Sensitivity of selected bacterial species to UV radiation

Gascón, Jordi; Oubiña, Anna; Pérez-Lezaun, Ana; Urmeneta, Jordi

doi:10.1007/bf00296205

Cited by 65 publications

(62 citation statements)

References 13 publications

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“…The relative radiation tolerance of a given microorganism is defined by the D 37 and D 10 values, reflecting the exposure dosage that causes the population to decrease to a level of 37% or 10% of the initial density, respectively. (21). During this experiment, E. coli BL21 was irradiated and used as a reference point; however, we verified that wild-type E. coli (AB1157) behaved similarly (see Fig.…”

Section: Resultsmentioning

confidence: 61%

Chromatin Organization and Radio Resistance in the Bacterium Gemmata obscuriglobus

et al. 2009

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The organization of chromatin has a major impact on cellular activities, such as gene expression. For bacteria, it was suggested that the spatial organization of the genetic material correlates with transcriptional levels, implying a specific architecture of the chromosome within the cytoplasm. Accordingly, recent technological advances have emphasized the organization of the genetic material within nucleoid structures. Gemmata obscuriglobus, a member of the phylum Planctomycetes, exhibits a distinctive nucleoid structure in which chromatin is encapsulated within a discrete membrane-bound compartment. Here, we show that this soil and freshwater bacterium tolerates high doses of UV and ionizing radiation. Cryoelectron tomography of frozen hydrated sections and electron microscopy of freeze-substituted cells have indicated a more highly ordered condensed-chromatin organization in actively dividing and stationary-phase G. obscuriglobus cells. These three-dimensional analyses revealed a complex network of double membranes that engulf the condensed DNA. Bioinformatics analysis has revealed the existence of a putative component involved in nonhomologous DNA end joining that presumably plays a role in maintaining chromatin integrity within the bacterium. Thus, our observations further support the notion that packed chromatin organization enhances radiation tolerance.

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Section: Resultsmentioning

confidence: 61%

Chromatin Organization and Radio Resistance in the Bacterium Gemmata obscuriglobus

et al. 2009

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“…Deinococcus radiodurans is one of the most radiation tolerant organism known, withstanding 1000x the lethal human radiation dose. UV tolerance experiments show D. radiodurans can survive 400 J m −2 of 254nm radiation without significant loss of viability with appreciable loss of viability occurring around 500-600 J m −2 (Gascón et al 1995). We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3500 times the modern Earth-Sun levels.…”

Section: Discussionmentioning

confidence: 72%

Uv Surface Environment of Earth-Like Planets Orbiting FGKM Stars Through Geological Evolution

Rugheimer

Segura

Kaltenegger

et al. 2015

ApJ

128

253

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The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars at the 1AU equivalent distance for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present day levels at 2.0 Gyr ago, 0.8 Gyr ago and modern Earth (following Kaltenegger et al. 2007). In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern EarthSun levels. A pre-biotic Earth orbiting GJ 581 (M3.5V) receives 300 times less biologically effective radiation, about 2 times modern Earth-Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

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“…In addition to enzymatic DNA repair mechanisms, microbes have evolved to survive UV exposure through other molecular and structural protection and avoidance methods. However, whether these additional methods actually protect the bacterial DNA is widely debated (Mathews & Sistrom, 1959; Dworkin & Stanley, 2006;Gascon et al, 1995; Lewis et al, 1973; Singer & Ames, 1970; Nasium & James, 1978;Cockell, 1998;Arrage et al, 1993a). Iron compounds, sand, desert crust, rock, water, sulfur and sodium chloride have all been found to be natural UVR shields for bacteria (Cockell, 1998;Rothschild & Giver, 2003).…”

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confidence: 99%

Ultraviolet radiation sensitivity in cave bacteria: evidence of adaptation to the subsurface?

Snider¹,

Goin²,

Miller³

et al. 2009

IJS

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We hypothesize that a reduced capacity to withstand or repair cellular damage from ultraviolet radiation may be present in caveadapted microorganisms that never experience such conditions. However, a small number of previous studies have shown that some subsurface bacteria do not show greater sensitivity to ultraviolet radiation (UVR) than surface bacteria. To estimate UVR sensitivity in cave bacteria, bacterial isolates were collected from Carlsbad Cavern, New Mexico, U.S.A., and percent survival following exposure to various UVC and UVA radiation doses was determined. Cave bacteria from Left Hand Tunnel in Carlsbad Cavern and surface bacteria from soil and rocks above Carlsbad Cavern were grown on low and high nutrient media then exposed to 0, 10,000 and 20,000 μWs/ cm 2 of UVR in a laboratory biological safety cabinet. Incubations were conducted at 15°C or 37ºC, in accordance with the isolates' natural temperature environments. In addition, DNA repair capacity was estimated by exposing the organisms to various doses of UVC radiation and measuring survivability. Gram status and pigmentation also were determined. Results showed that most of the cave isolates were more sensitive to UVR than the surface isolates, but survivability data suggest that cave microbes retain some of their capacity to repair UV-induced DNA damage. Selection appears to have favored bacteria that can survive in this low nutrient environment, while not maintaining (or paying the cost of maintaining) unneeded traits such as UVR resistance. Cave bacteria appear to have maintained DNA repair capacity, most likely because of the need to repair damage to their DNA from other environmental stressors found in caves.Keywords: Ultraviolet radiation sensitivity, cave-adaptation, bacteria, subsurface, caves unable to show a correlation between natural levels of radiation exposure and species resistance (Nasim & James, 1978;Arrage et al., 1993a).UV radiation (UVR) at wavelengths shorter than 400 nm is absorbed by DNA and can cause cyclobutane dimer formation, interstrand crosslinking, and other direct and indirect damage to DNA (Nasim & James, 1978;Miller et al., 1999). In addition to enzymatic DNA repair mechanisms, microbes have evolved to survive UV exposure through other molecular and structural protection and avoidance methods. However, whether these additional methods actually protect the bacterial DNA is widely debated (Mathews & Sistrom, 1959; Dworkin & Stanley, 2006;Gascon et al., 1995; Lewis et al., 1973; Singer & Ames, 1970; Nasium & James, 1978;Cockell, 1998;Arrage et al., 1993a). Iron compounds, sand, desert crust, rock, water, sulfur and sodium chloride have all been found to be natural UVR shields for bacteria (Cockell, 1998;Rothschild & Giver, 2003). A well-documented predominance of pigmentation in UVR-resistant species of bacteria suggests the use of carotenoids, yellow, orange and red cellular pigments, as UVR screening agents (Mathews & Sistrom, 1959; Dworkin & Stanley, 2006). UVR screening agents also provide protection from ox...

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Sensitivity of selected bacterial species to UV radiation

Cited by 65 publications

References 13 publications

Chromatin Organization and Radio Resistance in the Bacterium Gemmata obscuriglobus

Chromatin Organization and Radio Resistance in the Bacterium Gemmata obscuriglobus

Uv Surface Environment of Earth-Like Planets Orbiting FGKM Stars Through Geological Evolution

Ultraviolet radiation sensitivity in cave bacteria: evidence of adaptation to the subsurface?

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