%0 Journal Article
%T Affinity informs environmental cooperation between ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (Anammox) bacteria
%J -
%D 2019
%R https://doi.org/10.1038/s41396-019-0408-x
%X Anaerobic ammonia-oxidizing (Anammox) bacteria (AnAOB) rely on nitrite supplied by ammonia-oxidizing bacteria (AOB) and archaea (AOA). Affinities for ammonia and oxygen play a crucial role in AOA/AOB competition and their association with AnAOB. In this work we measured the affinity constants for ammonia and oxygen (half-saturation; km) of two freshwater AOA enrichments, an AOA soil isolate (N. viennensis), and a freshwater AnAOB enrichment. The AOA enrichments had similar kinetics (¦Ìmax ¡Ö 0.36 d£¿1, km,NH4 ¡Ö 0.78£¿¦ÌM, and km,O2 ¡Ö 2.9£¿¦ÌM), whereas N. viennensis had similar km values but lower ¦Ìmax (0.23 d£¿1). In agreement with the current paradigm, these AOA strains showed a higher affinity for ammonia (lower km,NH4; 0.34¨C1.27£¿¦ÌM) than published AOB measurements (>20£¿¦ÌM). The slower growing AnAOB (¦Ìmax ¡Ö 0.16 d£¿1) had much higher km values (km,NH4 ¡Ö 132£¿¦ÌM, km,NO2 ¡Ö 48£¿¦ÌM) and were inhibited by oxygen at low levels (half-oxygen inhibition; ki,O2 ¡Ö 0.092£¿¦ÌM). The higher affinity of AOA for ammonia relative to AnAOB, suggests AOA/AnAOB cooperation is only possible where AOA do not outcompete AnAOB for ammonia. Using a biofilm model, we show that environments of ammonia/oxygen counter diffusion, such as stratified lakes, favors this cooperation
%U https://www.nature.com/articles/s41396-019-0408-x