Graeme W. Nicol

TL;DR: It is shown that archaeal ammonia oxidizers are more abundant in soils than their well-known bacterial counterparts, and crenarchaeota may be the most abundant ammonia-oxidizing organisms in soil ecosystems on Earth.

TL;DR: Findings suggest that different bacterial and archaeal ammonia oxidizer phylotypes are selected in soils of different pH and that these differences in community structure and abundances are reflected in different contributions to ammonia oxidation activity.

TL;DR: Investigation of niche specialisation in ammonia-oxidisers, and other microbial communities, requires characterisation of a wider range of environmentally representative cultures, emphasis on experimental studies rather than surveys, and greater consideration of small-scale soil heterogeneity.

TL;DR: Community structure changes were similar during incubation at different temperatures and much of the activity was due to a group of non-thermophile crenarchaea associated with subsurface and marine environments, rather than soil.

TL;DR: Current evidence for the relative importance of bacteria and archaea in the global nitrogen cycle is reviewed, based on metagenomic analysis and molecular techniques for estimation of gene and gene transcript abundance, changes in ammonia oxidizer community structure during active nitrification and phylogeny of natural communities.