The short- and long-term effects of environmental conditions on anaerobic methane oxidation coupled to nitrite reduction

Anaerobic oxidation of methane coupled to nitrite reduction (n-damo) plays an important role in global carbon and nitrogen cycles and also is a potential bioprocess in wastewater treatment. In this work, the effects of environmental conditions – temperature, pH and salinity – on the metabolic activity and growth rate of n-damo bacteria were investigated by short-term batch test and long-term bacterial incubation. Quantitative PCR and 16S rRNA and pmoA gene sequencing were applied to detect the microbial community in the long-term incubation. The results indicated that all the three environmental factors significantly affected the metabolic activity and growth rate of n-damo bacteria and the optimum temperature, pH and salinity were 35 °C, 7.6 and 0 g NaCl L⁻¹, respectively. Notably, salinity adaption of n-damo bacteria was first observed under salinity stress of 20 g NaCl L⁻¹. It's predicted that n-damo process might occur in saline environments and future work could focus on this.