“…Therefore, functional genes such as those encoding the key enzymes involved in ammonia oxidation have been considered as the alternatives for ecological studies (Rotthauwe et al, 1997). Ammonium is first oxidized by the membrane-bound enzyme ammonia monooxygenase (AMO) in β-AOB and AOA (Junier et al, 2010), so the amoA gene has been widely used for the study of diversity, abundance and distribution of AOA and β-AOB communities in diverse environments, such as lakes (Hou et al, 2013a;Hou , et al, 2013b;Vissers et al, 2013), sediments (Cao et al, 2011b;Zheng et al, 2013), wetlands (Sims et al, 2012a;Sims et al, 2012b), sponges (Han et al, 2013, paddy soils (Wang et al, 2014a), and reservoirs (Wang et al, 2014b). Hence, we used amoA gene to investigate seasonal and spatial distribution of ammonia oxidizer communities.…”