Soil bacteria evolve with climate change

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Evolution is usually thought to occur over millions of years, but researchers at the University of California, Irvine, have discovered that bacteria can evolve in 18 months in response to climate change. ..In a study published in Minutes of the National Academy of Sciences, UCI biologists have discovered that evolution is one way soil microbes deal with global warming.

The soil microbial flora (a collection of bacteria and other microorganisms in the soil) is an important engine of the global carbon cycle. Microorganisms break down dead plant materials, recycle nutrients into ecosystems, and release carbon into the atmosphere. Multiple environmental factors affect the composition and function of soil microbial flora, but these responses are usually studied from an ecological point of view, and which microbial species increase or decrease abundance in response to changing environmental conditions. Ask if you want to. In the current study, the UCI team investigated whether bacterial species in soil also evolve when the environment changes.

“We know that bacterial evolution can occur very quickly, like responding to antibiotics, but we don’t know how important evolution is to bacteria in an environment with ongoing climate change.” , Former graduate student at the University of California, Irvine.

Due to some unique properties, soil microbes should be able to adapt quickly to new climatic conditions. Due to the abundance of microorganisms and the ability to reproduce in just a few hours, rare genetic mutations that allow adaptation to new climatic conditions can occur by chance in a short period of time. However, much of what is known about bacterial evolution comes from controlled laboratory experiments in which bacteria grow in flasks with artificial foods. It was unclear whether evolution occurred fast enough in soil and was related to the effects of the current rate of climate change.

“Current predictions about how climate change affects microbial flora assumes that microbial species are static, so whether bacteria can evolve rapidly in natural environments such as soil. I wanted to test it, “Dr. Chase explained.

To measure evolution in the natural environment, researchers have conducted the first bacterial evolution experiment in the field using a soil bacterium called Curtobacterium. Researchers used 125 “microbial cages” filled with microbial foods made of dead plant material. (The cage allows the transport of water, but not other microbes.) The cage then exposed the bacteria to a variety of climatic conditions throughout Southern California’s elevation gradient. The team conducted two parallel experiments over 18 months to measure both the ecological and evolutionary responses of bacteria.

“The microbial cage allowed us to be exposed to different environmental conditions in different places while controlling the types of bacteria present. For example, the warm and dry conditions of desert places, which contribute to the genetic diversity of I was able to test how it affects a single Curtobacterium species. “

Eighteen months later, scientists sequenced bacterial DNA from the experimental microbial cage. In the first experiments involving diverse soil microbial flora, various Curtobacterium species were abundantly altered and were the expected ecological response. A second experiment in the same time frame altered the genetic diversity of a single Curtobacterium bacterium, revealing an evolutionary response to the same environmental conditions. The authors conclude that both ecological and evolutionary processes can contribute to how soil microbial flora responds to changes in climatic conditions.

“This study shows that we can observe the rapid evolution of soil microorganisms. This is an exciting achievement. The next goal is the importance of evolutionary adaptation to soil ecosystems under future climate change. It’s about understanding, “says co-author Jennifer Martinie. Ecology and evolutionary biology co-supervising the UCI Microbial Initiative.

Studies have shown that microbial-plant interactions influence the microbial response to climate change.

For more information:
Alexander B. Chase et al., Adaptive differentiation and rapid evolution of soil bacteria along climatic gradients, Minutes of the National Academy of Sciences (2021). DOI: 10.1073 / pnas.2101254118

Courtesy of the University of California, Irvine

Quote: Soil bacteria evolve with climate change (April 28, 2021) April 28, 2021

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Soil bacteria evolve with climate change

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