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A single Thaumarchaeon drives nitrification in deep oligotrophic Lake Constance
Author(s) -
Herber Janina,
Klotz Franziska,
Frommeyer Benjamin,
Weis Severin,
Straile Dietmar,
Kolar Allison,
Sikorski Johannes,
Egert Markus,
Dannenmann Michael,
Pester Michael
Publication year - 2020
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.14840
Subject(s) - thaumarchaeota , ammonia monooxygenase , nitrification , hypolimnion , nitrospira , biology , nitrogen cycle , environmental chemistry , bacterioplankton , ecology , anoxic waters , nitrosomonas , ammonium , operational taxonomic unit , archaea , nitrate , 16s ribosomal rna , eutrophication , bacteria , nitrite , chemistry , nutrient , nitrogen , genetics , organic chemistry , phytoplankton
Summary Ammonia released during organic matter mineralization is converted during nitrification to nitrate. We followed spatiotemporal dynamics of the nitrifying microbial community in deep oligotrophic Lake Constance. Depth‐dependent decrease of total ammonium (0.01–0.84 μM) indicated the hypolimnion as the major place of nitrification with 15 N‐isotope dilution measurements indicating a threefold daily turnover of hypolimnetic total ammonium. This was mirrored by a strong increase of ammonia‐oxidizing Thaumarchaeota towards the hypolimnion (13%–21% of bacterioplankton) throughout spring to autumn as revealed by amplicon sequencing and quantitative polymerase chain reaction. Ammonia‐oxidizing bacteria were typically two orders of magnitude less abundant and completely ammonia‐oxidizing (comammox) bacteria were not detected. Both, 16S rRNA gene and amoA (encoding ammonia monooxygenase subunit B) analyses identified only one major species‐level operational taxonomic unit (OTU) of Thaumarchaeota (99% of all ammonia oxidizers in the hypolimnion), which was affiliated to Nitrosopumilus spp. The relative abundance distribution of the single Thaumarchaeon strongly correlated to an equally abundant Chloroflexi clade CL500‐11 OTU and a Nitrospira OTU that was one order of magnitude less abundant. The latter dominated among recognized nitrite oxidizers. This extremely low diversity of nitrifiers shows how vulnerable the ecosystem process of nitrification may be in Lake Constance as Central Europe's third largest lake.