SS2.04 Microbial Stoichiometry and Impacts on Biogeochemistry: From Genes to the Biosphere
Date: Thursday, June 13, 2002
Location: Poster Session - VCC
 
MakinoW, University of Minnesota, St. Paul, USA, makin005@tc.umn.edu
Cotner, J, B, University of Minnesota, St. Paul, USA, cotne002@tc.umn.edu
Sterner, R, W, University of Minnesota, St. Paul, USA, stern007@tc.umn.edu
Elser, J, J, Arizona State University, Tempe, USA, j.elser@asu.edu
 
ARE BACTERIA MORE LIKE PLANTS OR ANIMALS? GROWTH RATE AND SUBSTRATAE DEPENDENCE OF BACTERIAL C:N:P STOICHIOMETRY
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Chemostat experiments with Escherichia coli at different medium C:P ratios revealed that E. coli RNA content and the contribution of RNA-P to the cellular P increased with increasing growth rate at all medium C:P levels. Although medium C:P was positively related to RNA content, growth rate had a much stronger effect than medium C:P, and increased RNA content due to increased growth resulted in low biomass C:P and N:P. Furthermore, the response of biomass C:P and N:P to the medium C:P and N:P revealed that E. coli is strongly homeostatic. This result and a literature survey suggest that each bacterial strain homeostatically regulates its elemental composition around characteristic biomass C:P and N:P values. Thus, shifts in the dominance of different strains in the environment are probably responsible for the large variation that has been observed in bacterial biomass C:P in nature, as suggested for crustacean zooplankton. These findings indicate that bacteria are more like animals than plants in terms of biomass C:P and N:P homeostasis.