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First Detailed Microscopy Evidence of Bacteria at the Lower Size Limit of Life

Scientists have captured the first detailed microscopy images of ultra-small bacteria that are believed to be about as small as life can get. The research was led by scientists from the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California, Berkeley. The existence of ultra-small bacteria has been debated for two decades, but there hasn't been a comprehensive electron microscopy and DNA-based description of the microbes until now.
The cells have an average volume of 0.009 cubic microns (one micron is one millionth of a meter). About 150 of these bacteria could fit inside an Escherichia coli cell and more than 150,000 cells could fit onto the tip of a human hair.

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Bacterium from Canadian High Arctic and life on Mars

The temperature in the permafrost on Ellesmere Island in the Canadian high Arctic is nearly as cold as that of the surface of Mars. So the recent discovery by a McGill University led team of scientists of a bacterium that is able to thrive at -15C, the coldest temperature ever reported for bacterial growth, is exciting. The bacterium offers clues about some of the necessary preconditions for microbial life on both the Saturn moon Enceladus and Mars, where similar briny subzero conditions are thought to exist.
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Planococcus halocryophilus Or1
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Title: Bacterial growth at -15C; molecular insights from the permafrost bacterium Planococcus halocryophilus Or1.
Authors: Mykytczuk NC, Foote SJ, Omelon CR, Southam G, Greer CW, Whyte LG.

Planococcus halocryophilus strain Or1, isolated from high Arctic permafrost, grows and divides at -15C, the lowest temperature demonstrated to date, and is metabolically active at -25C in frozen permafrost microcosms. To understand how P. halocryophilus Or1 remains active under the subzero and osmotically dynamic conditions that characterize its native permafrost habitat, we investigated the genome, cell physiology and transcriptomes of growth at -15C and 18% NaCl compared with optimal (25C) temperatures. Subzero growth coincides with unusual cell envelope features of encrustations surrounding cells, while the cytoplasmic membrane is significantly remodelled favouring a higher ratio of saturated to branched fatty acids. Analyses of the 3.4Mbp genome revealed that a suite of cold and osmotic-specific adaptive mechanisms are present as well as an amino acid distribution favouring increased flexibility of proteins. Genomic redundancy within 17% of the genome could enable P. halocryophilus Or1 to exploit isozyme exchange to maintain growth under stress, including multiple copies of osmolyte uptake genes (Opu and Pro genes). Isozyme exchange was observed between the transcriptome data sets, with selective upregulation of multi-copy genes involved in cell division, fatty acid synthesis, solute binding, oxidative stress response and transcriptional regulation. The combination of protein flexibility, resource efficiency, genomic plasticity and synergistic adaptation likely compensate against osmotic and cold stresses. These results suggest that non-spore forming P. halocryophilus Or1 is specifically suited for active growth in its Arctic permafrost habitat (ambient temp. ~-16C), indicating that such cryoenvironments harbour a more active microbial ecosystem than previously thought.

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Last life on Earth: microbes will rule the far future

The last life on Earth will perish in 2.8 billion years, scorched by the dying sun as it swells to become a red giant. For about a billion years before that, the only living things will be single-celled organisms drifting in isolated pools of hot, salty water.
A grim outlook, sure, but there's a silver lining for today's alien-hunters. The model that predicts these pockets of life on future Earth also hints that the habitability of planets around other stars is more varied than previously believed, offering new hope for finding life in unlikely places.

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Title: "Probing the limits of extremophilic life in extraterrestrial environment-simulated experiments"
Authors: Claudia Lage, Gabriel Dalmaso, Lia Teixeira, Amanda Bendia, Ivan Paulino-Lima, Douglas Galante, Eduardo Janot-Pacheco, Ximena Abrevaya, Armando Aza-Bustos, Vivian Pellizari, Alexandre Rosado

The results obtained in these experiments have revealed a remarkable resistance of extremophilic bacteria and archaea against different radiation sources (VUV, solar wind simulants, X rays) whenever protected by microsized carbonaceus grains. Altogether, the collected data suggest the interesting possibility of the existence of microbial life beyond Earth and its transfer among habitable bodies, which we have called microlithopanspermia.

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CU-Boulder-led team finds microbes in extreme environment on South American volcanoes

A team led by the University of Colorado Boulder looking for organisms that eke out a living in some of the most inhospitable soils on Earth has found a hardy few.
A new DNA analysis of rocky soils in the Martian-like landscape on some volcanoes in South America has revealed a handful of bacteria, fungi and other rudimentary organisms called archaea, which seem to have a different way of converting energy than their cousins elsewhere in the world.

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Title: Absence of detectable arsenate in DNA from arsenate-grown GFAJ-1 cells.
Authors: M. L. Reaves, S. Sinha, J. D. Rabinowitz, L. Kruglyak, R. J. Redfield

A strain of Halomonas bacteria, GFAJ-1, has been reported to be able to use arsenate as a nutrient when phosphate is limiting, and to specifically incorporate arsenic into its DNA in place of phosphorus. However, we have found that arsenate does not contribute to growth of GFAJ-1 when phosphate is limiting and that DNA purified from cells grown with limiting phosphate and abundant arsenate does not exhibit the spontaneous hydrolysis expected of arsenate ester bonds. Furthermore, mass spectrometry showed that this DNA contains only trace amounts of free arsenate and no detectable covalently bound arsenate.

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Researchers Identify Mysterious Life Forms in the Extreme Deep Sea

A summer research expedition organized by scientists at Scripps Institution of Oceanography at UC San Diego has led to the identification of gigantic amoebas at one of the deepest locations on Earth.
During a July 2011 voyage to the Pacific Ocean's Mariana Trench, the deepest region on the planet, Scripps researchers and National Geographic engineers deployed untethered free-falling/ascending landers equipped with digital video and lights to search the largely unexplored region. The team documented the deepest known existence of xenophyophores, single-celled animals exclusively found in deep-sea environments. Xenophyophores are noteworthy for their size, with individual cells often exceeding 10 centimeters, their extreme abundance on the seafloor and their role as hosts for a variety of organisms.

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Alien bacteria could breed in extreme 'hypergravity'

If alien life is out there, it may be able to exploit more-extreme environments than scientists think, because huge gravitational forces don't seem to pose much of a problem for microbes.
Several different species of bacteria can survive and reproduce in "hypergravity" more than 400,000 times stronger than that of the Earth, a new study reports. The find suggests that alien life could take root in a wide range of conditions -- and that it could survive the high G-forces imposed by meteorite impacts and ejections, making the exchange of life between planets a distinct possibility.

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ISRO finds micro life in earth's atmosphere

In a major breakthrough, Indian Space Research Organisation (ISRO) has discovered micro-life, not known to exist on earth's surface, in the atmosphere, internationally acclaimed astrophysicist Jayant Vishnu Narlikar disclosed here on Wednesday. Delivering a lecture on "the search for micro-life in the earth's atmosphere" at Pt. Ravishankar Shukla University here, Mr Narlikar, the founder-director of the Inter-University Centre for Astronomy and Astrophysics (IUCCA), referred to two successful balloon tests done in 2001 and 2005 under the guidance of the ISRO. He said air samples collected by releasing the balloons up to a height of 41 km in 2005 had confirmed the presence of micro-organisms not known otherwise on earth.
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