Publications by authors named "Julien Farasin"

Bacteria often thrive in surface-attached communities, where they can form biofilms affording them multiple advantages. In this sessile form, fluid flow is a key component of their environments, renewing nutrients and transporting metabolic products and signaling molecules. It also controls colonization patterns and growth rates on surfaces, through bacteria transport, attachment and detachment.

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Ferriphaselus amnicola GF-20 is the first Fe-oxidizing bacterium isolated from the continental subsurface. It was isolated from groundwater circulating at 20 m depth in the fractured-rock catchment observatory of Guidel-Ploemeur (France). Strain GF-20 is a neutrophilic, iron- and thiosulfate-oxidizer and grows autotrophically.

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  • Bacteria at acid mine drainage sites play a crucial role in water remediation by converting arsenite to arsenate, which helps in the removal of arsenic from contaminated water.
  • After exposure to arsenite, certain bacterial strains can develop resistant variants, particularly when grown in biofilms, and these variants increase in prevalence with higher arsenite concentrations.
  • The study identified that genes related to DNA repair were upregulated in resistant bacteria, and multiple mutations accumulated, particularly in a genomic island associated with arsenic resistance, shedding light on bacterial adaptation and genome evolution in toxic environments.
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  • Fe-oxidizing bacteria from the family Gallionellaceae play a crucial role in the iron cycle in freshwater environments, particularly in areas with varying redox conditions.
  • Researchers analyzed the genetic diversity of these bacteria in an aquifer characterized by different redox transition zones, discovering 15 new draft genomes and identifying a dominant genus they propose to name 'Candidatus Houarnoksidobacter'.
  • The study found that distinct microbial communities of Gallionellaceae exist in subsurface and surface zones, despite continual groundwater movement, suggesting that factors like oxygen diffusion and groundwater mixing are key influences on their diversity.
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The sustainability of ground-source geothermal systems can be severely impacted by microbially mediated clogging processes. Biofouling of water wells by hydrous ferric oxide is a widespread problem. Although the mechanisms and critical environmental factors associated with clogging development are widely recognized, effects of mixing processes within the wells and time scales for clogging processes are not well characterized.

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Several studies have suggested the existence of a close relationship between antibiotic-resistant phenotypes and resistance to other toxic compounds such as heavy metals, which involve co-resistance or cross-resistance mechanisms. A metagenomic library was previously constructed in Escherichia coli with DNA extracted from the bacterial community inhabiting an acid mine drainage (AMD) site highly contaminated with heavy metals. Here, we conducted a search for genes involved in antibiotic resistance using this previously constructed library.

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  • Thiomonas bacteria are found in arsenic-contaminated waters like acid mine drainage and play a role in cleaning up arsenic through biofilm formation.
  • The study examined three Thiomonas strains, discovering that two favored biofilm formation while one preferred motility when exposed to arsenite.
  • Using RNA-seq, the research investigated gene expression related to biofilm formation in Thiomonas sp. CB2, enhancing understanding of how these bacteria adapt to extreme environments.
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The acid mine drainage (AMD) impacted creek of the Carnoulès mine (Southern France) is characterized by acid waters with a high heavy metal content. The microbial community inhabiting this AMD was extensively studied using isolation, metagenomic and metaproteomic methods, and the results showed that a natural arsenic (and iron) attenuation process involving the arsenite oxidase activity of several Thiomonas strains occurs at this site. A sensitive quantitative Selected Reaction Monitoring (SRM)-based proteomic approach was developed for detecting and quantifying the two subunits of the arsenite oxidase and RpoA of two different Thiomonas groups.

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The acid mine drainage (AMD) in Carnoulès (France) is characterized by the presence of toxic metals such as arsenic. Several bacterial strains belonging to the Thiomonas genus, which were isolated from this AMD, are able to withstand these conditions. Their genomes carry several genomic islands (GEIs), which are known to be potentially advantageous in some particular ecological niches.

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Article Synopsis
  • Acid mine drainage (AMD) poses a toxic threat to life due to elements like arsenic, but Thiomonas bacteria can survive by oxidizing arsenite.
  • * Researchers sequenced the genomes of six Thiomonas isolates from the Carnoulès AMD to understand their adaptive traits, comparing them to other strains like Tm. arsenitoxydans and Tm. intermedia.
  • * The analysis revealed significant genomic rearrangements and over 20 genomic islands across the strains, indicating that arsenic-related genes have evolved differently, enhancing their survival in arsenic-rich environments.
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  • Biofilms play a crucial role in resisting toxic compounds, with recent studies highlighting their formation and mechanisms in medical and health contexts.
  • The organic matrix of biofilms protects cells from environmental stresses, while certain cells adapt their metabolism, leading to the emergence of persister cells that can survive harsh conditions.
  • Multispecies biofilms enhance survival through metabolic interactions and promote horizontal gene transfer, aiding microbial resilience and potentially driving evolution.
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Prokaryotic viruses play a major role in the microbial ecology and evolution. However, the virosphere associated with deep-sea hydrothermal ecosystems remains largely unexplored. Numerous instances of lateral gene transfer have contributed to the complex and incongruent evolutionary history of Thermotogales, an order well represented in deep-sea hydrothermal vents.

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