Microbiome comparisons reveal the core microorganisms and key nitrogen metabolic pathway involved in industrial nitrogen fertilizer wastewater treatment plants

Microbiomes from municipal wastewater treatment plants (WWTPs) have been widely investigated, but less attention has been paid to those in the industrial WWTPs. To compare the microbiomes involved in nitrogen fertilizer wastewater treatment, four WWTPs with different concentrations and types of pollutants, processes, and geographic locations were chosen. Diversity results revealed that microbial community was similar within the same WWTP, but different among the four WWTPs. CPCoA further demonstrated these differences (P = 0.022), implying that the diverse manufactured products acted as electron donors to create distinct ecological niches for denitrification. However, bacterial composition and functional profile were similar among four WWTPs (P > 0.05), and their abundance differed and fluctuated. More than 80 % of the dominant genera detected were present in all four WWTPs. And the core bacteria identified were Hyphomicrobium, Acinetobacter, Pedomicrobium, Methyloversatilis, Gp16, Thauera, and Moorella respectively, accounting for 19.524 % of total bacterial abundance. Forty-five nitrogen metabolism genes were active in four nitrogen cycle pathways (nitrification, assimilatory nitrate reduction, dissimilatory nitrate reduction, denitrification). The key genes were amoC (0.30 %), nasA (5.35 %), nirA (2.17 %), nirB (6.04 %), nirD (5.82 %), narG (3.87 %), narH (4.65 %), nirK (3.90 %), norB (3.32 %), nosZ (2.80 %). Hyphomicrobium, Thauera, Afipia, and Paracocccus were the hosts of denitrification genes, synergistically treating the nitrogen fertilizer wastewater to meet the discharge standard. These results suggested that microbial community structure in the nitrogen fertilizer industry is similar, helping further the understanding of the microbiota at an industry level though more samples are required to verify this.