Archives par mot-clé : Micro-organisms

Microbes that co-operate contribute more carbon emissions

by Imperial College London, Feb 13, 2023 in ScienceDaily

Despite being small, microbes, and especially bacteria, contribute a lot to the global carbon cycle — the movement of carbon in various forms through nature. Its level in the atmosphere, and so its influence on climate change, is controlled by a series of sources and sinks, such as respiration and photosynthesis respectively.

Now, new research from Imperial College London and University of Exeter scientists has shown that, when warmed, bacterial communities that have matured to co-operate release more carbon dioxide (CO2) than communities that are in competition with each other.

The results are published in Nature Microbiology.

Co-author Dr Tom Clegg, who led the theory development from the Department of Life Sciences (Silwood Park) at Imperial, said: “Our findings have far-reaching implications given the significant contributions that bacterial communities make to the carbon cycle. We show that changes in bacterial species interactions can rapidly and substantially increase the carbon emissions from natural ecosystems worldwide.”

Bacteria — like humans — respire, taking in oxygen and releasing CO2. Of the many factors that control their level of respiration, temperature is particularly important.

Bacteria form communities of different species in all habitable environments, including in soil, puddles, and in our guts. When communities first form, the bacterial species are often ‘competitive’, each trying to get the best resources.

Breakthrough gives insight into early complex life on Earth

by H. Devlin, January 15, 2020 in TheGuardian

For the first 2 billion years, life on Earth comprised two microbial kingdoms – bacteria and archaea. They featured an innumerable and diverse variety of species, but, ultimately, life on Earth was not that exciting judged by today’s standards.

Then, the theory goes, a rogue archaeon gobbled up a bacterium to create an entirely new type of cell that would go on to form the basis of all complex life on Earth, from plants to humans.

Now, for the first time, scientists have succeeded in culturing an elusive species of archaea believed to be similar to the ancestor that gave rise to the first sophisticated cells, known as eukaryotes. The work has been described as a “monumental” advance that sheds new light on this evolutionary milestone.

Nick Lane, professor of evolutionary biochemistry at UCL, described the work as “magnificent”, while a commentary by two other experts in the field said it marked a “huge breakthrough for microbiology”.

Like bacteria, archaea continue to thrive on Earth today. But despite the pivotal role they are thought to have played in the emergence of complex life there has been relatively little research on them. Many species are found in inhospitable environments and are incredibly difficult to grow in the lab.

The Japanese team behind the latest advance has dedicated 12 years to the effort, overcoming a series of setbacks along the way.

The archaeon which was cultured and characterised from deep marine sediment. Photograph: Nature


Global-scale evaluation of role of soil minerals in carbon storage

by U. of California – Santa Barbara, January 2, 2019 in ScienceDaily

“We’ve known for quite a long time that the carbon stored on minerals is the carbon that sticks around for a long time,” said Chadwick, co-author of the paper, “Climate-driven thresholds in reactive mineral retention of soil carbon at the global scale,” published in the journal Nature Climate Change. How much carbon the soil can take and how much it can keep, he said, are dependent on factors including temperature and moisture.

“When plants photosynthesize, they draw carbon out of the atmosphere, then they die and their organic matter is incorporated in the soil,” Chadwick explained. “Bacteria decompose that organic matter, releasing carbon that can either go right back into the atmosphere as carbon dioxide or it can get held on the surface of soil minerals.”


Carottes de glace, CO2 et micro-organismes

by Paul Berth, 22 novembre 2018, in ScienceClimatEnergie

Les microbulles de gaz emprisonnées dans les carottes de glace sont fréquemment utilisées pour estimer le taux de CO2 de l’atmosphère du passé. Il s’agit de méthodes de mesure indirectes. Par exemple la carotte de glace EPICA Dome C en Antarctique nous suggère que le CO2 de l’atmosphère a varié entre 180 et 300 ppmv pendant les derniers 650 000 ans (Brook 2005). Cependant, le taux de CO2 observé dans ces carottes de glace représente-il vraiment l’atmosphère du passé? Nous allons montrer ici qu’un paramètre est souvent négligé par les glaciologues, et que ce paramètre pourrait avoir un effet considérable sur le résultat des analyses : il s’agit de la présence de micro-organismes dans la glace et les microbulles.