Ammonia‐oxidizing communities in a highly aerated full‐scale activated sludge bioreactor: betaproteobacterial dynamics and low relative abundance of Crenarchaea

Abstract

Ammonia-oxidizing bacteria (AOB) have long been considered key to the removal of nitrogen in activated sludge bioreactors. Culture-independent molecular analyses have established that AOB lineages in bioreactors are dynamic, but the underlying operational or environmental factors are unclear. Furthermore, the contribution of ammonia-oxidizing archaea (AOA) to nitrogen removal in bioreactors has not been studied. To this end, we investigated the abundance of AOA and AOB as well as correlations between dynamics in AOB lineages and operational parameters at a municipal wastewater treatment plant sampled weekly over a 1 year period. Quantitative PCR measurements of bacterial and archaeal ammonia monooxygenase subunit A (amoA) genes revealed that the bacterial homologue predominated by at least three orders of magnitude in all samples. Archaeal amoA was only detectable in approximately 15% of these samples. Using terminal restriction fragment length polymorphism analysis, we monitored AOB lineages based on amoA genes. The Nitrosomonas europaea lineage and a novel Nitrosomonas-like cluster were the dominant AOB signatures, with a Nitrosospira lineage present at lower relative abundance. These lineages exhibited strong temporal oscillations, with one becoming sequentially dominant over the other. Using non-metric multidimensional scaling and redundancy analyses, we tested correlations between terminal restriction fragment length polymorphism profiles and 20 operational and environmental parameters. The redundancy analyses indicated that the dynamics of AOB lineages correlated most strongly with temperature, dissolved oxygen and influent nitrite and chromium. The Nitrosospira lineage signal had a strong negative correlation to dissolved oxygen and temperature, while the Nitrosomonas-like (negative correlations) and N. europaea lineages (positive correlations) were inversely linked (relative to one another) to influent nitrite and chromium. Overall, this study suggests that AOA may be minor contributors to ammonia oxidation in highly aerated activated sludge, and provides insight into parameters controlling the diversity and dominance of AOB lineages within bioreactors during periods of stable nitrification.

Spatial distribution of ammonia-oxidizing bacteria and archaea across a 44-hectare farm related to ecosystem functioning

“…This is supported by recent works reporting that AOA are adapted to low-nutrient conditions (Erguder et al, 2009;Martens-Habbena et al, 2009). In addition, AOB have been shown to be the predominating ammonia oxidizers in nutrient-rich environments such as activated sludge (Wells et al, 2009) and a sewage influenced marsh (Hö fferle et al, 2010). They have also been proposed to be functionally more important in nitrogen-rich environments compared with the AOA (Di et al, 2009(Di et al, , 2010Jia and Conrad, 2009;Zhang et al, 2010).…”

Response of ammonia-oxidizing archaea and bacteria to long-term industrial effluent-polluted soils, Gujarat, Western India

“…Diversity analysis of ammonia monooxygenase α-subunit (amoA) genes revealed clear differences in AOA and AOB community patterns in response to soil contamination (Liu et al 2010;Ollivier et al 2012). Moreover, the dominant role of AOA over AOB in nitrification was found in heavy metal-polluted soils (Li et al 2009;Kelly et al 2011;Vasileiadis et al 2012), while greater role of AOB was seen in nitrification of wastewater treatment plants and soils polluted with organic amendments (Jin et al 2010;Wells et al 2009). Distinct response of AOA and AOB in nitrification was mainly attributed to their different ecological niche specialization in natural and engineered environments .…”

Disturbance and temporal partitioning of the activated sludge metacommunity

“…However, little work has focused on the ecological consequences of press (that is, prolonged) disturbances on microbial diversity and the extent of compositional versus environmental effects on ecosystem function (Allison and Martiny, 2008). Most community ecology studies in activated sludge systems have been limited to microbial diversity surveys of fullscale municipal treatment plants that are not open to experimental manipulation (Wells et al, 2009(Wells et al, , 2011Yang et al, 2011;Ye et al, 2011;Zhang et al, 2012;Saunders et al, 2013). Thus, a large knowledge gap exists with regard to activated sludge microbial community temporal variability, responses to speciesselection pressures and resilience to disturbances.…”