Expanded metabolic versatility of ubiquitous nitrite-oxidizing bacteria from the genus Nitrospira.
Nitrospira are a diverse group of nitrite-oxidizing bacteria and among the environmentally most widespread nitrifiers. However, they remain scarcely studied and mostly uncultured. Based on genomic and experimental data from Nitrospira moscoviensis representing the ubiquitous Nitrospira lineage II, we identified ecophysiological traits that contribute to the ecological success of Nitrospira. Unexpectedly, N. moscoviensis possesses genes coding for a urease and cleaves urea to ammonia and CO2. Ureolysis was not observed yet in nitrite oxidizers and enables N. moscoviensis to supply ammonia oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers, suggests a wide distribution of this extended interaction between ammonia and nitrite oxidizers, which enables nitrite-oxidizing bacteria to indirectly use urea as a source of energy. A soluble formate dehydrogenase lends additional ecophysiological flexibility and allows N. moscoviensis to use formate, with or without concomitant nitrite oxidation, using oxygen, nitrate, or both compounds as terminal electron acceptors. Compared with Nitrospira defluvii from lineage I, N. moscoviensis shares the Nitrospira core metabolism but shows substantial genomic dissimilarity including genes for adaptations to elevated oxygen concentrations. Reciprocal feeding and metabolic versatility, including the participation in different nitrogen cycling processes, likely are key factors for the niche partitioning, the ubiquity, and the high diversity of Nitrospira in natural and engineered ecosystems.
['Koch|Hanna|H|', 'Lücker|Sebastian|S|', 'Albertsen|Mads|M|', 'Kitzinger|Katharina|K|', 'Herbold|Craig|C|', 'Spieck|Eva|E|', 'Nielsen|Per Halkjaer|PH|', 'Wagner|Michael|M|', 'Daims|Holger|H|']
D000641:Ammonia D001419:Bacteria D001426:Bacterial Proteins D017753:Ecosystem D005560:Formate Dehydrogenases D005561:Formates D005618:Fresh Water D016680:Genome, Bacterial D054892:Metagenome D008969:Molecular Sequence Data D009566:Nitrates D009573:Nitrites D058458:Nitrogen Cycle D010084:Oxidation-Reduction D010100:Oxygen D017422:Sequence Analysis, DNA D012722:Sewage D012988:Soil Microbiology D014508:Urea D014510:Urease
Nitrospira genome urease formate nitrification