Presence of diverse nitrate‐dependent anaerobic methane oxidizing archaea in sewage sludge

Aim The aim of this study was to explore the community diversity and abundance of nitrate‐dependent anaerobic methane oxidizing archaea, Candidatus Methanoperedens nitroreducens, in sewage sludge from wastewater treatment plants. Methods and Results Seasonal sampling of the sewage sludge was carried out from two wastewater treatment plants (WWTPs) located in the northern and southern parts of China. Through amplicon sequencing using our newly designed primers, a large number of Candidatus Methanoperedens nitroreducens‐like (M. nitroreducens) archaeal sequences (638 743) were generated. These sequences were assigned into 742 operational protein units (OPUs) at 90% cut‐off level and classified as Group B member of M. nitroreducens archaea in the phylogenetic tree. More than 80% of the OPUs were not shared between these two WWTPs, showing the M. nitroreducens‐like archaeal community in each WWTP was unique. Quantitative PCR assays also confirmed the presence of M. nitroreducens‐like archaea and revealed a higher abundance in autumn and winter than other seasons, indicating that the environmental attributes in these seasons might favour the growth of this archaea. Further redundancy analysis revealed that volatile solid and pH were the significant environmental attributes (P