A Dual Enrichment Strategy Provides Soil- and Digestate-Competent Nitrous Oxide-Respiring Bacteria for Mitigating Climate Forcing in Agriculture.

Manipulating soil metabolism through heavy inoculation with microbes is feasible if organic wastes can be utilized as the substrate for growth and vector as a fertilizer. This, however, requires organisms active in both digestate and soil (generalists). Here, we present a dual enrichment strategy to enrich and isolate such generalists among NO-respiring bacteria (NRB) in soil and digestates, to be used as an inoculum for strengthening the NO-reduction capacity of soils.

Genotypic and phenotypic characterization of hydrogenotrophic denitrifiers.

Stimulating litho-autotrophic denitrification in aquifers with hydrogen is a promising strategy to remove excess NO , but it often entails accumulation of the cytotoxic intermediate NO and the greenhouse gas N O. To explore if these high NO and N O concentrations are caused by differences in the genomic composition, the regulation of gene transcription or the kinetics of the reductases involved, we isolated hydrogenotrophic denitrifiers from a polluted aquifer, performed whole-genome sequencing and investigated their phenotypes. We therefore assessed the kinetics of NO , NO, N O, N and O as they depleted O and transitioned to denitrification with NO as the only electron acceptor and hydrogen as the electron donor.

Complete Genome Sequences of Hydrogenotrophic Denitrifiers.

Hydrogenotrophic denitrifiers are important bacteria for nitrate removal in wastewater and aquifers. Here, we report the complete genome sequences of three hydrogenotrophic denitrifiers, namely, Dechloromonas denitrificans strain D110, Ferribacterium limneticum strain F76, and Hydrogenophaga taeniospiralis strain H3, all of which were isolated from a nitrate-polluted aquifer in Bavaria (Germany).

Strategies to Overcome Intermediate Accumulation During Nitrate Remediation in Groundwater by Hydrogenotrophic Denitrification.

Bioremediation of polluted groundwater is one of the most difficult actions in environmental science. Nonetheless, the clean-up of nitrate polluted groundwater may become increasingly important as nitrate concentrations frequently exceed the EU drinking water limit of 50 mg L, largely due to intensification of agriculture and food production. Denitrifiers are natural catalysts that can reduce increasing nitrogen loading of aquatic ecosystems.

Denitrifying pathways dominate nitrous oxide emissions from managed grassland during drought and rewetting.

Nitrous oxide is a powerful greenhouse gas whose atmospheric growth rate has accelerated over the past decade. Most anthropogenic NO emissions result from soil N fertilization, which is converted to NO via oxic nitrification and anoxic denitrification pathways. Drought-affected soils are expected to be well oxygenated; however, using high-resolution isotopic measurements, we found that denitrifying pathways dominated NO emissions during a severe drought applied to managed grassland.