S. Leininger et al., "Archaea predominate among ammonia-oxidizing prokaryotes in soils," Nature, 442:806-9, 2006 (Cited in 84 papers)
To quantify the presence of ammonia-oxidizing archaea (AOA) in soil, Christa Schleper at the University of Bergen and colleagues sifted through 12 types of soil from three climate zones for amoA - a gene for a subunit of a key ammonia-oxidizing enzyme. PCR studies revealed that archaeal amoA is up to 3,000 times more abundant in soil than bacterial amoA, overturning a decades-old belief that bacteria are the largest contributors to soil nitrification.
Follow-up studies have detected AOA in ammonium-rich estuaries in Mexico, fertilized red soil in China, and sand from a Tennessee watershed. In July, researchers found that AOA are abundant even in sea floor sediments (Nature, 454:991-4, 2008).
However, "the real direct proof is still missing" - that soil archaea are actually fixing nitrogen, says Michael Wagner, a microbiologist at ...
