N-acyl-_L-homoserine lactones release and microbial community changes in response to operation temperature in an anammox biofilm reactor

Lingjie Liu, Min Ji, Fen Wang, Zhongke Tian, Zhao Yan, Shuya Wang

School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China.

Abstract

A 1 L lab-scale anaerobic ammonium oxidation (anammox) biofilm reactor with nitrogen loading rate of 0.11 g/L d was run for 110 days with the operation temperature declining from 36°C to 15 °C. The total inorganic nitrogen removal efficiency showed a reduction from 80% to 66%, when the temperature declined from 36°C to 15°C. N-acyl-_L-homoserine lactones (AHLs) concentrations, especially C8-HSL and C6-HSL, declined in both water and biomass phases, and this decline indicated that the quorum sensing weakened. Microbial community analysis revealed that Candidatus Kuenenia was the predominant anammox bacteria during the entire operating period. The abundance of Candidatus Kuenenia increased from 1.43% to 22.89% when the temperature decreasing from 36°C to 15°C. The correlation between microbial genus and AHLs was complicated. Overall, the temperature decrease weakened the quorum sensing so that the nitrogen removal performance deteriorated, and increasing the anammox activity might be an efficient way to improve performance.

Keywords: Anammox, Temperature, Quorum sensing, Microbial community analysis.