Dormant strains of bacteria that previously adapted to cope with certain temperatures are being reactivated during climate change, according to a report published today in Elif.
The results have important implications for predicting the impact of global warming on ecosystems.
Microbes are integral to ecosystem function due to their key roles as pathogens, food sources and in nutrient recycling. To understand the profound impact of climate change on the function of different ecosystems, it is therefore necessary to study the microbial communities within them.
“Microbial communities can respond to warming in the short term by acclimation — developing unique traits to match their environment — or in the long term by adaptation, where they make evolutionary changes over many generations,” explains lead author Thomas Smith , Research Associate. at the Georgina Mace Center for the Living Planet, Imperial College London, UK. “But there is a third mechanism, called species sorting, by which the composition of the entire community—that is, the species present—changes with changes in temperature. The importance of species sorting in relation to acclimation and adaptation has not previously been explored in the context of microbial community responses to temperature change.”
To address this, the team conducted a species-sorting experiment, where they grew replicate communities of soil bacteria collected from a single site at different temperatures ranging from 4°C to 50°C. They then measured the growth and metabolism of each isolated strain of bacteria at these different temperatures to determine their thermal performance, and studied the genetic sequences of the isolated bacteria to see how the temperature response traits evolved over time.
They found that evolutionarily and functionally distinct communities emerged at each of the temperature conditions, driven by the resuscitation of microbial strains that had been inactive under the previous environmental conditions. This suggests that—rather than new bacteria moving into a community to suit new conditions—the parent community hosts multiple bacterial strains that are pre-adapted to survive at different temperatures and can switch on when their temperature favorite is reached. As a result, microbial communities in nature are likely able to respond rapidly to temperature fluctuations.
“Understanding the relative importance of acclimation, adaptation and species sorting in the assembly and turnover of microbial communities is key to determining how quickly they can respond to temperature changes. To date, a mechanistic basis for these community-level responses has not been discerned,” concludes lead author Thomas Bell, Professor of Microbial Ecology at the Georgina Mace Center for the Living Planet, Imperial College London. “We found that resuscitating functional diversity within a microbial community can allow the entire community to survive in response to temperature changes. Further studies of other microbial communities – such as those that live in water – will support more accurate predictions of the effects of climate change on different ecosystems.”
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Materials provided by Elif. Note: Content may be edited for style and length.