“NiCo Buster”: engineering E. coli for fast and efficient capture of cobalt and nickel

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

iGEM REPORT: Gotta Detect ‘Em All: a multi-STI sensor based on aptamers

/International audienceNowadays, STIs constitute a major public health issue. Indeed, treatments are often started too late because of belated diagnosis resulting in health problems, such as sterility. If prevention is probably the most effective action one can take to prevent the spread of STIs, early detection could help limit their deleterious effects. In this work, a new diagnosis approach based on aptamers is presented. Bound to paper, they allow the detection of HIV and Hepatitis B biomarkers from a blood sample. The associated device is composed of an anchor, the streptavidin protein, allowing the fixation of the aptamer to the paper via biotin (see graphical abstract). With this system, the HIV-1 Reverse Transcriptase (BBa_K1934060 and BBa_K1934061: protein subunits p51 and p66) and HBsAg (surface antigen of Hepatitis B) are specifically targeted. Then, the biomarker/aptamer complex is detected by two methods. The first one is based on fluorescence. As a proof of concept, a paired ATP/aptamer was used and enabled to successfully detect ATP up to 10 µmol.L-1. However, the signal was not detectable with naked eyes or with a cell phone equipped with blue and green filters either. Therefore, a lateral flow assay with nano-sized latex black beads was tested. This second technique showed that a protein biomarker, such as thrombin, could be complexed with latex beads coated with aptamers, in liquid. Finally, the ultimate step, migration of the latex beads inside paper, needs further optimization. Moreover, to easily handle several STI-tests on a single paper strip, an innovative bio-sourced PLA casing was designed and 3D printed to offer an additional intuitive user-interface

iGEM REPORT: Gotta Detect ‘Em All: a multi-STI sensor based on aptamers

/International audienceNowadays, STIs constitute a major public health issue. Indeed, treatments are often started too late because of belated diagnosis resulting in health problems, such as sterility. If prevention is probably the most effective action one can take to prevent the spread of STIs, early detection could help limit their deleterious effects. In this work, a new diagnosis approach based on aptamers is presented. Bound to paper, they allow the detection of HIV and Hepatitis B biomarkers from a blood sample. The associated device is composed of an anchor, the streptavidin protein, allowing the fixation of the aptamer to the paper via biotin (see graphical abstract). With this system, the HIV-1 Reverse Transcriptase (BBa_K1934060 and BBa_K1934061: protein subunits p51 and p66) and HBsAg (surface antigen of Hepatitis B) are specifically targeted. Then, the biomarker/aptamer complex is detected by two methods. The first one is based on fluorescence. As a proof of concept, a paired ATP/aptamer was used and enabled to successfully detect ATP up to 10 µmol.L-1. However, the signal was not detectable with naked eyes or with a cell phone equipped with blue and green filters either. Therefore, a lateral flow assay with nano-sized latex black beads was tested. This second technique showed that a protein biomarker, such as thrombin, could be complexed with latex beads coated with aptamers, in liquid. Finally, the ultimate step, migration of the latex beads inside paper, needs further optimization. Moreover, to easily handle several STI-tests on a single paper strip, an innovative bio-sourced PLA casing was designed and 3D printed to offer an additional intuitive user-interface

iGEM REPORT: Gotta Detect ‘Em All: a multi-STI sensor based on aptamers

/International audienceNowadays, STIs constitute a major public health issue. Indeed, treatments are often started too late because of belated diagnosis resulting in health problems, such as sterility. If prevention is probably the most effective action one can take to prevent the spread of STIs, early detection could help limit their deleterious effects. In this work, a new diagnosis approach based on aptamers is presented. Bound to paper, they allow the detection of HIV and Hepatitis B biomarkers from a blood sample. The associated device is composed of an anchor, the streptavidin protein, allowing the fixation of the aptamer to the paper via biotin (see graphical abstract). With this system, the HIV-1 Reverse Transcriptase (BBa_K1934060 and BBa_K1934061: protein subunits p51 and p66) and HBsAg (surface antigen of Hepatitis B) are specifically targeted. Then, the biomarker/aptamer complex is detected by two methods. The first one is based on fluorescence. As a proof of concept, a paired ATP/aptamer was used and enabled to successfully detect ATP up to 10 µmol.L-1. However, the signal was not detectable with naked eyes or with a cell phone equipped with blue and green filters either. Therefore, a lateral flow assay with nano-sized latex black beads was tested. This second technique showed that a protein biomarker, such as thrombin, could be complexed with latex beads coated with aptamers, in liquid. Finally, the ultimate step, migration of the latex beads inside paper, needs further optimization. Moreover, to easily handle several STI-tests on a single paper strip, an innovative bio-sourced PLA casing was designed and 3D printed to offer an additional intuitive user-interface

iGEM REPORT: Gotta Detect ‘Em All: a multi-STI sensor based on aptamers

/International audienceNowadays, STIs constitute a major public health issue. Indeed, treatments are often started too late because of belated diagnosis resulting in health problems, such as sterility. If prevention is probably the most effective action one can take to prevent the spread of STIs, early detection could help limit their deleterious effects. In this work, a new diagnosis approach based on aptamers is presented. Bound to paper, they allow the detection of HIV and Hepatitis B biomarkers from a blood sample. The associated device is composed of an anchor, the streptavidin protein, allowing the fixation of the aptamer to the paper via biotin (see graphical abstract). With this system, the HIV-1 Reverse Transcriptase (BBa_K1934060 and BBa_K1934061: protein subunits p51 and p66) and HBsAg (surface antigen of Hepatitis B) are specifically targeted. Then, the biomarker/aptamer complex is detected by two methods. The first one is based on fluorescence. As a proof of concept, a paired ATP/aptamer was used and enabled to successfully detect ATP up to 10 µmol.L-1. However, the signal was not detectable with naked eyes or with a cell phone equipped with blue and green filters either. Therefore, a lateral flow assay with nano-sized latex black beads was tested. This second technique showed that a protein biomarker, such as thrombin, could be complexed with latex beads coated with aptamers, in liquid. Finally, the ultimate step, migration of the latex beads inside paper, needs further optimization. Moreover, to easily handle several STI-tests on a single paper strip, an innovative bio-sourced PLA casing was designed and 3D printed to offer an additional intuitive user-interface

iGEM REPORT: Gotta Detect ‘Em All: a multi-STI sensor based on aptamers

/International audienceNowadays, STIs constitute a major public health issue. Indeed, treatments are often started too late because of belated diagnosis resulting in health problems, such as sterility. If prevention is probably the most effective action one can take to prevent the spread of STIs, early detection could help limit their deleterious effects. In this work, a new diagnosis approach based on aptamers is presented. Bound to paper, they allow the detection of HIV and Hepatitis B biomarkers from a blood sample. The associated device is composed of an anchor, the streptavidin protein, allowing the fixation of the aptamer to the paper via biotin (see graphical abstract). With this system, the HIV-1 Reverse Transcriptase (BBa_K1934060 and BBa_K1934061: protein subunits p51 and p66) and HBsAg (surface antigen of Hepatitis B) are specifically targeted. Then, the biomarker/aptamer complex is detected by two methods. The first one is based on fluorescence. As a proof of concept, a paired ATP/aptamer was used and enabled to successfully detect ATP up to 10 µmol.L-1. However, the signal was not detectable with naked eyes or with a cell phone equipped with blue and green filters either. Therefore, a lateral flow assay with nano-sized latex black beads was tested. This second technique showed that a protein biomarker, such as thrombin, could be complexed with latex beads coated with aptamers, in liquid. Finally, the ultimate step, migration of the latex beads inside paper, needs further optimization. Moreover, to easily handle several STI-tests on a single paper strip, an innovative bio-sourced PLA casing was designed and 3D printed to offer an additional intuitive user-interface