"Carbon limited means that these organisms have less to eat. You need carbon for making biomass," Klotz added. "A good portion of these guys are fermenters and they produce products that serve others as reductant and energy sources hydrogen, formate, acetate. If that is not happening because the carbon is low, then only the fast and cheap will prevail, which perform predominantly denitrification."
Though the findings are fundamental, Strous and Klotz both stress that gaining a more conclusive understanding of dynamics of the microbial systems in the environment that process the new, human-caused abundance of fixed nitrogen has important implications.
"When you look at the coastal systems we studied," Strous said, "those are actually fairly important in terms of getting rid of the nutrients in Europe.
"We understand this better now and this understanding is not trivial because the outcome of this competition is really important in determining primary productivity -- because ammonium from ammonification is directly re-usable by the primary producers and with denitrification the nitrogen is mainly lost. So this hard-to-study bacterial competition is really important in determining that primary productivity. In any modeling you do on how human impact causes global change, this is a very important piece of the puzzle."
Klotz stresses how the study shows the importance of having new "omics" tools metagenomics, transcriptomics, proteomics, etc. to help study in real time the metabolic activity and changes going on in complex bacterial communities.
"We looked for what genes were being expressed, what proteins were there and we could correlate and assign inventory to lifestyles of organisms. We had taxonomic markers because we could assign N-cycle relevant genes to known genomes, so we knew who we could attrib
|Contact: James Hathaway|
University of North Carolina at Charlotte