Project description:Thermomacidophilic archaea, such as Metallosphaera sedula, are lithoautotrophs that occupy metal-rich environments. In previous studies, a M. sedula mutant lacking the primary copper efflux transporter, CopA, became copper sensitive. In contrast, the basis for supra-normal copper resistance remained unclear in the spontaneous M. sedula mutant, CuR1. Here, transcriptomic analysis of copper-shocked cultures indicated that CuR1 had a unique regulatory response to metal challenge corresponding to up-regulation of 55 genes. Genome re-sequencing identified 17 confirmed mutations unique to CuR1 that were likely to change gene function. Of these, 12 mapped to genes with annotated function associated with transcription, metabolism or transport. These mutations included 7 non-synonymous substitutions, 4 insertions and 1 deletion. One of the insertion mutations mapped to pseudogene, Msed_1517, and extended its reading frame an additional 209 amino acids. The extended mutant allele was identified as a homolog of Pho4, a family of phosphate symporters that include the bacterial PitA proteins. Orthologs of this allele were apparent in related extremely thermoacidophilic species, suggesting M. sedula was naturally lacking this gene. Phosphate transport studies combined with physiologic analysis demonstrated M. sedula PitA was a low affinity high velocity secondary transporter implicated in copper resistance and arsenate sensitivity. Genetic analysis demonstrated spontaneous arsenate resistant mutants derived from CuR1 all underwent mutation in pitA and non-selectively became copper resistant. Taken together, these results point to archaeal PitA as a key requirement for the increased metal resistance of strain CuR1 and its accelerated capacity for copper bioleaching. The study comprises 5 samples, described in detail below. WT_CuR1: Differential transcriptional response of Metallosphaera sedula DSM 5348, WT, to the supra-normal copper resistant spontaneous Metallosphaera sedula mutant, CuR1 under normal growth conditions. This experiment was done to analyze the differential transcription of WT cells compared with CuR1 cells at mid log phase. WT-15_CuR1-15: Differential transcription of Metallosphaera cells under sub-inhibitory copper challenge (2.0 mM). This experiment was done to analyze the differential transcription of Metallosphaera sedula WT and CuR1 15 minutes post copper challenge. The copper cultures were harvested 15 minutes after the shock. WT-60_CuR1-60: Differential transcription of Metallosphaera cells under sub-inhibitory copper challenge (2.0 mM). This experiment was done to analyze the differential transcription of Metallosphaera sedula WT and CuR1 60 minutes post copper challenge. The copper cultures were harvested 60 minutes after the shock. WT-15_WT-60: Differential transcription of Metallosphaera cells under sub-inhibitory copper challenge (2.0 mM). This experiment was done to analyze the differential transcription of Metallosphaera sedula WT 15 and 60 minutes post copper challenge. The copper cultures were harvested 15 and 60 minutes after the shock, respectively. CuR1-15_CuR1-60: Differential transcription of Metallosphaera cells under sub-inhibitory copper challenge (2.0 mM). This experiment was done to analyze the differential transcription of Metallosphaera sedula CuR1 15 and 60 minutes post copper challenge. The copper cultures were harvested 15 and 60 minutes after the shock, respectively.

Project description:Chemical contamination is a common threat to biota thriving in estuarine and coastal ecosystems. In particular, trace metals tend to accumulate and exert deleterious effects on small invertebrates such as zooplankton, which are essential trophic links between phytoplankton and higher-level consumers in aquatic food webs. Beyond the direct effects of the contamination, we hypothesized that metal exposure could also affect the zooplankton microbiota, which in turn might further impair host fitness. To assess this assumption, copepods (Eurytemora affinis) were sampled in the oligo-mesohaline zone of the Seine estuary and exposed to dissolved copper (25 µg.L-1) over a 72-hour time period. Copepod response to copper treatment was assessed by determining transcriptomic changes in E. affinis along with shifts in its microbiota. Unexpectedly, very few genes were differentially expressed in copper-treated copepods compared to controls, with most of the reported differences involving genes upregulated in males compared to females. In contrast, copper increased the taxonomic diversity indices of the microbiota and resulted in substantial compositional changes at both the phyla and genus levels. Phylogenetic reconstruction of the microbiota further suggested that copper mitigated phylogenetic relatedness of taxa at the basal tree structure of the phylogeny, whereas it strengthened it at the terminal branches. Increased terminal phylogenetic clustering in copper-treated copepods concurred with higher proportions of bacterial genera previously identified as copper resistant (e.g., Pseudomonas, Acinetobacter, and Alkanindiges) and a higher relative abundance of the copA gene encoding a periplasmic inducible multi-copper oxidase. Overall, these results revealed very contrasting responses of E. affinis and its microbiota to copper exposure. The enrichment in micro-organisms likely to perform copper sequestration and/or enzymatic transformation processes, underlines here the need to follow the microbial component during the evaluation of the vulnerability of the zooplankton to the metallic stress.

Project description:Pf-5 is an important biocontrol strain of Pseudomonas fluorsecens, that improves plant growth, mainly via the production of secondary metabolites and growth/colonisation competition. Copper is a broad-spectrum antimicrobial that is effective against bacteria, fungi and even viruses in soluble forms such as copper sulfate and to a lesser extent in solid form, such as copper surfaces. Copper sulfate is commonly sprayed on food crops to increase yield and is becoming more routinely used due to the increasing problem of resistance to standard pesticides. Thus, an obvious question that remains is: what effect is this introduced copper having on these important biocontrol strains? First, the phenotypic effects of copper on carbon utilisation and pH tolerance was tested using Biolog. Interestingly, the ability of Pf-5 to utilise amino acids as a sole carbon source was largely unaltered, but the presence of copper completely eliminated the utilisation of carbohydrates or fatty acids, and diminished the use of carboxylic acids and amines. This could be explained by copper-mediated disruptions of enzymes in metabolic pathways, such as the TCA cycle. The effect on gene expression was examined using reverse transcriptomics, which established molecular bases for the phenotypic results, and confirmed some known mechanisms for copper resistance, efflux and transporter proteins, and highlighted the delicate interplay with cellular control of iron, as well as uncovered the interesting relationship between integrated bacteriophage and copper as a molecular switch. The integrated phage, Prophage 01, was downregulated in the presence of copper and when this phage was activated with Mitomycin C, the copper appeared to stop the phage from going into lytic cycle and protected lysis of the cells. Prophage 01 is integrated between the housekeeping genes mutS and cinA and is conserved throughout many Pseudomonas. However, only Pf-5, out of the 10 strains tested seemed to be protected from cell lysis by copper, indicating that Prophage 01 in Pf-5 has unique features that interact with Cu.

Project description:Pf-5 is an important biocontrol strain of Pseudomonas fluorsecens, that improves plant growth, mainly via the production of secondary metabolites and growth/colonisation competition. Copper is a broad-spectrum antimicrobial that is effective against bacteria, fungi and even viruses in soluble forms such as copper sulfate and to a lesser extent in solid form, such as copper surfaces. Copper sulfate is commonly sprayed on food crops to increase yield and is becoming more routinely used due to the increasing problem of resistance to standard pesticides. Thus, an obvious question that remains is: what effect is this introduced copper having on these important biocontrol strains? First, the phenotypic effects of copper on carbon utilisation and pH tolerance was tested using Biolog. Interestingly, the ability of Pf-5 to utilise amino acids as a sole carbon source was largely unaltered, but the presence of copper completely eliminated the utilisation of carbohydrates or fatty acids, and diminished the use of carboxylic acids and amines. This could be explained by copper-mediated disruptions of enzymes in metabolic pathways, such as the TCA cycle. The effect on gene expression was examined using reverse transcriptomics, which established molecular bases for the phenotypic results, and confirmed some known mechanisms for copper resistance, efflux and transporter proteins, and highlighted the delicate interplay with cellular control of iron, as well as uncovered the interesting relationship between integrated bacteriophage and copper as a molecular switch. The integrated phage, Prophage 01, was downregulated in the presence of copper and when this phage was activated with Mitomycin C, the copper appeared to stop the phage from going into lytic cycle and protected lysis of the cells. Prophage 01 is integrated between the housekeeping genes mutS and cinA and is conserved throughout many Pseudomonas. However, only Pf-5, out of the 10 strains tested seemed to be protected from cell lysis by copper, indicating that Prophage 01 in Pf-5 has unique features that interact with Cu. Two-condition experiment, where normal culture in rich medium versus cell treated with CuSO4. 3 biological replicates including 3 technical replicates for one of the biological replicates and 2 technical replicates for another of biological replicates. Swap-dye experiments were performed.

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