Identifying the process niche of complete ammonia oxidizing bacteria

摘要

The discovery of the complete ammonia oxidizing (comammox) bacteria, contradicts the long-held dogma that ammonia and nitrite oxidation are catalyzed separately by ammonia oxidizing bacteria (AOB) or archaea (AOA), and nitrite oxidizing bacteria (NOB), respectively. This finding raises new questions about the contribution of comammox bacteria towards ammonia oxidation in full-scale nitrogen removal systems. We have conducted a sampling campaign at multiple nitrogen removal systems with varying process configurations to identify process configurations and environmental conditions under which comammox bacteria contribute significantly to ammonia oxidation. Metagenomic analysis revealed that comammox were present in most of the nitrification-denitrification systems and qPCR analysis demonstrated that comammox bacteria dominate in systems with high solids retention time and are particularly important in systems that incorporate Integrated Fixed-Film Activated Sludge (IFAS).