Differential expression of clade I and II N2O reductase genes in denitrifying Thauera linaloolentis 47LolT under different nitrogen conditions.

Nitrous oxide (N2O) is a potent greenhouse gas and its reduction to dinitrogen gas by the N2O reductase (encoded by the nosZ gene) is the only known biological N2O sink. Within the nosZ phylogeny there are two major clades (I and II), which seem to have different ecological niches. However, physiological differences of nosZI and nosZII expression that may impact emissions of N2O are not well understood.

Combined removal of organic micropollutants and ammonium in reactive barriers developed for managed aquifer recharge.

Groundwater is an important drinking water resource. To ensure clean drinking water, managed aquifer recharge (MAR) could be an attractive solution when recharging with treated wastewater. The installation of reactive barriers, e.

Habitat diversity and type govern potential nitrogen loss by denitrification in coastal sediments and differences in ecosystem-level diversities of disparate N2O reducing communities.

In coastal sediments, excess nitrogen is removed primarily by denitrification. However, losses in habitat diversity may reduce the functional diversity of microbial communities that drive this important filter function. We examined how habitat type and habitat diversity affects denitrification and the abundance and diversity of denitrifying and N2O reducing communities in illuminated shallow-water sediments.

Expression of nirK and nirS genes in two strains of Pseudomonas stutzeri harbouring both types of NO-forming nitrite reductases.

Reduction of nitrite to nitric oxide in denitrification is catalysed by two different nitrite reductases, encoded by nirS or nirK. Long considered mutually exclusive and functionally redundant in denitrifying bacteria, we show expression of both genes co-occurring in Pseudomonas stutzeri. The differential expression patterns between strain AN10 and JM300 in relation to oxygen and nitrate and their different denitrification phenotypes, with AN10 reducing nitrate more rapidly and accumulating nitrite, suggest that nirS and nirK can have different roles.

Growth yield and selection of nosZ clade II types in a continuous enrichment culture of N O respiring bacteria.

Nitrous oxide (N O) reducing microorganisms may be key in the mitigation of N O emissions from managed ecosystems. However, there is still no clear understanding of the physiological and bioenergetic implications of microorganisms possessing either of the two N O reductase genes (nosZ), clade I and the more recently described clade II type nosZ. It has been suggested that organisms with nosZ clade II have higher growth yields and a lower affinity constant (K ) for N O.

Life on NO: deciphering the ecophysiology of NO respiring bacterial communities in a continuous culture.

Reduction of the greenhouse gas NO to N is a trait among denitrifying and non-denitrifying microorganisms having an NO reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect NO emissions from ecosystems. To increase our understanding of the ecophysiology of NO reducers, we determined the thermodynamic growth efficiency of NO reduction and the selection of NO reducers under NO- or acetate-limiting conditions in a continuous culture enriched from a natural community with NO as electron acceptor and acetate as electron donor.

Design and evaluation of primers targeting genes encoding NO-forming nitrite reductases: implications for ecological inference of denitrifying communities.

The detection of NO-forming nitrite reductase genes (nir) has become the standard when studying denitrifying communities in the environment, despite well-known amplification biases in available primers. We review the performance of 35 published and 121 newly designed primers targeting the nirS and nirK genes, against sequences from complete genomes and 47 metagenomes from three major habitats where denitrification is important. There were no optimal universal primer pairs for either gene, although published primers targeting nirS displayed up to 75% coverage.

Habitat partitioning of marine benthic denitrifier communities in response to oxygen availability.

Denitrification is of global significance for the marine nitrogen budget and the main process for nitrogen loss in coastal sediments. This facultative anaerobic respiratory pathway is modular in nature and the final step, the reduction of nitrous oxide (N2 O), is performed by microorganisms with a complete denitrification pathway as well as those only capable of N2 O reduction. Fluctuating oxygen availability is a significant driver of denitrification in sediments, but the effects on the overall N2 O-reducing community that ultimately controls the emission of N2 O from marine sediments is not well known.