The Contribution of Nitrate Dissimilation to Nitrate Consumption in narG - and napA -Containing Nitrate Reducers with Various Oxygen and Nitrate Supplies

Abstract

Nitrate reducers containing narG or napA are ubiquitous, but little is known about their functional performance in various environments. Our study provides an important clue that the nitrate consumption of narG -containing strains is mainly caused by dissimilatory reduction in the environments, while that of napA -containing nitrate reducers under anaerobic conditions is ascribed to nitrate dissimilation but under the aerobic condition is attributed to the assimilation by cell growth.

Predicted metabolic roles and stress responses provide insights into candidate phyla Hydrogenedentota and Sumerlaeota as members of the rare biosphere in biofilms from various environments

“…Genes involved in nitrate import and reduction were present in MAG 30 (Table S1 ). Recent studies have revealed the role of napA in dissimilatory nitrate reduction under anaerobic conditions indicating that MAG 30 may perform dissimilatory reduction of nitrate to nitrite (Alcántara‐Hernández et al, 2009 ; Chen et al, 2022 ). Moreover, the presence of nir genes indicates the denitrifying capabilities of this Sumerlaeota MAG.…”

Bacterial denitrification drives elevated N 2 O emissions in arid southern California drylands

“…Desert soils can support denitrifier communities (11,(30)(31)(32), and wetting soils following experimental drought can stimulate denitrification (19,20). Because we did not detect napA transcripts, it is possible that narG denitrifiers are better suited to remain active in hot and dry environments (33)(34)(35) to take advantage of resources flushed during brief anoxic periods after wetting (36)(37)(38)(39)(40)(41). While detecting narG transcripts does not conclusively demonstrate that biological processes were reducing NO 3…”