Two different hypotheses have been raised as to how temperature affects resource allocation in microorganisms. The translation-compensation hypothesis (TCH) predicts that the increase in enzymatic efficiency with temperature results in fewer required ribosomes per cell and lower RNA:protein ratio. In contrast, the growth rate hypothesis (GRH) predicts that increasing the growth rate with temperature requires more ribosomes and hence a higher cellular RNA:protein. We tested these two hypotheses in laboratory cultures of Prochlorococcus and Alteromonas as well as over an annual cycle in the Eastern Mediterranean Sea. The RNA:protein of Alteromonas mostly decreased with temperature in accordance with the TCH, while that of Prochlorococcus increased with temperature, as predicted by the GRH. No support was found for either hypothesis in surface waters from the Eastern Mediterranean, whereas the fraction of phosphorus in RNA was positively correlated with per-cell bacterial production in the deep chlorophyll maximum, supporting the GRH in this niche. A considerable part of the cellular phosphorus was not allocated to RNA, DNA, phospholipids or polyphosphate, raising the question which cellular molecules contain these P reserves. While macromolecular quotas differed significantly between laboratory cultures and field samples, these were connected through a power law, suggesting common rules of resource allocation.
Bibliographical noteFunding Information:
The authors thank the captains and crews of the R/V Mediterranean Explorer and R/V Bat Galim, as well as the SoMMoS sampling team, for help with the sample collection. The authors also thank the captain, crew and science team of cruise HKB‐SCS‐2021, and especially Jiying Li, for their help in obtaining samples and data from the South China Sea. The authors thank Dikla Aharonovich for assistance throughout the project and Tom Reich for the biofilm images. This study was supported by grant 1786/20 from the Israel Science Foundation (to Daniel Sher) and grant SMSEGL20SC02 from the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou, to Daniel Sher). Shira Givati was supported by PhD scholarships from the Yochai Bin Nun foundation (IOLR) and the University of Haifa.
© 2023 The Authors. Environmental Microbiology published by Applied Microbiology International and John Wiley & Sons Ltd.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics