"We measured the abundance of the particular crenarchaeota gene alongside the same type of gene from bacteria," explains Schleper.
The tally suggested that copies of the archaeal gene in the soil samples were up to 3,000 times more abundant than copies of the bacterial gene. High amounts of lipids specific to crenarchaeota confirmed the organism's presence.
At Penn State, Schuster used a novel technique to directly sequence only the transcribed portion of the genomes from soil organisms, thus giving proof that crenarchaeota are in fact active and not just dormant residents in the soil.
Crenarchaeotal gene counts also do not change with soil depth, while bacterial gene counts drop significantly as one goes deeper.
"It might mean that they can oxidize ammonia at least with less oxygen and probably also with less ammonia, but we don't know for sure. Our data clearly say, that the archaea are more versatile in their life style than bacteria," says Schuster, also a researcher at Penn State's Centers for Infectious Disease Dynamics and Comparative Genomics and Bioinformatics.
Despite their abundance, it is not yet clear if crenarchaeota oxidize more ammonia than regular bacteria, and what that might mean for the ecological impact of ammonia oxidation, or the nitrogen cycle. We will have to study the nitrification activity of archaea and their underlying biochemistry, says Schleper, who initiated the study.
"Perhaps the measured amounts of greenhouse gases such as nitric oxide and nitrous oxide are not produced by bacteria, but by a very different group of organisms, namely archaea," said Schleper. "But it is not c