Are bacteria more like plants or animals? Growth rate and resource dependence of bacterial C : N : P stoichiometry

Authors

  • W. Makino,

    Corresponding author
    1. Department of Ecology, Evolution & Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, MN 55108, and
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    • Present address: Center for Ecological Research, Kyoto University, 509-3 Kamitanakami Hirano, Otsu, Shiga 520-2113, Japan.

  • J. B. Cotner,

    1. Department of Ecology, Evolution & Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, MN 55108, and
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  • R. W. Sterner,

    1. Department of Ecology, Evolution & Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, MN 55108, and
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  • J. J. Elser

    1. Department of Biology, Arizona State University, Tempe, AZ 85287, USA
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†Author to whom correspondence should be addressed. E-mail: wm@ecology.kyoto-u.ac.jp

Summary

  • 1We examined the relative importance of resource composition (carbon : phosphorus molar ratios which varied between 9 and 933) and growth rate (0·5–1·5 h−1) to biomass carbon : nitrogen : phosphorus stoichiometry and nucleic acid content in Escherichia coli grown in chemostats, and in other heterotrophic prokaryotes using published literature.
  • 2Escherichia coli RNA content and the contribution of RNA-P to total cellular P increased with increasing growth rate at all supply C : P ratios. Growth rate had a much stronger effect on biomass C : P than did supply C : P, and increased RNA content resulted in low biomass C : P and N : P ratios.
  • 3However, we observed only twofold variations in biomass C : P and N : P ratios in the experiments, despite a difference of two orders of magnitude in C : P and N : P supply. The response of biomass C : P and N : P ratios to alteration of the supply C : P and N : P ratios revealed that E. coli was strongly homeostatic in its elemental composition.
  • 4This result, and a literature survey, suggest that each heterotrophic bacterial strain regulates its elemental composition homeostatically within a relatively narrow range of characteristic biomass C : P and N : P ratios.
  • 5Thus shifts in the dominance of different bacterial strains in the environment are probably responsible for the large variation in bacterial biomass C : P, as has been 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.

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