title: Ammonia-oxidizing archaea respond positively to inorganic nitrogen addition in desert soils.
abstract: In soils, nitrogen (N) addition typically enhances ammonia oxidation (AO) rates and increases the population density of ammonia-oxidizing bacteria (AOB), but not that of ammonia-oxidizing archaea (AOA). We asked if long-term inorganic N addition also has similar consequences in arid land soils, an understudied yet spatially ubiquitous ecosystem type. Using Sonoran Desert top soils from between and under shrubs within a long-term N-enrichment experiment, we determined community concentration-response kinetics of AO and measured the total and relative abundance of AOA and AOB based on amoA gene abundance. As expected, N addition increased maximum AO rates and the abundance of bacterial amoA genes compared to the controls. Surprisingly, N addition also increased the abundance of archaeal amoA genes. We did not detect any major effects of N addition on ammonia-oxidizing community composition. The ammonia-oxidizing communities in these desert soils were dominated by AOA as expected (78% of amoA gene copies were related to Nitrososphaera), but contained unusually high contributions of Nitrosomonas (18%) and unusually low numbers of Nitrosospira (2%). This study highlights unique traits of ammonia oxidizers in arid lands, which should be considered globally in predictions of AO responses to changes in N availability.
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA ymarusen@asu.edu.
authors.forename: Yevgeniy
authors.initials: Y
authors.lastname: Marusenko
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Ferran
authors.initials: F
authors.lastname: Garcia-Pichel
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Hall
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000235:genetics / Q000378:metabolism*; D003889:Desert Climate; D017753:Ecosystem; D009584:Nitrogen / Q000378:metabolism*; D009606:Nitrosomonas / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D012987:Soil; D012988:Soil Microbiology
chemical_list: D012987:Soil; D000641:Ammonia; D009584:Nitrogen
keywords: Thaumarchaeota; ammonia oxidation; amoA; arid land; niche differentiation; nitrogen enrichment