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From 2010.igem.org

An Engineering Approach to an Environmental Biosensor for Multiple Fish Toxins

We are using a co-design approach to construct a multiple-compound biosensor that detects heavy metals (arsenic, mercury, copper) in aquatic environments. This chart describes the device logic that will be implemented:

This logic will be implemented in three different designs. One of the approaches utilizes the operator sites of regulatory promoters, hybridizing two promoters’ operator sites into a single co-sensing promoter. In order for the hybrid promoter to initiate transcription, two target metals that control the operator sites must be present. Since, the hybrid promoters are attached to a single fluorescent protein, the detection of both metals can be measured using fluorescence.

The second approach utilizes fluorescent protein complementation. When a target metal is detected by a cell, it will transcribe a fragment of a fluorescent protein. Upon translation, the portions of the fluorescent proteins will bond together and fluoresce, reporting the presence of the two target metals.

In the third approach, each of the metals directly induces the production of a corresponding fluorescent protein. Fluorescence spectroscopy is used to separate out the wavelengths of each fluorescent protein, which will indicate what compounds are present in the environment.

In all three designs we are amplifying the signal that each E. coli cell emits once it is exposed to the target metal using a quorum sensing system. Each cell releases a signal when exposed to the target metal, which is then recognized by neighboring cells. A fluorescent protein is attached to the promoter that recognizes the signal, establishing a more rapid, binary-like response time in the system. The overall goal of the project is to create a set of interchangeable inputs and outputs serving a wide variety of applications such as bioremediation machinery.

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