Inactive bacteria naturally present in soil contribute to the persistence of essential microbial functions after a fire.
Sciences et technologies

Inactive bacteria naturally present in soil contribute to the persistence of essential microbial functions after a fire.

A new study by researchers from CNRS and Michigan State University has shed light on the remarkable mechanisms of resilience and recovery of soil microbiomes after an underground coal seam fire. Published in a scientific journal Environmental lettersThe results obtained provide original information about the dynamics of bacterial communities in soils affected by fires.

The study used long-term monitoring of the soil microbiome to analyze the effects of a thermal disturbance caused by a fire in the Centralia coal seam (Pennsylvania, USA). The researchers observed a gradual decline in disturbance intensity over the years, accompanied by changes in environmental conditions such as cooling of fire-damaged areas.

Visualization of a coal seam
Figure 1: Ground above an active fire burning below in the coal seam at the Centralia site (Pennsylvania, USA). There are no factories above the hottest active areas, and coal slag is visible in the foreground. © Samuel E. Barnett

One of the key findings of the study is the apparent resilience of bacterial communities despite the environmental challenges caused by coal seam fires. Through comprehensive analyzes of microbial diversity based on high-throughput sequencing of purified soil DNA, the scientists demonstrated that these communities have a high capacity for resilience even after such unusual and intense exposure.

visual temperature of the coal seam
Figure 2: Temperature sensor inserted into a crack in the active degassing area. This is an area above an active fire that has broken through the surface of the ground from below. © Samuel E. Barnett

Dr Shade said: “Our research highlights the resilience of soil microbiomes to long-term stressors, which is critical to understand given the climate crisis. Many people don’t realize that “an incredible number of soil microbes are simply dormant. This is an important point because active microbes are those that contribute to ecosystem functions. Our research aims to understand how different types of microbes function: “are activated or inactivated during destruction and what these dynamics mean for the overall recovery process.”

Thus, dormant microorganisms contributed to the restoration of bacterial diversity in fire-damaged soils during the initial recovery phase and were subsequently able to reactivate to restore their functions.

The study represents an important contribution to the field of microbial ecology and environmental sciences as it provides a better understanding of the resilience of soil microbiomes in the face of large-scale disturbances. The research team hopes these findings will encourage the broader development of effective microbiome restoration strategies in ecosystems affected by climate change and other human activities.

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