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1.
Crit Rev Biotechnol ; : 1-19, 2023 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-37258417

RESUMO

Civilian and military nuclear programs of several nations over more than 70 years have led to significant quantities of heterogenous solid, organic, and aqueous radioactive wastes bearing actinides, fission products, and activation products. While many physicochemical treatments have been developed to remediate, decontaminate and reduce waste volumes, they can involve high costs (energy input, expensive sorbants, ion exchange resins, chemical reducing/precipitation agents) or can lead to further secondary waste forms. Microorganisms can directly influence radionuclide solubility, via sorption, accumulation, precipitation, redox, and volatilization pathways, thus offering a more sustainable approach to remediation or effluent treatments. Much work to date has focused on fundamentals or laboratory-scale remediation trials, but there is a paucity of information toward field-scale bioremediation and, to a lesser extent, toward biological liquid effluent treatments. From the few biostimulation studies that have been conducted at legacy weapon production/test sites and uranium mining and milling sites, some marked success via bioreduction and biomineralisation has been observed. However, rebounding of radionuclide mobility from (a)biotic scale-up factors are often encountered. Radionuclide, heavy metal, co-contaminant, and/or matrix effects provide more challenging conditions than traditional industrial wastewater systems, thus innovative solutions via indirect interactions with stable element biogeochemical cycles, natural or engineered cultures or communities of metal and irradiation tolerant strains and reactor design inspirations from existing metal wastewater technologies, are required. This review encompasses the current state of the art in radionuclide biogeochemistry fundamentals and bioremediation and establishes links toward transitioning these concepts toward future radioactive effluent treatments.

2.
Front Microbiol ; 15: 1423342, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39109212

RESUMO

Some natural environments on Earth are characterised by high levels of radiation, including naturally radioelement enriched mineral springs in the French Massif Central. Therefore, naturally radioactive mineral springs are interesting ecosystems for understanding how bacterial populations in these springs have adapted to high levels of natural and chronic radioactivity over the very long term. The aim of this study was to analyse the bacterial communities of sediments from five naturally radioactive mineral springs in the French Massif Central, sampled in autumn 2019 and spring 2020, and to observe whether radionuclides, compared to other physicochemical parameters, are drivers of the bacterial community structuring in these extreme environments. Physicochemical measurements showed that two springs, Dourioux and Montagne had high radioelement concentrations/activities (uranium, thorium and radon). Analysis of the structure of the bacterial communities, by next generation sequencing based on 16S rRNA gene sequencing, showed that the presence of radionuclides in Dourioux and Montagne, did not lead to a reduction in bacterial diversity and richness compared to the other springs. However, Dourioux and Montagne were characterised by specific bacterial populations, whose presence correlates with the radioelement concentrations/activities measured in these springs. This suggests that radioelements could partly explain the structuring of bacterial communities in these springs. In addition, several of these operational taxonomic units (OTUs) specific to Dourioux and Montagne, mainly affiliated to Proteobacteria, Firmicutes, Acidobacteria, Actinobacteria, and Bacteroidetes, could be involved in the biogeochemistry of radionuclides through different mechanisms (biosorption, biomineralisation, bioaccumulation, and bioreduction), which would allow the development of other bacterial species sensitive to these metals/radioelements. In particular, the co-occurrence of sulphate and/or iron-reducing bacteria, capable of bioreducing uranium, with fermentative bacteria, releasing sources of organic carbons, reflects associations of bacteria with complementary functions that allow them to grow in this peculiar environment and maintain a high diversity in these extreme environments. This study has provided a better understanding of the structuring of bacterial communities exposed to ionising radiation for thousands of years in naturally radioactive environments.

3.
Sci Total Environ ; 919: 170692, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38325491

RESUMO

This study aimed to assess the potential impact of long-term chronic exposure (69 years) to naturally-occurring radionuclides (RNs) and heavy metals on microbial communities in sediment from a stream flowing through a watershed impacted by an ancient mining site (Rophin, France). Four sediment samples were collected along a radioactivity gradient (for 238U368 to 1710 Bq.Kg-1) characterized for the presence of the bioavailable fractions of radionuclides (226Ra, 210Po), and trace metal elements (Th, U, As, Pb, Cu, Zn, Fe). Results revealed that the available fraction of contaminants was significant although it varied considerably from one element to another (0 % for As and Th, 5-59 % for U). Nonetheless, microbial communities appeared significantly affected by such chronic exposure to (radio)toxicities. Several microbial functions carried by bacteria and related with carbon and nitrogen cycling have been impaired. The high values of fungal diversity and richness observed with increasing downstream contamination (H' = 4.4 and Chao1 = 863) suggest that the community had likely shifted toward a more adapted/tolerant one as evidenced, for example, by the presence of the species Thelephora sp. and Tomentella sp. The bacterial composition was also affected by the contaminants with enrichment in Myxococcales, Acidovorax or Nostocales at the most contaminated points. Changes in microbial composition and functional structure were directly related to radionuclide and heavy metal contaminations, but also to organic matter which also significantly affected, directly or indirectly, bacterial and fungal compositions. Although it was not possible to distinguish the specific effects of RNs from heavy metals on microbial communities, it is essential to continue studies considering the available fraction of elements, which is the only one able to interact with microorganisms.


Assuntos
Metais Pesados , Microbiota , Metais Pesados/toxicidade , Metais Pesados/análise , Bactérias , Radioisótopos/análise , França
4.
Bull Acad Natl Med ; 197(3): 661-74; discussion 674-5, 2013 Mar.
Artigo em Francês | MEDLINE | ID: mdl-25163348

RESUMO

Iron is necessary for cell metabolism, but excess iron can be toxic Iron can generate oxygen free radicals through the Fenton reaction. Iron accumulation has been observed in the retina of patients with age-related macular degeneration (AMD). We have shown its accumulation in photoreceptor segments in two animal models of genetic retinal degeneration (RCS rats and Rd10 mice). In these rodents, hTf, injected intraperitoneally or expressed by genetic modification, delayed photoreceptor degeneration. Our studies highlight the therapeutic potential of Tf in degenerative processes such as retinitis pigmentosa and AMD.


Assuntos
Proteínas Reguladoras de Ferro/metabolismo , Ferro/metabolismo , Retina/metabolismo , Degeneração Retiniana/metabolismo , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Ratos , Degeneração Retiniana/genética , Degeneração Retiniana/patologia
5.
Mol Vis ; 16: 2612-25, 2010 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-21179240

RESUMO

PURPOSE: Retinal degeneration has been associated with iron accumulation in age-related macular degeneration (AMD), and in several rodent models that had one or several iron regulating protein impairments. We investigated the iron concentration and the protective role of human transferrin (hTf) in rd10 mice, a model of retinal degeneration. METHODS: The proton-induced X-ray emission (PIXE) method was used to quantify iron in rd10 mice 2, 3, and 4 weeks after birth. We generated mice with the ß-phosphodiesterase mutation and hTf expression by crossbreeding rd10 mice with TghTf mice (rd10/hTf mice). The photoreceptor loss and apoptosis were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling in 3-week-old rd10/hTf mice and compared with 3-week-old rd10 mice. The neuroprotective effect of hTf was analyzed in 5-day-old rd10 mice treated by intraperitoneal administration with hTf for up to 25 days. The retinal hTf concentrations and the thickness of the outer nuclear layer were quantified in all treated mice at 25 days postnatally. RESULTS: PIXE analysis demonstrated an age-dependent iron accumulation in the photoreceptors of rd10 mice. The rd10/hTf mice had the rd10 mutation, expressed high levels of hTf, and showed a significant decrease in photoreceptor death. In addition, rd10 mice intraperitoneally treated with hTf resulted in the retinal presence of hTf and a dose-dependent reduction in photoreceptor degeneration. CONCLUSIONS: Our results suggest that iron accumulation in the retinas of rd10 mutant mice is associated with photoreceptor degeneration. For the first time, the enhanced survival of cones and rods in the retina of this model has been demonstrated through overexpression or systemic administration of hTf. This study highlights the therapeutic potential of Tf to inhibit iron-induced photoreceptor cell death observed in degenerative diseases such as retinitis pigmentosa and age-related macular degeneration.


Assuntos
Degeneração Retiniana/tratamento farmacológico , Degeneração Retiniana/prevenção & controle , Transferrina/administração & dosagem , Transferrina/uso terapêutico , Animais , Transporte Biológico/efeitos dos fármacos , Modelos Animais de Doenças , Microanálise por Sonda Eletrônica , Humanos , Injeções Intraperitoneais , Ferro/metabolismo , Camundongos , Retina/efeitos dos fármacos , Retina/metabolismo , Retina/patologia , Células Fotorreceptoras Retinianas Cones/efeitos dos fármacos , Células Fotorreceptoras Retinianas Cones/metabolismo , Células Fotorreceptoras Retinianas Cones/patologia , Degeneração Retiniana/patologia , Células Fotorreceptoras Retinianas Bastonetes/efeitos dos fármacos , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Células Fotorreceptoras Retinianas Bastonetes/patologia , Espectrometria por Raios X , Transferrina/farmacologia
6.
FEMS Microbiol Ecol ; 93(8)2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28645185

RESUMO

After the Chernobyl nuclear power plant accident in 1986, contaminated soils, vegetation from the Red Forest and other radioactive debris were buried within trenches. In this area, trench T22 has long been a pilot site for the study of radionuclide migration in soil. Here, we used 454 pyrosequencing of 16S rRNA genes to obtain a comprehensive view of the bacterial and archaeal diversity in soils collected inside and in the vicinity of the trench T22 and to investigate the impact of radioactive waste disposal on prokaryotic communities. A remarkably high abundance of Chloroflexi and AD3 was detected in all soil samples from this area. Our statistical analysis revealed profound changes in community composition at the phylum and OTUs levels and higher diversity in the trench soils as compared to the outside. Our results demonstrate that the total absorbed dose rate by cell and, to a lesser extent the organic matter content of the trench, are the principal variables influencing prokaryotic assemblages. We identified specific phylotypes affiliated to the phyla Crenarchaeota, Acidobacteria, AD3, Chloroflexi, Proteobacteria, Verrucomicrobia and WPS-2, which were unique for the trench soils.


Assuntos
Acidobacteria/isolamento & purificação , Acidente Nuclear de Chernobyl , Chloroflexi/isolamento & purificação , Crenarchaeota/isolamento & purificação , Proteobactérias/isolamento & purificação , Resíduos Sólidos/análise , Verrucomicrobia/isolamento & purificação , Acidobacteria/classificação , Acidobacteria/genética , Sequência de Bases , Chloroflexi/classificação , Chloroflexi/genética , Crenarchaeota/classificação , Crenarchaeota/genética , Proteobactérias/classificação , Proteobactérias/genética , RNA Ribossômico 16S/genética , Resíduos Radioativos/análise , Radioisótopos/análise , Eliminação de Resíduos , Análise de Sequência de DNA , Solo , Microbiologia do Solo , Poluentes Radioativos do Solo/análise , Ucrânia , Verrucomicrobia/classificação , Verrucomicrobia/genética
7.
J Hazard Mater ; 285: 285-93, 2015 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-25528226

RESUMO

Although uranium (U) is naturally found in the environment, soil remediation programs will become increasingly important in light of certain human activities. This work aimed to identify U(VI) detoxification mechanisms employed by a bacteria strain isolated from a Chernobyl soil sample, and to distinguish its active from passive mechanisms of interaction. The ability of the Microbacterium sp. A9 strain to remove U(VI) from aqueous solutions at 4 °C and 25 °C was evaluated, as well as its survival capacity upon U(VI) exposure. The subcellular localisation of U was determined by TEM/EDX microscopy, while functional groups involved in the interaction with U were further evaluated by FTIR; finally, the speciation of U was analysed by TRLFS. We have revealed, for the first time, an active mechanism promoting metal efflux from the cells, during the early steps following U(VI) exposure at 25 °C. The Microbacterium sp. A9 strain also stores U intracellularly, as needle-like structures that have been identified as an autunite group mineral. Taken together, our results demonstrate that this strain exhibits a high U(VI) tolerance based on multiple detoxification mechanisms. These findings support the potential role of the genus Microbacterium in the remediation of aqueous environments contaminated with U(VI) under aerobic conditions.


Assuntos
Actinobacteria/efeitos dos fármacos , Poluentes Radioativos do Solo/farmacologia , Urânio/farmacologia , Actinobacteria/crescimento & desenvolvimento , Actinobacteria/metabolismo , Actinobacteria/ultraestrutura , Adsorção , Carga Bacteriana , Acidente Nuclear de Chernobyl , Microscopia Eletrônica de Transmissão , Fosfatos/análise , Fosfatos/metabolismo , Microbiologia do Solo , Poluentes Radioativos do Solo/análise , Poluentes Radioativos do Solo/química , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , Ucrânia , Urânio/análise , Urânio/química
8.
Invest Ophthalmol Vis Sci ; 43(2): 537-45, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11818402

RESUMO

PURPOSE: To determine whether iron homeostasis disorder accompanies retinal degeneration in Royal College of Surgeons (RCS) rats. METHODS: The presence of iron was revealed directly by proton-induced X-ray emission (PIXE) and indirectly by electron microscopy (EM). Ferritin, transferrin (Tf), and transferrin receptor (Tf-R) were localized by immunohistochemistry. Ferritin and Tf proteins were analyzed by Western blot analysis. Comparative study of Tf-R content was performed by slot-blot analysis and ferritin content was evaluated by enzyme-linked immunosorbent assay (ELISA). Ferritin and Tf-R expression was studied by reverse transcription-polymerase chain reaction (RT-PCR) and Tf expression by in situ hybridization (ISH). All studies were performed in RCS and control retinas from postnatal days (PN)20 to PN55. RESULTS: PIXE analysis showed iron accumulation in outer retina of RCS rats in a time-dependent manner. EM studies revealed irregular iron inclusions on partially degenerated outer segments (OS) of photoreceptors and lamellar whorls at PN35 and very large iron deposits on membranes from a debris layer at PN55. No such deposits were found in the inner retina. Ferritin and Tf-R expression and protein levels seemed to be unaffected in the inner part of the retina. Iron accumulation was preceded by Tf degradation, as revealed by immunohistochemistry and Western blot analysis. Tf mRNA was detected in RCS rat retinal pigment epithelium (RPE) at all stages studied. CONCLUSIONS: This study presents the first evidence for a correlation of iron homeostasis imbalance with the neurodegenerative state of the retina in RCS rats. The iron imbalance is not the underlying genetic defect but is the result of impaired RPE-photoreceptor interaction, which leads to debris accumulation and subsequent blockage of the outer retina's iron delivery pathway. The increase of iron in the photoreceptor area may enhance the vulnerability of cells to oxidative stress.


Assuntos
Distúrbios do Metabolismo do Ferro/metabolismo , Ferro/metabolismo , Fagocitose , Degeneração Retiniana/metabolismo , Segmento Externo da Célula Bastonete/metabolismo , Animais , Western Blotting , Microanálise por Sonda Eletrônica , Ensaio de Imunoadsorção Enzimática , Ferritinas/genética , Ferritinas/metabolismo , Técnica Indireta de Fluorescência para Anticorpo , Homeostase , Hibridização In Situ , Distúrbios do Metabolismo do Ferro/patologia , Epitélio Pigmentado Ocular/metabolismo , Epitélio Pigmentado Ocular/ultraestrutura , RNA Mensageiro/metabolismo , Ratos , Ratos Mutantes , Receptores da Transferrina/genética , Receptores da Transferrina/metabolismo , Degeneração Retiniana/patologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Segmento Externo da Célula Bastonete/ultraestrutura , Fatores de Tempo , Transferrina/metabolismo
9.
Appl Microbiol Biotechnol ; 76(2): 467-72, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17619187

RESUMO

Washed cell suspensions of the anaerobic hyperthermophilic archaea Thermococcus pacificus and Thermoproteus uzoniensis and the anaerobic thermophilic gram-positive bacteria Thermoterrabacterium ferrireducens and Tepidibacter thalassicus reduced technetium [(99)Tc(VII)], supplied as soluble pertechnetate with molecular hydrogen as an electron donor, forming highly insoluble Tc(IV)-containing grayish-black precipitate. Apart from molecular hydrogen, T. ferrireducens reduced Tc(VII) with lactate, glycerol, and yeast extract as electron donors, and T. thalassicus reduced it with peptone. Scanning electron microscopy and X-ray microanalysis of cell suspensions of T. ferrireducens showed the presence of Tc-containing particles attached to the surfaces of non-lysed cells. This is the first report on the reduction in Tc(VII) by thermophilic microorganisms of the domain Bacteria and by archaea of the phylum Euryarchaeota.


Assuntos
Archaea/metabolismo , Bactérias/metabolismo , Oxirredução , Tecnécio/metabolismo
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