<b><i>RETRACTED:</i></b> Twenty-Three Species of Hypobarophilic Bacteria Recovered from Diverse Ecosystems Exhibit Growth under Simulated Martian Conditions at 0.7 kPa

SchuergerAndrew, C; NicholsonWayne, L

doi:10.1089/ast.2015.1394

Cited by 12 publications

(3 citation statements)

References 39 publications

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“…nov. , was isolated from the frigid anoxic waters of Ace Lake Antarctica (Franzmann et al, 1991). Carnobacteria are among microbes most likely to exist in austere simulated Martian environments (Schuerger and Nicholson, 2016). Vagococci diverged from carnobacteria, and remain generally associated with marine animals (Michel et al, 2007; Svanevik and Lunestad, 2011; Buller, 2014).…”

Section: Discussionmentioning

confidence: 99%

Tracing the Enterococci from Paleozoic Origins to the Hospital

Lebreton

Manson

Saavedra

et al. 2017

Cell

241

240

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Summary We examined the evolutionary history of leading multidrug resistant hospital pathogens, the enterococci, to their origin hundreds of millions of years ago. Our goal was to understand why, among the vast diversity of gut flora, enterococci are so well adapted to the modern hospital environment. Molecular clock estimation, together with analysis of their environmental distribution, phenotypic diversity and concordance with host fossil records, place the origins of the enterococci around the time of animal terrestrialization – 425 – 500 MYA. Speciation appears to parallel the diversification of hosts, including the rapid emergence of new enterococcal species following the End Permian Extinction. Major drivers of speciation include changing carbohydrate availability in the host gut. Life on land would have selected for the precise traits that now allow pathogenic enterococci to survive desiccation, starvation and disinfection in the modern hospital; foreordaining their emergence as leading hospital pathogens.

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Section: Discussionmentioning

confidence: 99%

Tracing the Enterococci from Paleozoic Origins to the Hospital

Lebreton

Manson

Saavedra

et al. 2017

Cell

241

240

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“…The lower limit of pressure for life is not well-determined either, but the main obstacle seems to be rather associated with desiccation and low water activity rather than pressure itself ( Diaz and Schulze-Makuch, 2006 ). Schuerger and Nicholson (2016) exposed many different organisms to Mars surface pressure conditions of about 0.6 kPa, and showed that many species were surviving at this low pressure, even species not known as hypobarophiles. Thus, as a first working assumption we postulate that pressure conditions, at least as experienced on a terrestrial planet, such as Earth, will not constitute a major problem for alien life.…”

Section: Physicochemical Limits Of Lifementioning

confidence: 99%

The Adaptability of Life on Earth and the Diversity of Planetary Habitats

Schulze‐Makuch

Airo

Schirmack³

2017

Front. Microbiol.

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The evolutionary adaptability of life to extreme environments is astounding given that all life on Earth is based on the same fundamental biochemistry. The range of some physicochemical parameters on Earth exceeds the ability of life to adapt, but stays within the limits of life for other parameters. Certain environmental conditions such as low water availability in hyperarid deserts on Earth seem to be close to the limit of biological activity. A much wider range of environmental parameters is observed on planetary bodies within our Solar System such as Mars or Titan, and presumably even larger outside of our Solar System. Here we review the adaptability of life as we know it, especially regarding temperature, pressure, and water activity. We use then this knowledge to outline the range of possible habitable environments for alien planets and moons and distinguish between a variety of planetary environment types. Some of these types are present in our Solar System, others are hypothetical. Our schematic categorization of alien habitats is limited to life as we know it, particularly regarding to the use of solvent (water) and energy source (light and chemical compounds).

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“…The pressure of the thin and dry stratospheric air around 25–38 km above sea level (ASL) is roughly equivalent to the surface pressure on Mars (0.5–1 kPa). The stratosphere is also a cold and extremely dry environment with elevated levels of ionizing and non-ionizing radiation (Adams et al, 2007 ; Dachev, 2013 ; Schuerger and Nicholson, 2016 ). Relative humidity levels can drop below 1%, and temperatures in the lower stratosphere regularly reach −100°C.…”

Section: Introductionmentioning

confidence: 99%

Stratosphere Conditions Inactivate Bacterial Endospores from a Mars Spacecraft Assembly Facility

et al. 2017

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Every spacecraft sent to Mars is allowed to land viable microbial bioburden, including hardy endospore-forming bacteria resistant to environmental extremes. Earth's stratosphere is severely cold, dry, irradiated, and oligotrophic; it can be used as a stand-in location for predicting how stowaway microbes might respond to the martian surface. We launched E-MIST, a high-altitude NASA balloon payload on 10 October 2015 carrying known quantities of viable Bacillus pumilus SAFR-032 (4.07 × 107 spores per sample), a radiation-tolerant strain collected from a spacecraft assembly facility. The payload spent 8 h at ∼31 km above sea level, exposing bacterial spores to the stratosphere. We found that within 120 and 240 min, spore viability was significantly reduced by 2 and 4 orders of magnitude, respectively. By 480 min, <0.001% of spores carried to the stratosphere remained viable. Our balloon flight results predict that most terrestrial bacteria would be inactivated within the first sol on Mars if contaminated spacecraft surfaces receive direct sunlight. Unfortunately, an instrument malfunction prevented the acquisition of UV light measurements during our balloon mission. To make up for the absence of radiometer data, we calculated a stratosphere UV model and conducted ground tests with a 271.1 nm UVC light source (0.5 W/m2), observing a similarly rapid inactivation rate when using a lower number of contaminants (640 spores per sample). The starting concentration of spores and microconfiguration on hardware surfaces appeared to influence survivability outcomes in both experiments. With the relatively few spores that survived the stratosphere, we performed a resequencing analysis and identified three single nucleotide polymorphisms compared to unexposed controls. It is therefore plausible that bacteria enduring radiation-rich environments (e.g., Earth's upper atmosphere, interplanetary space, or the surface of Mars) may be pushed in evolutionarily consequential directions. Key Words: Planetary protection—Stratosphere—Balloon—Mars analog environment—E-MIST payload—Bacillus pumilus SAFR-032. Astrobiology 17, 337–350.

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RETRACTED: Twenty-Three Species of Hypobarophilic Bacteria Recovered from Diverse Ecosystems Exhibit Growth under Simulated Martian Conditions at 0.7 kPa

Cited by 12 publications

References 39 publications

Tracing the Enterococci from Paleozoic Origins to the Hospital

Tracing the Enterococci from Paleozoic Origins to the Hospital

The Adaptability of Life on Earth and the Diversity of Planetary Habitats

Stratosphere Conditions Inactivate Bacterial Endospores from a Mars Spacecraft Assembly Facility

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