This part contains the ''fimH'' adhesin under control of a titratable rhamnose promoter. The FimH protein is a subunit of a naturally occurring structure in some strains of ''E. coli'' called type 1 pili. These hairlike appendages typically manifest as organelles on the surface of pathogenic E. coli which are responsible for urinary tract infections in humans. The FimH adhesin is found at the tip of the pilus, and binds naturally to the sugar mannose. This part can be cotransformed with <partinfo>BBa_K1850013</partinfo>, which contains the rest of the ''fim'' operon, and induced to produce type 1 pili.
This part contains the ''fimH'' adhesin under control of a titratable rhamnose promoter. The FimH protein is a subunit of a naturally occurring structure in some strains of ''E. coli'' called type 1 pili. These hairlike appendages typically manifest as organelles on the surface of pathogenic E. coli which are responsible for urinary tract infections in humans. The FimH adhesin is found at the tip of the pilus, and binds naturally to the sugar mannose. This part can be cotransformed with <partinfo>BBa_K1850013</partinfo>, which contains the rest of the ''fim'' operon, and induced to produce type 1 pili.
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This part also contains a HisTag inserted into ''fimH''. HisTags have the ability to bind to nickel, and our goal was to express them on the tip of the pills. We used a nickel agglutination assay to detect whether our bacteria could bind to Nickel-NTA magnetic microbeads and aggregate them or remain in suspension. OD standardized volumes of induced and uninduced cultures were added to an equivalent volume of suspended Nickel-NTA beads, agitated, and allowed to rest. We found that our His Tag fimH plasmids were able to agglutinate nickel beads, while a Wild Type control was not. This suggests control over adhesion to Nickel-NTA magnetic beads.
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The ability to remove nickel particles from a solution could be extremely useful in waste water purification and pollution remediation. This experimental setup is almost identical to how we imagine our nickel binding system could be used in the real world. A sample of our E. coli could be added to a contaminated sample of water, the sample could be agitated, and any heavy-metal contaminants would fall out of solution with the bacterial clump. Future work can elaborate the toolbox of contaminant-binding peptides so that a range of harmful products could be purified. Furthermore, this process might just as easily be applied to mining valuable minerals from water, where binding peptides for rare and precious materials could be added to fimH, the resulting induced cultures mixed with a water sample containing the material of interest, and the bacterial clump extracted as if “mined” out of water. Our biological approach could be superior to existing mining techniques which require toxic chemicals and generate environmentally hazardous waste products. With biological extraction, the only waste would be a completely biodegradable and present in the water anyway (bacteria are present everywhere). These directions are areas of ongoing research in the lab.
