TABLE 1.
Distribution of ammonia-oxidizers in different ecosystems.
| Country | Ecosystem | AOA | AOB | comammox Nitrospira clade A | comammox Nitrospira clade B | References |
| America | Recirculating aquaculture systems | 0.94 × 108–3.4 × 108 (copies/g) | 2.6 × 103–5.0 × 105 (copies/g) | 1.6 × 108–4.2 × 108 (copies/g) | – | Bartelme et al., 2017 |
| Denmark | Drinking water | 1.2 × 103–3.4 × 103 (copies/m3) | 1.6 × 107–10.0 × 107 (copies/m3) | 0.82 × 108–2.58 × 108 (copies/m3) | – | Tatari et al., 2017 |
| Austria | Waste water treatment plant | – | 1.3 × 103–2.1 × 103 (copies/ng DNA) | 3.4 × 102–6.8 × 102 (copies/ng DNA) | – | Pjevac et al., 2017 |
| China | Overlying water in river | 3.34 × 103–2.18 × 107 (copies/L) | 1.06 × 105–2.98 × 107 (copies/L) | 1.25 × 104 (copies/L) | – | Zhang et al., 2019 |
| China | Agriculture soil | – | – | 4.14 × 104–1.65 × 107 (copies/g) | 9.44 × 102–2.12 × 106 (copies/g) | Xu et al., 2020 |
| Italy | Rice paddy soil | 2.1 × 103–3.1 × 103 (copies/ng DNA) | – | 3.6 × 102–4.6 × 102 (copies/ng DNA) | 3.5 × 102–4.5 × 102 (copies/ng DNA) | Pjevac et al., 2017 |
| Italy | Forest soil | 1.4 × 102–2.6 × 102 (copies/ng DNA) | 1.7 × 103–3.5 × 103 (copies/ng DNA) | – | 2.9 × 102–4.9 × 102 (copies/ng DNA) | Pjevac et al., 2017 |
| China | River sediment | 1.84 × 102–3 × 102 (copies/ng DNA) | 9.3 × 101–3.4 × 103 (copies/ng DNA) | 1.8 × 102–2.8 × 102 (copies/ng DNA) | – | Zhao et al., 2019 |
| China | Intertidal sediment | 1.7 × 102–4.9 × 103 (copies/ng DNA) | 2.2 × 102–5.4 × 103 (copies/ng DNA) | 1.6 × 102–3.2 × 102 (copies/ng DNA) | – | Zhao et al., 2019 |
| China | Estuary tidal wetland sediment | 1.15 × 106–1.66 × 107 (copies/g) or 5.71 × 101–6.27 × 103 (copies/ng DNA) | 1.76 × 105–1.73 × 107 (copies/g) or 1.05 × 101–1.57 × 103 (copies/ng DNA) | 4.15 × 105–6.67 × 106 (copies/g) or 2.74 × 101–7.02 × 102 (copies/ng DNA) | 6.28 × 105–4.01 × 106 (copies/g) or 1.1 × 102–2.65 × 102 (copies/ng DNA) | This study |