Growing Thaumarchaeota from soil: isolating new strains of AOA and the search for a model system

Nitrification is a key process of the nitrogen cycle on earth. It contributes to the mineralization of organic nitrogen by allowing the transformation of ammonia into nitrites. Two groups of microorganisms are responsible for the rate-limiting first step of ammonia oxidation : ammonia-oxidizing bacteria and ammonia-oxidizing archaea (AOA), which all belong to the phylum Thaumarchaeota. Many studies have shown the presence of AOA in soil, but in spite of the availability of a few strains in pure culture, and the publication of several genomes, to date no organism can be considered as a model system. This talk will focus on the strategies used to isolate pure cultures of AOA from soils, some characteristics of the enrichments that we have been able to grow in the past year in the context of isolating ammonia oxidizers, and the perspectives that this kind of approach offers to researchers exploring the physiology of Thaumarchaeota and their role in soils.