Copper limiting threshold in the terrestrial ammonia oxidizing archaeon Nitrososphaera viennensis

Carolina Reyes, Logan Hodgskiss, Oliver Baars, Melina Kerou, Barbara Bayer, Christa Schleper, Stephan Krämer

Ammonia oxidizing archaea (AOA) inhabiting soils have a central role in the global nitrogen cycle. Copper (Cu) is central to many enzymes in AOA including ammonia monooxygenase (AMO), the enzyme involved in the first step of ammonia oxidation. This study explored the physiological response of the AOA soil isolate, Nitrososphaera viennensis (EN76T) to Cu-limiting conditions in order to approach its limiting threshold under laboratory conditions. The chelator TETA (1,4,8,11-tetraazacyclotetradecane N, N’, N’’, N’’’-tetraaceticacid hydrochloride hydrate) with selective affinity for Cu2+ was used to lower bioavailable Cu2+ in culture experiments as predicted by thermodynamic speciation calculations. Results show that N. viennensis is Cu-limited at concentrations ≤10-15 mol L-1 free Cu2+ compared to standard conditions (10-12 mol L-1). This Cu2+ limiting threshold is similar to pure cultures of denitrifying bacteria and other AOA and AOB inhabiting soils, freshwaters and sewage (<10-16 mol L-1), and lower than pure cultures of the marine AOA Nitrosopumilus maritimus (<10-12.7 mol L-1), which also possesses a high amount of Cu-dependent enzymes.

Department of Environmental Geosciences, Department of Ecogenomics and Systems Biology
External organisation(s)
North Carolina State University
Research in Microbiology
Publication date
Peer reviewed
Austrian Fields of Science 2012
Microbiology, Environmental geosciences
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