Microbial pathways for nitrogen loss in an upland soil

Abstract

The distribution and importance of anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) have been identified in aquatic ecosystems; their role in agricultural upland soils however has not yet been well investigated. In this study, we examined spatio-temporal distributions of anammox and n-damo bacteria in soil profiles (300 cm depth) from an agricultural upland. Monitoring nitrogen (N) conversion activity using isotope-tracing techniques over the course of one year showed denitrification (99.0% N-loss in the winter and 85.0% N-loss in the summer) predominated over anammox (1.0% N-loss in the winter and 14.4% N-loss in the summer) and n-damo (0.6% N-loss in the winter) in surface soils (0-20 cm). While below 20 cm depth, N-loss was dominated by anammox (79.4 ± 14.3% in the winter and 65.4 ± 12.5% in the summer) and n-damo was not detected. Phylogenetic analysis showed that Candidatus Brocadia anammoxidans dominated the anammox community in the surface soil and Candidatus Brocadia fulgida dominated below 20 cm depth. Dissimilatory nitrate reduction to ammonium (DNRA), another nitrite reduction process, was found to play a limited role (4.9 ± 3.5%) in the surface soil compared with denitrification; below 80 cm DNRA rates were much higher than rates of anammox and denitrification. Ammonium oxidation was the main source of NO2- above 80 cm (70.9 ± 23.3%), the key influencing factor on anammox rates, and nitrate reduction (100%) was the main NO2- source below 80 cm. Considering the anammox, n-damo and denitrification rates as a whole in the sampled soil profile, denitrification is still the main N-loss process in upland soils.

Soil fertilization affects the abundance and distribution of carbon and nitrogen cycling genes in the maize rhizosphere

“…The nitrite reductase gene families (nirB, nitrite reductase (no-f), nirA, nirD) detected within the samples are responsible for catalyzing the conversion of nitrate to gaseous nitrogen (Butterbach-Bahl et al 2013;Zumft 1997) were significantly low in abundance and unaffected by the various treatments applied (Figure 2). Denitrification is the basic avenue for nitrogen loss in the agricultural soil (Igiehon et al 2018;Zhu et al 2018). Other genes involved in denitrification process are nar, nap encode enzymes that reduces NO 2 to ammonium ions as well as nrfA which serves as marker genes for the identification of microbes that mediate these processes of denitrification (Simon 2002;Welsh et al 2014).…”

Biogeochemical evidence of anaerobic methane oxidation and anaerobic ammonium oxidation in a stratified lake using stable isotopes

“…By comparison, the number of studies demonstrating the co-occurrence of n-damo and anammox processes in natural aquatic environments is limited (e.g., Shen et al, 2014;Zhu et al, 2018). More information is needed on the connection of these processes in the natural environment, in order to obtain an accurate estimation of methane fluxes to the atmosphere and to identify the factors driving and limiting the reduction of nitrate and its intermediates in lacustrine environments.…”

Vertical distribution of microbial communities and their response to metal(loid)s along the vadose zone–aquifer sediments

“…2018; Zhu et al . 2018). To date, many studies have addressed how the microbial community changes in the surface soil and shallow vadose, but little is known about the changes from the vadose zone to the deep aquifers because of the difficulty in characterization and monitoring (Lijzen et al .…”