Scientists are now revisiting, and perhaps revising, their thinkingabout how Archaea, an ancient kingdom of single-celled microorganisms,are involved in maintaining the global balance of nitrogen and carbon.Researchers have discovered the first Archaea known to oxidize ammoniafor energy and metabolize carbon dioxide by successfully growing thetentatively named, Nitrosopumilus maritimus, in the lab.
"Data from several cultivation-independent, molecular experimentsled us to suspect that Archaea could be involved in the marine nitrogencycle. Subsequently having the organism isolated in the lab allowed usto confirm our suspicions," said David Stahl, professor of civil andenvironmental engineering at the University of Washington. Stahl's labgroup specializes in environmental microbiology and how microbialcommunities function in diverse locations including the oceans, hotsprings, animal intestines and the human mouth.
Archaea have primarily been associated with extremeenvironments like hot springs and deep-sea vents, but about a decadeago molecular studies proved their abundance in more common environsincluding the open ocean, freshwater and soil. Subsequent efforts togrow various samples of these organisms led to this cultivation of N.maritimus, or "dwarf belonging to the sea," by Stahl and scientists atthe Woods Hole Oceanographic Institution.
They report their work in the Sept. 22 issue of the journal Nature.
As the true range and relationship of Archaea to other microbesis revealed, information about N. maritimus will serve as benchmarksfor all microbiologists. Biochemical and genomic studies are alreadyunderway to learn the mechanisms by which N. maritimus uses nitrogenand how its physiology compares to other microorganisms.
The National Science Foundation's (NSF) Microbial Observatories(MO) program as well as an NSF postdoctoral fellowship in microbialbiology supported this work. In addition to molecular andgenome-enabled studies, the MO program funds new developments in thelaboratory cultivation of novel microorganisms--a worthy endeavorconsidering that less than 1 percent of Earth's microorganisms havebeen cultured in the lab.
Matt Kane, NSF program manager for this research said, "This isa great example of how new approaches to microbial cultivation andcutting-edge molecular techniques can complement one another to achievebig advances in our understanding of the complexity of our globalecosystem." Kane says studies like these continue to highlight theimportance of non disease-causing microorganisms and their criticalrole in our understanding of global environmental cycles.
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