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2.
Res Microbiol ; 166(3): 205-14, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25753102

RESUMO

Pseudomonas xanthomarina S11 is an arsenite-oxidizing bacterium isolated from an arsenic-contaminated former gold mine in Salsigne, France. This bacterium showed high resistance to arsenite and was able to oxidize arsenite to arsenate at concentrations up to 42.72 mM As[III]. The genome of this strain was sequenced and revealed the presence of three ars clusters. One of them is located on a plasmid and is organized as an "arsenic island" harbouring an aio operon and genes involved in phosphorous metabolism, in addition to the ars genes. Neither the aioXRS genes nor a specific sigma-54-dependent promoter located upstream of aioBA genes, both involved in regulation of arsenite oxidase expression in other arsenite-oxidizing bacteria, could be identified in the genome. This observation is in accordance with the fact that no difference was observed in expression of arsenite oxidase in P. xanthomarina S11, whether or not the strain was grown in the presence of As[III].


Assuntos
Arsênio/metabolismo , Proteínas de Bactérias/genética , Oxirredutases/genética , Oxirredutases/metabolismo , Pseudomonas/genética , Arseniatos/metabolismo , Arsênio/farmacologia , ATPases Transportadoras de Arsenito/genética , ATPases Transportadoras de Arsenito/metabolismo , Arsenitos/metabolismo , Arsenitos/farmacologia , Proteínas de Bactérias/metabolismo , Sequência de Bases , DNA Bacteriano , Farmacorresistência Bacteriana , França , Regulação Bacteriana da Expressão Gênica , Mineração , Óperon , Oxirredução , Filogenia , Plasmídeos , Pseudomonas/enzimologia , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/isolamento & purificação
3.
ISME J ; 6(7): 1391-402, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22237547

RESUMO

Euglena mutabilis is a photosynthetic protist found in acidic aquatic environments such as peat bogs, volcanic lakes and acid mine drainages (AMDs). Through its photosynthetic metabolism, this protist is supposed to have an important role in primary production in such oligotrophic ecosystems. Nevertheless, the exact contribution of E. mutabilis in organic matter synthesis remains unclear and no evidence of metabolite secretion by this protist has been established so far. Here we combined in situ proteo-metabolomic approaches to determine the nature of the metabolites accumulated by this protist or potentially secreted into an AMD. Our results revealed that the secreted metabolites are represented by a large number of amino acids, polyamine compounds, urea and some sugars but no fatty acids, suggesting a selective organic matter contribution in this ecosystem. Such a production may have a crucial impact on the bacterial community present on the study site, as it has been suggested previously that prokaryotes transport and recycle in situ most of the metabolites secreted by E. mutabilis. Consequently, this protist may have an indirect but important role in AMD ecosystems but also in other ecological niches often described as nitrogen-limited.


Assuntos
Ecossistema , Euglena/isolamento & purificação , Euglena/metabolismo , Mineração , Ácidos/metabolismo , França , Metabolômica , Fotossíntese
4.
Res Microbiol ; 162(9): 877-87, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21704701

RESUMO

Arsenic-resistant prokaryote diversity is far from being exhaustively explored. In this study, the arsenic-adapted prokaryotic community present in a moderately arsenic-contaminated site near Sainte-Marie-aux-Mines (France) was characterized, using metaproteomic and 16S rRNA-encoding gene amplification. High prokaryotic diversity was observed, with a majority of Proteobacteria, Acidobacteria and Bacteroidetes, and a large archaeal community comprising Euryarchaeaota and Thaumarchaeota. Metaproteomic analysis revealed that Proteobacteria, Planctomycetes and Cyanobacteria are among the active bacteria in this ecosystem. Taken together, these results highlight the unsuspected high diversity of the arsenic-adapted prokaryotic community, with some phyla never having been described in highly arsenic-exposed sites.


Assuntos
Archaea/genética , Arsênio/metabolismo , Bactérias/genética , Sedimentos Geológicos/microbiologia , Consórcios Microbianos/fisiologia , Proteômica , Rios/microbiologia , Adaptação Fisiológica , Archaea/classificação , Archaea/isolamento & purificação , Archaea/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/metabolismo , Biodiversidade , DNA Arqueal/análise , DNA Arqueal/genética , DNA Bacteriano/análise , DNA Bacteriano/genética , Ecossistema , Poluentes Ambientais/metabolismo , França , Transferência Genética Horizontal , Filogenia , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/análise , RNA Ribossômico 16S/genética
5.
ISME J ; 5(11): 1735-47, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21562598

RESUMO

By their metabolic activities, microorganisms have a crucial role in the biogeochemical cycles of elements. The complete understanding of these processes requires, however, the deciphering of both the structure and the function, including synecologic interactions, of microbial communities. Using a metagenomic approach, we demonstrated here that an acid mine drainage highly contaminated with arsenic is dominated by seven bacterial strains whose genomes were reconstructed. Five of them represent yet uncultivated bacteria and include two strains belonging to a novel bacterial phylum present in some similar ecosystems, and which was named 'Candidatus Fodinabacter communificans.' Metaproteomic data unravelled several microbial capabilities expressed in situ, such as iron, sulfur and arsenic oxidation that are key mechanisms in biomineralization, or organic nutrient, amino acid and vitamin metabolism involved in synthrophic associations. A statistical analysis of genomic and proteomic data and reverse transcriptase-PCR experiments allowed us to build an integrated model of the metabolic interactions that may be of prime importance in the natural attenuation of such anthropized ecosystems.


Assuntos
Arsênio/metabolismo , Bactérias/genética , Bactérias/metabolismo , Ecossistema , Metagenômica , Proteômica , Bactérias/classificação , Bactérias/isolamento & purificação , Ferro/metabolismo , Mineração , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Enxofre/metabolismo
6.
BMC Microbiol ; 10: 53, 2010 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-20167112

RESUMO

BACKGROUND: Both the speciation and toxicity of arsenic are affected by bacterial transformations, i.e. oxidation, reduction or methylation. These transformations have a major impact on environmental contamination and more particularly on arsenic contamination of drinking water. Herminiimonas arsenicoxydans has been isolated from an arsenic- contaminated environment and has developed various mechanisms for coping with arsenic, including the oxidation of As(III) to As(V) as a detoxification mechanism. RESULTS: In the present study, a differential transcriptome analysis was used to identify genes, including arsenite oxidase encoding genes, involved in the response of H. arsenicoxydans to As(III). To get insight into the molecular mechanisms of this enzyme activity, a Tn5 transposon mutagenesis was performed. Transposon insertions resulting in a lack of arsenite oxidase activity disrupted aoxR and aoxS genes, showing that the aox operon transcription is regulated by the AoxRS two-component system. Remarkably, transposon insertions were also identified in rpoN coding for the alternative N sigma factor (sigma54) of RNA polymerase and in dnaJ coding for the Hsp70 co-chaperone. Western blotting with anti-AoxB antibodies and quantitative RT-PCR experiments allowed us to demonstrate that the rpoN and dnaJ gene products are involved in the control of arsenite oxidase gene expression. Finally, the transcriptional start site of the aoxAB operon was determined using rapid amplification of cDNA ends (RACE) and a putative -12/-24 sigma54-dependent promoter motif was identified upstream of aoxAB coding sequences. CONCLUSION: These results reveal the existence of novel molecular regulatory processes governing arsenite oxidase expression in H. arsenicoxydans. These data are summarized in a model that functionally integrates arsenite oxidation in the adaptive response to As(III) in this microorganism.


Assuntos
Regulação Bacteriana da Expressão Gênica , Oxalobacteraceae/genética , Oxalobacteraceae/metabolismo , Oxirredutases/genética , Sequência de Aminoácidos , Arsenitos/metabolismo , Arsenitos/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases , Sequência Conservada , Perfilação da Expressão Gênica/métodos , Genes Bacterianos , Redes e Vias Metabólicas , Dados de Sequência Molecular , Mutação , Óperon , Oxalobacteraceae/enzimologia , Oxirredutases/biossíntese , Oxirredutases/metabolismo , Percepção de Quorum/efeitos dos fármacos , Percepção de Quorum/genética , Alinhamento de Sequência , Transcrição Gênica/efeitos dos fármacos
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