An Austrian study highlighted the behavior of soil bacteria during drought. “Simulating future climate conditions actually resulted in more bacteria remaining active despite drought,” the authors explain
by Matteo Cavallito
Some soil bacteria can be particularly resilient in times of drought, surviving and even thriving under these particular conditions. This was revealed in a study conducted by the Center for Microbiology and Environmental Systems Science (CeMESS) at the University of Vienna.
The research, published in the journal Nature Communications, brings new insights into an as-yet underexplored topic. “Until now, measuring the activity of microorganisms in dry soils and identifying which species remain active was challenging,” says a statement released by the Austrian university. “Thanks to a novel method developed by scientists at the University of Vienna, bacterial activity during drought periods can now be observed.”
A new method
In the study, some soil samples were incubated with isotopically labeled water vapor. The growing bacteria incorporated the oxygen from the vapor into their DNA, allowing growth to be measured without adding water to the soil. “Most bacteria became inactive as dryness increased. However, this wasn’t uniform across all microbial groups,” explained Dennis Metze, Ph.D. candidate and lead author of the study.
“In our experiments, drought caused >90% of bacterial and archaeal taxa to stop dividing and reduced the growth rates of persisting ones,” the study states.
Specifically, “Under drought, growing taxa accounted for only 4% of the total community as compared to 35% in the controls.” Furthermore, bacterial growth during drought was affected by whether the soils had been exposed to current or future climatic conditions, which means higher temperatures and CO2 concentrations.
Bacteria will become more drought tolerant
In the course of the research, the University of Vienna note explains, the authors observed 54 experimental plots in which future weather and climate conditions were simulated. Using infrared heaters and adjusting CO2 concentrations, in other words, the researchers were able to shape reliable scenarios by analyzing the behavior of microorganisms.
“Simulating future climate conditions actually resulted in more bacteria remaining active despite drought,” explains Andreas Richter, professor of ecosystem research and head of CeMESS.
In particular, the research says, “Six years of pre-exposure to future climate conditions (3 °C warming and + 300 ppm atmospheric CO2) alleviated drought effects on microbial growth, through more drought-tolerant taxa across major phyla, accounting for 9% of the total community.”
New insights for the future
Research has shown that under the simulated conditions of climate change, more drought-tolerant species were able to establish themselves in the soil. Among them, a bacterium of the genus streptomycete, which is particularly resistant to drought, has spread in dry soils and accounts for a significant share of total bacterial activity. A phenomenon that has major implications for the soil ecosystem.
“Previous studies have indicated that such bacteria mi ght play a role in aiding plants to cope with drought,” observes the statement. The study, in short, provides important information about the adaptive capacity of microorganisms to deal with climate change and also about their ability to promote plant health and growth and to regulate carbon sequestration.