Evolutionary Pathway Determines the Stoichiometric Response of Escherichia coli Adapted to High Temperature

Abstract

Microorganisms exhibit shifts in elemental stoichiometry in response to short-term temperature increases due to varying growth rate, biochemical reactions, and protein degradation. Yet, it is unknown how an organism's elemental stoichiometry will respond to temperature change on evolutionary timescales. Here we ask how cellular elemental stoichiometry and physiology change in Escherichia coli that have adapted to high temperature over 2,000 generations compared to their low temperature adapted ancestor. Cell lines evolved to a temperature of 42.2 • C via two, negatively epistatic adaptive pathways leading to mutations in either the RNA polymerase complex or the termination factor rho. Compared to the ancestor, high temperature adapted cell lines overall had 14% higher N:P ratios, but did not differ significantly in C:N or C:P. However, cell lines with mutations in the rho gene had 13% lower C:N and 34% higher N:P. Furthermore, the two adaptive strategies of the rho and RNA polymerase mutations varied significantly from one another, cell lines with the rho mutation had lower C:N, higher N:P and higher protein content compared to cell lines with the RNA polymerase mutation. Thus, specific adaptive pathways modulate the effect of temperature on the cellular elemental stoichiometry and may explain why the elemental composition of specific lineages is differentially affected by temperature changes.

Predators override rainfall effects on tropical food webs

“…Our lowest precipitation treatment had both variable and low water depths, and low wetness; therefore, the resultant frequent exposure to drought conditions may have triggered the production of nitrogen‐rich heat shock proteins in the mosquito larvae—even though survival was not affected. Heat shock proteins contribute to dehydration tolerance in Culex pipiens and other mosquito species (Benoit et al, 2010), and expression of heat shock proteins has been associated previously with greater tissue N content (Linzner et al, 2018). Alternatively, if drought induced faster development time of mosquito larvae, the greater demands on protein synthesis may have also increased body N content (Trakimas et al, 2019).…”

Increased biofilm formation due to high-temperature adaptation in marine Roseobacter

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