Low C/N Ratios Promote Dissimilatory Nitrite Reduction to Ammonium in Pseudomonas putida Y-9 under Aerobic Conditions

Abstract

The biogeochemical consequences of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) have a significant influence on nitrogen (N) cycling in the ecosystem. Many researchers have explored these two pathways in soil and sediment ecosystems under anaerobic conditions. However, limited information is available regarding the influence of external environmental conditions on these two pathways in a well-defined experimental system under aerobic conditions. In this study, the impacts of the external environmental factors (carbon source, C/N ratio, pH, and dissolved oxygen) on nitrite reduction through the denitrification and DNRA routes in Pseudomonas putida Y-9 were studied. Results found that sodium citrate and sodium acetate favored denitrification and DNRA, respectively. Furthermore, neutral pH and aerobic conditions both facilitated DNRA and denitrification. Especially, low C/N ratios motivated the DNRA while high C/N ratios stimulated the denitrification, which was opposite to the observed phenomena under anaerobic conditions.

Global soil nitrogen cycle pattern and nitrogen enrichment effects: Tropical versus subtropical forests

“…This result was in line with the finding of Sotta et al (2008), who reported no correlation between C/NO 3 − and DNRA in tropical forests. Surprisingly, our analysis showed that low soil C/N ratio stimulated DNRA in tropical and subtropical forests (Figure 2j), which was consistent with the recent findings of Huang et al (2021), but inconsistent with some studies in humid tropical forests that noted lower rates of denitrification than DNRA under higher soil C/N ratios (Rütting et al, 2011; Silver et al, 2001). The negative relationship between soil C/N ratio and DNRA may be due to the fact that lower soil C/N ratio stimulates GAN process (Figure 2c) that provides the substrate NO 3 − into DNRA process.…”

Spatial and temporal conversion of nitrogen using Arthrobacter sp. 24S4–2, a strain obtained from Antarctica

“…However, strain 24S4–2 is an aerobic bacterium, and its nitrate reduction metabolism is not sensitive to oxygen. Although some aerobic bacteria have also been reported to carry out DNRA action, the mechanism is unclear, and it is thought that they may live anaerobically in the presence of nitrate ( Samuelsson, 1985 ; Huang X. et al, 2021 ). We speculate that intracellular vesicles of strain 24S4–2 play a critical role.…”

Life Detection and Microbial Biomarker Profiling with Signs of Life Detector-Life Detector Chip During a Mars Drilling Simulation Campaign in the Hyperarid Core of the Atacama Desert

“…Further, it has been described that nitrate can be driven to denitrification or to dissimilatory nitrate reduction to ammonia (DNRA) as a function of the C/N ratio or the redox potential among other factors (van der Berg et al , 2016 ; Huang et al , 2021 ; Shen et al , 2022 ). In our study, the low C/N ratios determined, as well as the trend of decreasing C/N ratio with depth ( Fig.…”