Abundance of ammonia-oxidizing bacteria and archaea under different ventilation strategies during cattle manure composting.

Composting of cattle manure was conducted under four ventilation strategies, i.e., no-aeration (A-00), continuous aeration (B-44), non-aeration for 14 d and then aeration for 42 d (C-04), aeration for 14 d and then no-aeration for 42 d (D-40). Physicochemical parameters and potential ammonia oxidation (PAO) indicated that continuous and intermittent ventilation provide favourable conditions for ammonia-oxidizing bacteria (AOB) and archaea (AOA) to oxidize ammonia. Quantitative PCR (qPCR) analysis showed AOB amoA gene abundance of all treatments on every sampling day ranged from 2.25 × 105 to 2.76 × 109copies/g, was significantly lower than that of archaeal amoA gene from 2.71 × 108 to 9.05 × 1011copies/g. There was also a significantly positive relationship between PAO rates and AOB (r2 ≥ 0.066, p < 0.05) and AOA (r2 ≥ 0.300, p < 0.05) abundance. These data suggested that ammonia oxidation is driven by both AOA and AOB in cattle manure composting.