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Rapid nitrification involving comammox and canonical Nitrospira at extreme pH in saline-alkaline lakes |
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| Authors: | Anne Daebeler Queralt Güell-Bujons Maria Mooshammer Thomas Zechmeister Craig W Herbold Andreas Richter Michael Wagner Holger Daims |
| Institution: | 1. University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria;2. University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, Catalonia, Spain Contribution: Funding acquisition (supporting), Methodology (supporting), Writing - review & editing (supporting);3. Centre for Microbiology and Environmental Systems Science, Division of Terrestrial Ecosystem Research, University of Vienna, Vienna, Austria Contribution: Conceptualization (supporting), Data curation (equal), Formal analysis (equal), Methodology (equal), Writing - review & editing (supporting);4. Biological Station Lake Neusiedl, Illmitz, Austria Contribution: Data curation (supporting), Formal analysis (supporting), Methodology (supporting), Writing - review & editing (supporting);5. University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria Contribution: Data curation (supporting), Formal analysis (supporting), Methodology (supporting), Writing - review & editing (supporting);6. Centre for Microbiology and Environmental Systems Science, Division of Terrestrial Ecosystem Research, University of Vienna, Vienna, Austria Contribution: Resources (supporting), Supervision (supporting), Writing - review & editing (supporting);7. University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria The Comammox Research Platform, University of Vienna, Vienna, Austria Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark Contribution: Resources (supporting), Supervision (supporting);8. University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria The Comammox Research Platform, University of Vienna, Vienna, Austria Contribution: Conceptualization (equal), Funding acquisition (equal), Resources (equal), Supervision (supporting), Writing - review & editing (equal) |
| Abstract: | Nitrite-oxidizing bacteria (NOB) catalyse the second nitrification step and are the main biological source of nitrate. The most diverse and widespread NOB genus is Nitrospira, which also contains complete ammonia oxidizers (comammox) that oxidize ammonia to nitrate. To date, little is known about the occurrence and biology of comammox and canonical nitrite oxidizing Nitrospira in extremely alkaline environments. Here, we studied the seasonal distribution and diversity, and the effect of short-term pH changes on comammox and canonical Nitrospira in sediments of two saline, highly alkaline lakes. We identified diverse canonical and comammox Nitrospira clade A-like phylotypes as the only detectable NOB during more than a year, suggesting their major importance for nitrification in these habitats. Gross nitrification rates measured in microcosm incubations were highest at pH 10 and considerably faster than reported for other natural, aquatic environments. Nitrification could be attributed to canonical and comammox Nitrospira and to Nitrososphaerales ammonia-oxidizing archaea. Furthermore, our data suggested that comammox Nitrospira contributed to ammonia oxidation at an extremely alkaline pH of 11. These results identify saline, highly alkaline lake sediments as environments of uniquely strong nitrification with novel comammox Nitrospira as key microbial players. |
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