Growth yield and selection of nosZ clade II types in a continuous enrichment culture of N 2 O respiring bacteria

摘要: Nitrous oxide (N2 O) reducing microorganisms may be key in the mitigation of N2 O emissions from managed ecosystems. However, there is still no clear understanding physiological and bioenergetic implications possessing either two reductase genes (nosZ), clade I more recently described II type nosZ. It has been suggested that organisms with nosZ have higher growth yields a lower affinity constant (Ks ) for O. We compared communities different nosZI/nosZII ratios selected chemostat enrichment cultures, inoculated activated sludge, fed as sole electron acceptor limiting factor acetate donor. From sequencing 16S rRNA gene, FISH quantitative PCR nir genes, we concluded betaproteobacterial denitrifying dominated enrichments members within family Rhodocyclaceae being highly abundant. When comparing cultures ratios, did not find support (i) energy conserving respiration pathway systems, reflected yield per mole substrate, or (ii) O, defined by μmax /Ks , II.