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Relativity Trumps Absolutism: P pools in microbes and their effects on stoichiometry

Dr. James Cotner, University of Minnesota

Abstract

A key component of the Growth Rate Hypothesis is that the elemental composition of cells is coupled to the rate at which biomass is turning over. One of the central elements to this hypothesis is phosphorus (P), which is primarily found in cells as nucleic acids (RNA and DNA) which are P-rich. Therefore, faster growing organisms should have more P in their biomass than slower growing ones, right? Well, not so fast, because biomass stoichiometry is really all about the relative contributions of different biomass components. Although organisms grow faster at higher temperatures, their relative growth rate may not increase or could actually decrease as the temperature rises and this means that the proportion of biomass focused on growth (i.e., nucleic acids) may decrease as well. Our recent work has demonstrated that there can be clear effects of relative growth rates on the biomass composition of heterotrophic bacteria but those effects differ to a great extent depending on the availability of limiting and non-limiting nutrients, which specific nutrient is limiting, and the relative growth rate. We will explore the implications of relative growth rate for stoichiometric homeostasis and internal pools of phosphorus in prokaryotes. 

Part of the 2016 Earth Planetary and Space Sciences Institute (EPSSI) Seminar Series

Annual seminar series on topics related to Earth Planetary and Space Sciences and course UN 4000 REMOTE SENSING.