Soil microbes are tiny organisms that live in the soil and perform various functions that affect the global carbon cycle. They decompose plant material, recycle nutrients, and store carbon in the soil. However, most of them are unknown and poorly represented in climate models. A new study by scientists from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Lawrence Livermore National Lab has revealed how soil microbes can evolve and adapt to changing climate conditions, and how this can improve the accuracy of climate predictions.

Microbial Evolution in the Field

The researchers conducted a novel experiment to measure the evolution of a soil bacterium called Curtobacterium in response to different climate scenarios. They used 125 “microbial cages” filled with microbial food made of dead plant material and exposed them to a range of climate conditions across an elevation gradient in Southern California. They collected samples from the cages after 18 months and sequenced the genomes of the bacteria to detect any genetic changes.

They found that the bacteria had evolved in response to climate conditions such as temperature, moisture, and plant diversity. For example, the bacteria at higher elevations had more genes related to cold tolerance and nutrient acquisition, while the bacteria at lower elevations had more genes related to heat tolerance and stress response. The researchers also found that the evolution of the bacteria affected their ability to store carbon in the soil, which has implications for the global carbon cycle and climate change.

Microbial Genomes for Better Models

The study demonstrates the importance of incorporating microbial genetic information into climate models, which are essential tools for predicting and addressing climate change. Current models often fail to account for the diversity and dynamics of soil microbes, which are a critical player in ecosystem soil carbon sequestration. By using the DNA from soil microbes, the researchers were able to create better models that can capture how different plant types, crops, or cultivars can collaborate with soil microbes to enhance carbon storage and soil health.

“Our research shows the advantage of assembling the genetic information of microorganisms directly from soil. Previously, we only had information about a small number of microbes studied in the lab,” said Berkeley Lab Postdoctoral Researcher Gianna Marschmann, the paper’s lead author. “Having genome information allows us to create better models capable of predicting how various plant types, crops, or even specific cultivars can collaborate with soil microbes to better capture carbon. Simultaneously, this collaboration can enhance soil health.”

The research is part of the “Microbes Persist” Soil Microbiome Scientific Focus Area project, which is funded by the DOE Office of Science. The project aims to understand how soil microbes persist and function in changing environments and how they affect the global carbon cycle. The project involves scientists from Berkeley Lab, Lawrence Livermore National Lab, Pacific Northwest National Laboratory, Oak Ridge National Laboratory, and several universities.

The paper, titled “Soil microbial evolution shapes ecosystem responses to climate change,” was published in the journal Nature Microbiology. The corresponding authors are Eoin Brodie of Berkeley Lab and Jennifer Pett-Ridge of Lawrence Livermore National Lab.