SS2.04 Microbial Stoichiometry and Impacts on Biogeochemistry: From Genes to the Biosphere
Date: Friday, June 14, 2002
Time: 10:30:00 AM
Location: Carson C
 
HallEK, University of Minnesota, St. Paul, USA, hall0506@tc.umn.edu
Makino, W, , University of Minnesota, St. Paul, USA, makin005@tc.umn.edu
Cotner, J, B, University of Minnesota, St. Paul, USA, cotne002@umn.edu
 
EMPIRICAL ANALYSIS OF BACTERIAL GROWTH RATES, RNA/DNA LEVELS AND ORGANISMAL C:N:P STOICHIOMETRY
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Organismal C:N:P stoichiometry has been shown to correlate with specific growth rates. The underlying mechanism for this suggests that changes of growth rate are accompanied by changes in P-rich RNA which is the major contributor to the organismal phosphorus pool and thus alters organismal C:N:P stoichiometry. Although this trend is supported mainly by data from zooplankton cultures the mechanism of this hypothesis suggest it could apply to other organisms, such as aquatic bacteria. Laboratory experiments show support for this trend in mono-cultures of Escherichia coli. To test the robustness of this trend with field data we surveyed 126 lakes in the upper Midwest of the United States and sampled each system for bacterial production, bacterial RNA/DNA levels and less than one um particulate C:N:P levels. Lakes sampled ranged from ca 0.2 to 254 ug Chla/L (mean 13 ug/L) and total particulate phosphorus levels between ca 0.5 and 560 ug/L (mean 19 ug/L). We analyzed general trends found in the data set and possible mechanisms underlying those trends specific to the aquatic microbial community.