Distribution and characteristic of nitrite-dependent anaerobic methane oxidation bacteria in wastewater treatment plants and agriculture fields of northern China

Nitrite-dependent anaerobic methane oxidation (n-damo) is a recently discovered biological process, which has been arousing global attention because of its potential in minimizing greenhouse gases emissions. In this study, molecular biological techniques and potential n-damo activity batch experiments were conducted to investigate the presence and diversity of M. oxyfera bacteria in paddy field, corn field, and wastewater treatment plant (WWTP) of northern China, as well as lab-scale n-damo enrichment culture. N-damo enrichment culture showed the highest abundance of M. oxyfera bacteria and positive correlation was observed between potential n-damo rate and abundance of M. oxyfera bacteria. Both paddy field and corn field were believed to be better inoculum than WWTP for the enrichment of M. oxyfera bacteria, due to their higher abundance and diversity of M. oxyfera bacteria. Comparative analysis revealed that long biomass retention time and optimum environment (low NH₄⁺ and high NO₂^- content) were suitable for the growth of M. oxyfera bacteria. In addition, the distribution and diversity of M. oxyfera bacterial might be related to geographical regions.