Microorganisms support adaptation to climate change

Female polyps of the sea anemone Nematostella vectensis spawning here can directly inherit the temperature tolerance of the parent generation through the transmission of certain bacteria. Credit: HHU / Hanna Domin

Researchers at the University of Heinrich Heine Düsseldorf (HHU) and the University of Kiel (CAU), led by Professor Sebastian Fraune, are investigating the contribution of microbiomes to the thermal adaptation of living organisms using the example of the sea anemone Nematostella vectensis.As they discovered, this contribution is important and they report on it in the latest issue of the journal. Nature Communications..

all Multicellular organism An unimaginably large number of microorganisms have formed colonies and have co-evolved with them since the beginning of the evolutionary history of life.natural Microbial floraIn other words, the whole body and all of these bacteria, viruses, and fungi that live in the body are fundamentally important to the whole organism. For example, it performs important tasks for the host, such as helping to get nutrients and helping to defend. Pathogen.

HHU and CAU research teams have investigated how organisms support organisms in adapting to changing environmental conditions. In a study within the Collaborative Research Center (CRC) 1182, “Origin and Function of Metaorganisms,” they investigated the involvement of microbial flora in the thermal adaptation of sea anemones in so-called acclimation experiments.

Researchers led by Professor Sebastian Fraune of the HHU Zoological and Biological Interactions Institute, who is also the project leader of Kiel CRC1182, have been able to show that bacterial colony formation in animals changes as a result of adaptation. In addition, sea anemone organisms are more resistant to heat stress.In addition, the research team Causal relationship: The latter was also less sensitive to high temperatures when they transferred the heat-adapted microbial flora to non-adapted anemones. This is especially important for changing environmental conditions as a result of climate change.

Long-term acclimation experiment

The new study is based on a long-term study in which researchers have been studying the adaptation of sea anemones to changing environmental conditions for over four years. To do this, they treated clones of a single original animal and compared 50 genetically identical sea anemones in each of 15 different colonies. Researchers divided these colonies into three groups kept at 15, 20, and 25 degrees Celsius to analyze their adaptation to different temperatures.

During long observation periods, characteristic changes in the so-called phenotypes of sea anemones, namely changes in their appearance, including physiological characteristics, were revealed: above all, animals became significantly larger at low temperatures and altered reproduction. Mode.

The changes in temperature tolerance were also particularly interesting. “Sea anemones differ greatly in their tolerance to high temperatures. When exposed to very high temperatures of 40 degrees Celsius for 6 hours, animals adapted at 25 degrees Celsius survived almost exclusively,” the lead author said. Laura Baldassarre says. Of research.

Previous studies have suggested that adaptation to temperature stress may be associated with changes in animal microflora composition. Analysis of bacterial colonization of different colonies in adaptation experiments re-supported this hypothesis because the microbial flora of adapted animals also changed compared to non-adapted homologues.

“It seems quite reasonable that this adaptation, the so-called phenotypic plasticity, can be partially controlled by bacteria. Their much shorter production times are far more than possible via genetic recombination in the host organism. It enables fast adaptation, “says Fraune. The fact that there is a real causal link between changes in the microbial flora and temperature adaptation is currently being proven.

Microbiota transplantation provides confirmation

“In transplantation experiments, we transferred the microbial flora from anemones adapted to 15 degrees Celsius, 20 degrees Celsius, and 25 degrees Celsius to animals that were not adapted but were genetically identical. These animals also adopted high temperature tolerance. It turns out, “says Baldassarre.

Therefore, when the entire animal flora is transplanted, phenotypes with altered temperature tolerance can also be transplanted. Professor Fraune said, “We were able to establish a causal relationship between the composition of the microbial flora and environmental adaptation. Therefore, we experimentally define the concept of so-called hologenome, which defines evolution as the development of host organisms with colony-forming microorganisms. Confirm to. The entire meta-organism. “

Next, the research team analyzed whether the microbial flora altered by thermal acclimation is inherited between anemones, a prerequisite for a sustained adaptation process. In previous studies, scientists have already shown that in nematostella, certain bacteria can be passed on from the parent generation to the offspring. Therefore, the evolutionary benefits of heat adaptation can, in principle, be inherited directly and the associated bacteria do not necessarily have to be taken up from the environment. Current studies provide further evidence of transmission of maternal bacteria to offspring. Like parents, offspring have been shown to be more likely to survive temperature stress if the mothers adapt at 25 degrees Celsius.

Investigation of the mechanism at the species level

Their findings help researchers better understand the role of interactions between host organisms and microorganisms in rapidly changing adaptive processes. Environmental condition.. “Our results provide a new explanation for the mechanisms of rapid heat adaptation mediated by the microbial flora and how they are transmitted to the next generation,” Fraune said.

In further studies, Düsseldorf and Kiel scientists want to investigate the mechanism of adaptation in detail, with a particular focus on the role of the individual bacterial species involved. To this end, detailed bacterial genome analysis is in preparation for the planned third funding phase of CRC1182 by the German Research Foundation (Deutsche Forschungsgemeinschaft—DFG). They shed light on the possible individual relationships between the bacterium and specific metabolic processes of the host cell, and their effect on the temperature tolerance of the entire organism.

“Overall, it is important to have a better understanding of the bacterial composition of heat adaptation. It can play a fundamental role in many other organisms, from a variety of flora and fauna to the entire ecosystem such as coral reefs. Therefore, we need a deeper understanding of the underlying process, which is essential to better assess or, in some cases, mitigate the impact of global changes on species and habitats. ” Says.

How the environment and the microbiota jointly shape the body

For more information:
Plasticity mediated by Laura Baldassarre et al, Microbiota promotes thermal adaptation of the sea anemone Nematostella vectensis. Nature Communications (2022). DOI: 10.1038 / s41467-022-31350-z

Courtesy of Dusseldorf, Heinrich Heine University

Quote: Microorganisms support climate change adaptation (5 July 2022) 5 July 2022

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Microorganisms support adaptation to climate change

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