant bacteria in non-metallic organic tanning agents wastewater. These highly tolerant microorganisms should be actively explored for bioremediation of non-metallic organic tanning agents wastewater.