Responses of community structure of amoA -encoding archaea and ammonia-oxidizing bacteria in ammonia biofilter with rockwool mixtures to the gradual increases in ammonium and nitrate

Abstract

Aims: To investigate community shifts of amoA-encoding archaea (AEA) and ammonia-oxidizing bacteria (AOB) in biofilter under nitrogen accumulation process. Methods and Results: A laboratory-scale rockwool biofilter with an irrigated water circulation system was operated for 436 days with ammonia loading rates of 49-63 NH 3 g m À3 day À1 . The AEA and AOB communities were investigated by denaturing gradient gel electrophoresis, sequencing and realtime PCR analysis based on amoA genes. The results indicated that changes in abundance and community compositions occurred in a different manner between archaeal and bacterial amoA during the operation. However, both microbial community structures mainly varied when free ammonia (FA) concentrations in circulation water were increasing, which caused a temporal decline in reactor performance. Dominant amoA sequences after this transition were related to Thaumarchaeotal Group I.1b, Nitrosomonas europaea lineages and one subcluster within Nitrosospira sp. cluster 3, for archaea and bacteria, respectively. Conclusions: The specific FA in circulation water seems to be the important factor, which relates to the AOB and AEA community shifts in the biofilter besides ammonium and pH. Significance and Impact of the Study: One of the key factors for regulating AEA and AOB communities was proposed that is useful for optimizing biofiltration technology.

Microbial Community Structure of Relict Niter-Beds Previously Used for Saltpeter Production

“…3A). pH is generally to be a key parameter in defining the abundance of AOB populations in soil ecosystems [52], [53] and bioreactors [54], [55]. The niter-bed soils in group B1 were further divided into two subgroups (Fig.…”

Community structure of denitrifying and total bacteria during nitrogen accumulation in an ammonia‐loaded biofilter

“…Details of the laboratory‐scale biofilter and sample preparations have been described previously (Yasuda et al . ). In brief, 0·8 l (223 g dry weight (d.w.)) of the rockwool packing material, a mixture of mainly rockwool, polyurethane, zeolite and dried chicken faeces, from the full‐scale reactor (Yasuda et al .…”

“…Nitrogen mass balance was calculated for gas, solid (packing material) and liquid phases by using the following equations (Yasuda et al . ).where Σ N packing material initial is the amount of total nitrogen at day 0, Σ (N‐NH 3 ) gas inlet is the sum of inflow NH 3 ‐N, and N final is the sum of nitrogen in the outlet gas, that recovered in the packing material and circulation water, and sampling loss. N sampling loss is the sum of released N‐NH 3 when the valve was opened for collecting water remaining in tubes and withdrawing nitrogen as liquid and packing material samples.…”

“…The same DNA samples were used for the molecular analysis as those used in a previous study (Yasuda et al . ). From 1·0 to 3·1 g of the packing material was used, and DNA was extracted directly by the bead‐beating method described by the Watanabe et al .…”

“…In a previous study, we showed that NH 3 removal was achieved even when concentrations of NH 4 + and NO 3 − increased to as much as 683 and 1128 mmol l −1 , respectively, in the circulation water in a laboratory‐scale biofilter system packed with rockwool and intermittent water recirculation (Yasuda et al . ). The nitrogen mass balance was in accord with the above values and fluctuated up to 39% of the sum of the initial and input nitrogen during the system operation.…”