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Objectives：To reveal the shift of microbial communities along ammonium gradients, and to examine the relationship between microbial community composition and the AD performance.Results: The CH4 production declined with increasing ammonium concentration, and was inhibited when ammonium exceeded 4000 mg/L. The VFAs especially acetate accumulated with elevated ammonium. The prokaryotic community composition and structure varied along the ammonium gradients. In particular, genera Clostridium, Tepidimicrobium, Sporanaerobacter, Peptostreptococcus, Sarcina and Peptoniphilus showed good tolerance to ammonium. However, Syntrophomonas with poor tolerance to ammonium may be inhibited during anaerobic digestion. Methanosarcina was the dominant methanogen. Conclusions: Excessive ammonium would decouple the linkage between acidification and methanogenesis. The shift of specific taxa under ammonium gradients may reflect their adaptations to different niches, which finally results in different efficiency in anaerobic digestion. |