title: "NiCo Buster": engineering E. coli for fast and efficient capture of cobalt and nickel.
abstract: BACKGROUND
  Metal contamination is widespread and results from natural geogenic and constantly increasing anthropogenic sources (mainly mining and extraction activities, electroplating, battery and steel manufacturing or metal finishing). Consequently, there is a growing need for methods to detoxify polluted ecosystems. Industrial wastewater, surface water and ground water need to be decontaminated to alleviate the contamination of soils and sediments and, ultimately, the human food chain. In nuclear power plants, radioactive metals are produced; these metals need to be removed from effluents before they are released into the environment, not only for pollution prevention but also for waste minimization. Many physicochemical methods have been developed for metal removal from aqueous solutions, including chemical coagulation, adsorption, extraction, ion exchange and membrane separation; however, these methods are generally not metal selective. Bacteria, because they contain metal transporters, provide a potentially competitive alternative to the current use of expensive and high-volume ion-exchange resins.
  
  
  RESULTS
  The feasibility of using bacterial biofilters as efficient tools for nickel and cobalt ions specific remediation was investigated. Among the factors susceptible to genetic modification in Escherichia coli, specific efflux and sequestration systems were engineered to improve its metal sequestration abilities. Genomic suppression of the RcnA nickel (Ni) and cobalt (Co) efflux system was combined with the plasmid-controlled expression of a genetically improved version of a specific metallic transporter, NiCoT, which originates from Novosphingobium aromaticivorans. The resulting strain exhibited enhanced nickel (II) and cobalt (II) uptake, with a maximum metal ion accumulation of 6 mg/g bacterial dry weight during 10 min of treatment. A synthetic adherence operon was successfully introduced into the plasmid carrying the improved NiCoT transporter, conferring the ability to form thick biofilm structures, especially when exposed to nickel and cobalt metallic compounds.
  
  
  CONCLUSIONS
  This study demonstrates the efficient use of genetic engineering to increase metal sequestration and biofilm formation by E. coli. This method allows Co and Ni contaminants to be sequestered while spatially confining the bacteria to an abiotic support. Biofiltration of nickel (II) and cobalt (II) by immobilized cells is therefore a promising option for treating these contaminants at an industrial scale.
authors.affiliation: iGEM team INSA Lyon, Plateforme de Biologie de Synthèse, Département Biosciences, INSA Lyon, 69621 Villeurbanne Cedex, France.|Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon I, CNRS, MAP, UMR5240, Villeurbanne F-69621, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Duprey
authors.affiliation: iGEM team INSA Lyon, Plateforme de Biologie de Synthèse, Département Biosciences, INSA Lyon, 69621 Villeurbanne Cedex, France.
authors.forename: Viviane
authors.initials: V
authors.lastname: Chansavang
authors.affiliation: iGEM team INSA Lyon, Plateforme de Biologie de Synthèse, Département Biosciences, INSA Lyon, 69621 Villeurbanne Cedex, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Frémion
authors.affiliation: iGEM team INSA Lyon, Plateforme de Biologie de Synthèse, Département Biosciences, INSA Lyon, 69621 Villeurbanne Cedex, France.
authors.forename: Clémence
authors.initials: C
authors.lastname: Gonthier
authors.affiliation: Université de Lyon, INSA-Lyon, LGCIE, Villeurbanne F-69621, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Louis
authors.affiliation: Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon I, CNRS, MAP, UMR5240, Villeurbanne F-69621, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Lejeune
authors.affiliation: Université de Lyon, INSA-Lyon, LGCIE, Villeurbanne F-69621, France.
authors.forename: Fanny
authors.initials: F
authors.lastname: Springer
authors.affiliation: Université de Lyon, INSA-Lyon, LGCIE, Villeurbanne F-69621, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Desjardin
authors.affiliation: Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon I, CNRS, MAP, UMR5240, Villeurbanne F-69621, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Rodrigue
authors.affiliation: Université de Lyon, INSA-Lyon, LGCIE, Villeurbanne F-69621, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Dorel
keywords: Biofilm; Biofilter; Bioremediation; Cobalt; NiCoT; Nickel; Synthetic biology
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