Response of Microbial Community Structures and Functions of Nitrosifying Consortia to Biorefractory Humic Substances

Abstract

Biorefractory humic substances (HS) that are ubiquitously present in nitrogen-rich wastewater streams, such as landfill leachate and livestock waste after anaerobic digestion, can potentially impact nitritation–anammox processes. In this study, multiple sequencing methods (e.g., 16S rRNA sequencing, clone library analysis, and metagenome sequencing) were employed to reveal the response of nitrosifying microbiota to HS at various concentrations (0–50 mg/L). Long-term reactor operation revealed that the nitrite yield was overall stable during all of the experimental days; however, fluctuations were observed as a result of sudden HS loads. The characterization by 16S rRNA sequencing indicated a decreased abundance of the phylum Proteobacteria (from 90.8% in HS0 to 52.1% in HS50) and an increased abundance of the phylum Bacteroidetes (from 4.7% in HS0 to 35.3% in HS50) upon exposure to HS. Both 16S rRNA sequencing and metagenome sequencing revealed that the family Nitrosomonadaceae, which was dominated by the...