Ammonia-oxidizing archaea and their contribution to global nitrogen cycling: a review

Nitrification(oxidation of ammonia to nitrate via nitrite) plays a crucial role in the global nitrogen cycling. Along with the discovery of ammonia monooxygenase coding gene(amo A) sequences in archaea and the successful cultivation(isolation and enrichment) of ammonia-oxidizing archaea(AOA), it has been found that AOA was more abundant than AOB in most environments. And the contribution of AOA vs AOB to the nitrogen cycling is still under debate. In this mini-review, the ecological distribution, evolution, abundance and potential function involved the microbial nitrification were summarized based on the current knowledge. Furthermore, the perspective insights were discussed for the future research.