Date Published: September 13, 2017
Publisher: Springer Berlin Heidelberg
Author(s): Xiaoliang Jiang, Yujing Wu, Guihua Liu, Wenzhi Liu, Bei Lu.
Ammonia-oxidizing archaea (AOA) and bacteria (AOB) play important roles in regulating the nitrification process in lake ecosystems. However, the relative effects of climate, catchment land use and local conditions on the sediment ammonia-oxidizing communities in lakes remain unclear. In this study, the diversity and abundance of AOA and AOB communities were investigated in ten Yangtze lakes by polymerase chain reaction (PCR), clone library and quantitative PCR techniques. The results showed that the abundances of both AOA and AOB in bare sediments were considerably but not significantly higher than those in vegetated sediments. Interestingly, AOB communities were more sensitive to changes in local environmental factors and vegetation characteristics than were AOA communities. Amongst climate and land use variables, mean annual precipitation, percentage of agriculture and percentage of vegetation were the key determinants of AOB abundance and diversity. Additionally, total organic carbon and chlorophyll-a concentrations in lake water were significantly related to AOB abundance and diversity. The results of the ordination analysis indicated that 81.2 and 84.3% of the cumulative variance for the species composition of AOA and AOB communities could be explained by the climate, land use and local factors. The climate and local environments played important roles in shaping AOA communities, whereas catchment agriculture and water chlorophyll-a concentration were key influencing factors of AOB communities. Our findings suggest that the composition and structure of sediment ammonia-oxidizing communities in Yangtze lakes are strongly influenced by different spatial scale factors.
Nitrification plays an important role as a link between nitrogen (N) inputs from anthropogenic sources and N losses by denitrification and anaerobic ammonium oxidation (Mulder et al. 1995). The rate-limiting step of nitrification, the oxidation of ammonia to nitrite, is performed by ammonia-oxidizing archaea (AOA) and bacteria (AOB) (Juretschko et al. 1998; Francis et al. 2005). Although both AOA and AOB can be detected in a wide range of aquatic habitats, their abundance varies widely (He et al. 2007). In most sediments, the abundance of AOA is greater than that of AOB (Bernhard et al. 2010; Hou et al. 2013; Shen et al. 2014). AOA and AOB have different physiological and metabolic characteristics, including their adaption to pH (Nicol et al. 2008), trophic status (Wu et al. 2010; Prosser and Nicol 2012), and ammonium concentration (Verhamme et al. 2011), leading to different community structures and activities of ammonia-oxidizing microorganisms in sediments.