| Autor: |
Mueller AJ; University of Vienna, Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, Althanstrasse 14, 1090, Vienna, Austria., Jung MY; University of Vienna, Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, Althanstrasse 14, 1090, Vienna, Austria.; Department of Science Education, Jeju National University, 102 Jejudaehak-ro, Jeju, 63243, Republic of Korea., Strachan CR; Department for Farm Animals and Public Health, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria.; FFoQSI GmbH, Technopark 1C, 3430, Tulln, Austria., Herbold CW; University of Vienna, Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, Althanstrasse 14, 1090, Vienna, Austria., Kirkegaard RH; Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg, Denmark., Wagner M; University of Vienna, Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, Althanstrasse 14, 1090, Vienna, Austria.; Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg, Denmark.; University of Vienna, The Comammox Research Platform, Vienna, Austria., Daims H; University of Vienna, Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, Althanstrasse 14, 1090, Vienna, Austria. holger.daims@univie.ac.at.; University of Vienna, The Comammox Research Platform, Vienna, Austria. holger.daims@univie.ac.at. |
| Abstrakt: |
Chemolithoautotrophic nitrite-oxidizing bacteria (NOB) are key players in global nitrogen and carbon cycling. Members of the phylum Nitrospinae are the most abundant, known NOB in the oceans. To date, only two closely affiliated Nitrospinae species have been isolated, which are only distantly related to the environmentally abundant uncultured Nitrospinae clades. Here, we applied live cell sorting, activity screening, and subcultivation on marine nitrite-oxidizing enrichments to obtain novel marine Nitrospinae. Two binary cultures were obtained, each containing one Nitrospinae strain and one alphaproteobacterial heterotroph. The Nitrospinae strains represent two new genera, and one strain is more closely related to environmentally abundant Nitrospinae than previously cultured NOB. With an apparent half-saturation constant of 8.7 ± 2.5 µM, this strain has the highest affinity for nitrite among characterized marine NOB, while the other strain (16.2 ± 1.6 µM) and Nitrospina gracilis (20.1 ± 2.1 µM) displayed slightly lower nitrite affinities. The new strains and N. gracilis share core metabolic pathways for nitrite oxidation and CO 2 fixation but differ remarkably in their genomic repertoires of terminal oxidases, use of organic N sources, alternative energy metabolisms, osmotic stress and phage defense. The new strains, tentatively named "Candidatus Nitrohelix vancouverensis" and "Candidatus Nitronauta litoralis", shed light on the niche differentiation and potential ecological roles of Nitrospinae. |
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