Soil microbial decomposers, including bacteria and fungi, are the gatekeepers of the soil carbon cycle, determining the fraction of decomposed carbon that becomes part of their biomass or is released into the atmosphere through respiration. In the context of climate change, understanding how rising temperatures will affect these microbial communities is crucial for predicting global carbon fluxes. Elevated temperatures could either increase or decrease the amount of carbon released into the atmosphere by soil microbes.
Numerous studies have shown that soil bacteria and fungi exposed to rising temperatures in situ exhibit shifts in their growth rate temperature dependencies, with both their minimum and optimal growth temperatures moving upward in response to the warming conditions. However, these adaptations are often measured at the community level, which limits our understanding of the ecological mechanisms involved. It remains unclear whether these changes are due to shifts in community composition toward warm-adapted taxa or physiological acclimation and evolution within existing taxa—possibly through mechanisms like horizontal gene transfer.
Objectives
This project aims to elucidate the mechanisms by which soil microbial communities adapt to increasing temperatures at the species level. By comparing the thermal traits of bacterial and fungal strains isolated from artificially warmed soils, we seek to determine whether thermal adaptation results from species sorting or physiological changes within species. Bacterial and fungal populations will be isolated from both control (ambient temperature) and warmed soils. These strains will be identified using DNA barcoding, and their thermal traits will be analyzed in relation to their phylogeny. The findings will be compared with previously acquired community-level thermal trait data to assess whether community-level thermal adaptation is primarily associated with microbial species sorting or physiological adaptation, and to determine if these processes differ between bacteria and fungi.
Methodolog
- Isolate bacteria and fungi from artificially warmed soils.
- Identify bacterial and fungal strains using DNA barcoding techniques.
- Measure growth rates of bacterial and fungal isolates at different temperatures.
- Model growth rates as a function of temperature to determine thermal traits.
Skills and techniques acquired
- Microbiology techniques for isolating and identifying microbes the molecular level.
- Methods for axenic bacterial and fungal cultivation and phenotyping.
- Analyzing thermal adaptation traits in relation to microbial phylogeny.
- Advanced data analysis and visualization skills.
Application process
- Flexible starting date,
- 45-60 cr
- Interested candidates should contact Dr. François Maillard at francois.maillard@biol.lu.se.