Carotenoid Pigmentation in Antarctic Heterotrophic Bacteria as a Strategy to Withstand Environmental Stresses

Dieser, Markus; Greenwood, Mark C.; Foreman, Christine M.

doi:10.1657/1938-4246-42.4.396

Cited by 163 publications

(129 citation statements)

References 51 publications

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“…had previously been isolated from the LH source (Niederberger et al 2010) but most of the isolated species have also been found in nearby GH and CP springs (Perreault et al 2008), as well as permafrost from Eureka (Steven et al 2008), and in Antarctic sea ice brine (Junge et al 1998). The majority of the isolated channel strains were also pigmented; a common adaptive strategy in many cold environment species that may serve several functions including cryoand solar radiation protection, light-harvesting, and antioxidative activity (Dieser et al 2010;Mueller et al 2005).…”

Section: Discussionmentioning

confidence: 99%

Microbial diversity and activity in hypersaline high Arctic spring channels

et al. 2012

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Lost Hammer (LH) spring is a unique hypersaline, subzero, perennial high Arctic spring arising through thick permafrost. In the present study, the microbial and geochemical characteristics of the LH outflow channels, which remain unfrozen at C-18°C and are more aerobic/ less reducing than the spring source were examined and compared to the previously characterized spring source environment. LH channel sediments contained greater microbial biomass (*100-fold) and greater microbial diversity reflected by the 16S rRNA clone libraries. Phylotypes related to methanogenesis, methanotrophy, sulfur reduction and oxidation were detected in the bacterial clone libraries while the archaeal community was dominated by phylotypes most closely related to THE ammonia-oxidizing Thaumarchaeota. The cumulative percent recovery of 14 Cacetate mineralization in channel sediment microcosms exceeded *30% and *10% at 5 and -5°C, respectively, but sharply decreased at -10°C( B1%). Most bacterial isolates (Marinobacter, Planococcus, and Nesterenkonia spp.) were psychrotrophic, halotolerant, and capable of growth at -5°C. Overall, the hypersaline, subzero LH spring channel has higher microbial diversity and activity than the source, and supports a variety of niches reflecting the more dynamic and heterogeneous channel environment.

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Section: Discussionmentioning

confidence: 99%

Microbial diversity and activity in hypersaline high Arctic spring channels

et al. 2012

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“…b-keto-acyl carrier proteins, including KAS-II and two copies of KAS-III were also found and are key to the synthesis and regulation of the straight and branched-chain lipid ratios in the cell membrane, as is found in C. psychrerythreae (Methé et al, 2005). It is also possible that carotenoid production, linked to cold adaptation in numerous polar microbes (Dieser et al, 2010), may contribute to adjustments in membrane fluidity under low temperature conditions (Jagannadham et al, 2000). The P. halocryophilus Or1 genome encodes synthesis primarily for the carotenoid phytoene (colorless) that is likely used in the secondary production of neurosporene (yelloworange) and lycopene (red-orange) through the activity of phytoene desaturases to impart the bright orange coloration observed in P. halocryophilus Or1 cultures.…”

Section: Genome Analysesmentioning

confidence: 93%

Bacterial growth at −15 °C; molecular insights from the permafrost bacterium Planococcus halocryophilus Or1

et al. 2013

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Planococcus halocryophilus strain Or1, isolated from high Arctic permafrost, grows and divides at À 15 1C, the lowest temperature demonstrated to date, and is metabolically active at À 25 1C 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 À 15 1C and 18% NaCl compared with optimal (25 1C) temperatures. Subzero growth coincides with unusual cell envelope features of encrustations surrounding cells, while the cytoplasmic membrane is significantly remodeled favouring a higher ratio of saturated to branched fatty acids. Analyses of the 3.4 Mbp 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. B À 16 1C), indicating that such cryoenvironments harbor a more active microbial ecosystem than previously thought.

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“…Also soils contain various organics, including pigments and microbial's growth autoregulators. It is shown that these substances play an important role in the stress tolerance of microorganisms [18,[78][79][80][81]. There is also information on the higher radioresistance of microorganisms in soils with high concentrations of humus, but these data are contradictory [82].…”

Section: Irradiation Of Pure Bacterial Cultures With Accelerated Elecmentioning

confidence: 99%

Survivability of Soil and Permafrost Microbial Communities after Irradiation with Accelerated Electrons under Simulated Martian and Open Space Conditions

et al. 2018

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Abstract:One of the prior current astrobiological tasks is revealing the limits of microbial resistance to extraterrestrial conditions. Much attention is paid to ionizing radiation, since it can prevent the preservation and spread of life outside the Earth. The aim of this research was to study the impact of accelerated electrons (~1 MeV) as component of space radiation on microbial communities in their natural habitat-the arid soil and ancient permafrost, and also on the pure bacterial cultures that were isolated from these ecotopes. The irradiation was carried out at low pressure (~0.01 Torr) and low temperature (−130 • C) to simulate the conditions of Mars or outer space. High doses of 10 kGy and 100 kGy were used to assess the effect of dose accumulation in inactive and hypometabolic cells, depending on environmental conditions under long-term irradiation estimated on a geological time scale. It was shown that irradiation with accelerated electrons in the applied doses did not sterilize native samples from Earth extreme habitats. The data obtained suggests that viable Earth-like microorganisms can be preserved in the anabiotic state for at least 1.3 and 20 million years in the regolith of modern Mars in the shallow subsurface layer and at a 5 m depth, respectively. In addition, the results of the study indicate the possibility of maintaining terrestrial like life in the ice of Europa at a 10 cm depth for at least~170 years or for at least 400 thousand years in open space within meteorites. It is established that bacteria in natural habitat has a much higher resistance to in situ irradiation with accelerated electrons when compared to their stability in pure isolated cultures. Thanks to the protective properties of the heterophase environment and the interaction between microbial populations even radiosensitive microorganisms as members of the native microbial communities are able to withstand very high doses of ionizing radiation.

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Carotenoid Pigmentation in Antarctic Heterotrophic Bacteria as a Strategy to Withstand Environmental Stresses

Cited by 163 publications

References 51 publications

Microbial diversity and activity in hypersaline high Arctic spring channels

Microbial diversity and activity in hypersaline high Arctic spring channels

Bacterial growth at −15 °C; molecular insights from the permafrost bacterium Planococcus halocryophilus Or1

Survivability of Soil and Permafrost Microbial Communities after Irradiation with Accelerated Electrons under Simulated Martian and Open Space Conditions

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