Ammonium influences microbial community composition in anaerobic digestion of swine manure

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.

研究目标：揭示微生物群落在铵盐浓度梯度下的演替规律，并探究微生物群落组成与厌氧消化（Anaerobic Digestion，AD）性能之间的关联。
研究结果：甲烷（CH4）产率随铵盐浓度升高而下降，当铵盐浓度超过4000 mg/L时产率受到显著抑制。挥发性脂肪酸（Volatile Fatty Acids，VFAs）尤其是乙酸，随铵盐浓度升高发生积累。原核微生物群落的组成与结构随铵盐梯度发生显著变化。其中，梭菌属（Clostridium）、温微菌属（Tepidimicrobium）、产孢厌氧杆菌属（Sporanaerobacter）、消化链球菌属（Peptostreptococcus）、八叠球菌属（Sarcina）及胨球菌属（Peptoniphilus）对铵盐表现出良好的耐受性。而对铵盐耐受性较差的互营单胞菌属（Syntrophomonas）则可能在厌氧消化过程中受到抑制。甲烷八叠球菌属（Methanosarcina）为优势产甲烷菌。
研究结论：过量铵盐会打破酸化过程与产甲烷过程之间的耦合关联。铵盐梯度下特定类群的演替，可反映其对不同生态位的适应性，最终导致厌氧消化效率产生差异。