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The Maximum Growth Temperature for Eukaryotes Is Thermodynamically Driven but Ecologically Contingent.
1School of Physics & Astronomy, Cardiff University, 4 The Parade, Cardiff CF24 3AA, UK.
Life (Basel, Switzerland)
|June 26, 2026
Summary
Eukaryotes have a lower maximum growth temperature than bacteria and archaea, limited by the thermodynamics of inherently disordered proteins (IDPs) and Earth's temperature. This explains the 65°C upper limit for eukaryotic life cycles.
Area of Science:
- Microbiology
- Biophysics
- Evolutionary Biology
Background:
- Life exists across a wide range of temperatures, with archaea and bacteria thriving above 100°C.
- Eukaryotes, however, have a significantly lower maximum growth temperature, typically not exceeding 65°C.
- The reasons for this divergence in thermal tolerance remain largely unexplained.
Purpose of the Study:
- To investigate the factors contributing to the lower maximum growth temperature observed in eukaryotes compared to other life domains.
- To explore the roles of chemical composition, genome structure, and protein characteristics in thermal adaptation.
- To determine the influence of inherently disordered proteins (IDPs) on eukaryotic thermal limits.
Main Methods:
- Comparative analysis of chemical and genomic features across different life domains.
- Statistical correlation analysis between IDP distribution and fungal growth temperatures (maximum, minimum, and range).
- Thermodynamic modeling of IDP behavior in eukaryotes under varying temperatures.
Main Results:
- Chemical and genome structural differences do not fully explain the eukaryotic thermal limit, except in Saccharomycotina fungi.
- The distribution of inherently disordered proteins (IDPs) strongly correlates with fungal maximum, minimum, and temperature range.
- A positive correlation exists between a species' temperature range and its maximum growth temperature.
Conclusions:
- The 65°C upper limit for eukaryotes is attributed to the thermodynamic properties of IDPs and current Earth temperature regimes.
- IDP thermodynamics inherently restrict the operational temperature range in eukaryotes.
- Ecological temperature fluctuations may further constrain eukaryotic thermal adaptation, necessitating experimental validation.
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