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Microbial community shifts of anaerobic sludge in response to nitrate and nitrite in simultaneous denitrification and methanogenesis systems

Anaerobic sludge was exposed to an increasing gradient of nitrite/nitrate using acetate as the carbon source in order to explore its community shifts in response to nitrate and nitrite in simultaneous denitrification and methanogenesis (SDM) systems. Amplified ribosomal DNA restriction digestion analysis (ARDRA), quantitative polymerase chain reaction (qPCR) and statistical analysis of non‐metric multidimensional scaling (NMS) was used in this study. The methanogenesis was inhibited by nitrate transiently and recovered soon, whereas when it was inhibited by 200 and 400 mg N/L nitrite, it recovered after a longer time. Dominant archaea in anaerobic sludge dosed with 0‐200 mg N/L nitrite/nitrate was Methanosarcinaceae and changed to Methanosaetaceae when nitrate/nitrite was increased to 400 mg N/L. Changes of methanogenic archaea communities were influenced by carbon source limitation rather than nitrate/nitrite inhibition. The results provided biochemical and molecular biological insight into the SDM system, which could be helpful for anaerobic reactor design and performance in the SDM system. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 661–668, 2016