Archives par mot-clé : Microbes

Ancient plankton-like microfossils span two continents

by Penn State, July 13, 2017 in ScienceDaily

Large, robust, lens-shaped microfossils from the approximately 3.4 billion-year-old Kromberg Formation of the Kaapvaal Craton in eastern South Africa are not only among the oldest elaborate microorganisms known, but are also related to other intricate microfossils of the same age found in the Pilbara Craton of Australia, according to an international team of scientists.

Contamination of the Arctic reflected in microbial metagenomes from the Greenland ice sheet

by A.L. Hauptmann et al., July 11, 2017

Globally emitted contaminants accumulate in the Arctic and are stored in the frozen environments of the cryosphere. The microbial potential to degrade anthropogenic contaminants, such as toxic and persistent polychlorinated biphenyls, was found to be spatially variable and not limited to regions close to human activities.

Fungi are key players of the deep biosphere

by Linnaeus University, July 4, 2017

In addition to the life on the surface of the Earth and in its oceans, ecosystems have evolved deep under us in a realm coined the “deep biosphere” which stretches several kilometers down into the bedrock. Down there, the conditions are harsh and life is forced to adjust to a lifestyle that we at the surface would call extreme. One major difference to surface conditions is the lack of oxygen; a compound we take for granted and consider to be a prerequisite for survival but which subsurface life has to cope without.

Original article here (Nature Communication)

Bacteria Are Eating Most Of The 2010 BP Oil Spill

by Andrew Follett, June 28 in ClimateChangeDipatch

The study found that dispersants broke up the oil into tiny droplets, making them less buoyant and unable to float to the surface. This meant that the oil formed a layer deep below the surface of the water, making it easier for microbes that live in the deep ocean to eat it. However, scientists weren’t able to measure the exact amount of oil eliminated by the microbes.

Due largely to these oil-eating bacteria, the Gulf of Mexico recovered from the Deepwater Horizon oil spill faster than scientists thought possible and has returned to pre-spill levels of environmental health.

Methane-munching microbes living in the deep biosphere for 400 million years: An analogue for extra-terrestrial life

by Linnaeus University, May 9, 2017 in ScienceDaily

It is becoming more and more appreciated that a major part of the biologic activity is not going on at the ground surface, but is hidden underneath the soil down to depths of several kilometres in an environment coined the « deep biosphere ». Studies of life-forms in this energy-poor system have implications for the origin of life on our planet and for how life may have evolved on other planets, where hostile conditions may have inhibited colonization of the surface environment. The knowledge about ancient life in this environment deep under our feet is extremely scarce.

Oldest evidence of life on land found in 3.48 billion-year-old Australian rocks

by UNSW Sydney, May 9, 2017 in ScienceDaily

Fossils discovered by UNSW scientists in 3.48 billion year old hot spring deposits in the Pilbara region of Western Australia have pushed back by 580 million years the earliest known existence of microbial life on land.

he Pilbara deposits are the same age as much of the crust of Mars, which makes hot spring deposits on the red planet an exciting target for our quest to find fossilised life there.”

Mining: Bacteria with Midas touch for efficient gold processing

by University of Adelaide, April 28, 2017, in Science News

Special ‘nugget-producing’ bacteria may hold the key to more efficient processing of gold ore, mine tailings and recycled electronics, as well as aid in exploration for new deposits, University of Adelaide research has shown.

Now they have shown for the first time, just how long this biogeochemical cycle takes and they hope to make to it even faster in the future.

Les biominéraux microbiens : des gisements terrestres à l’exobiologie

D. Gillan (U. Mons) et A. Préat (ULB)

En raison de la toxicité des métaux lorsque ceux-ci sont en trop grande concentration dans l’environnement, le monde cellulaire a développé toute une série de mécanismes de résistance qui commencent à être bien connus chez les bactéries. Certains de ces mécanismes produisent des minéraux pouvant alors être qualifiés de biominéraux. De nombreux biominéraux ont ainsi été identifiés dans le monde bactérien. Cela va de la calcite aux oxydes de fer et de manganèse en passant par le phosphate de plomb et d’uranium. L’intérêt de bien connaître les processus de biominéralisation microbienne réside dans le fait qu’ils peuvent servir de biosignature. En effet, lesbiominéraux peuvent être préservés au cours des temps géologiques alors que les cellules à basede carbone se décomposent beaucoup plus rapidement.

La bonne connaissance de la structure de ces biominéraux nous offre un outil précieux qui pourrait être utilisé dans le cadre de la recherche de la vie sur d’autres planètes. Sur terre, l’activité des microorganismes a conduit depuis 3,7 milliards d’années à la formation de gisements minéraux encore exploités. De nombreux exemples sont connus comme les fameux dépôts rubanés de fer (« BIF ») précambriens, les stromatolithes précambriens exploités par les cimentiers en Afrique, les « marbres rouges » mésozoïques européens dont la teinte liée à des ferro-bactéries sont utilisés depuis des siècles par les architectes, les gisements d’or d’Afrique du Sud plus riches grâce à la médiation bactérienne, certains gisements de plomb, de zinc, de nickel, etc. Tous les indices biologiques laissés dans ces bio-gisements suite aux interactions de microbes et minéraux seront parmi les premiers qui nous révèleront des traces de vie sur d’autres planètes.