Low-Temperature Limits of Microbial Growth and Metabolism

TL;DRAbstract

Depending on wind speed and direction, microbes are swept up from diverse terrestrial and oceanic environments and blown onto glacial ice. The activation energy for survival metabolism turns out to be ~110 kJ, but with an ~106-fold smaller preexponential factor than for unlimited growth. The arrival rates of bacteria and nonmicrobial dust blown from African desert sources to an air collector on Barbados showed similar patterns of seasonal and daily. In seeking to interpret the rapid decrease in fluorescence intensities of tryptophan (Trp) in the top 120 m of ice and the flattening of intensity values at greater depth, researchers carried out ground-truth measurements of cell concentrations in ice from several sites in Antarctica and Greenland. The main conclusion is that the depth dependence of cell concentration seen with epifluorescence microscopy is far weaker than the ~20-fold decrease with depth of the chlorophyll (Chl) and Trp fluorescence shown. The weak decrease in microbial co

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