Engineering E. coli as part of a living membrane biosensor for organophosphates

Organophosphates are poisonous compounds used in pesticides and chemical weapons, such as nerve gas, that inhibit the natural process of the enzyme acetylcholinesterase (AChE). For soldiers and first responders who may come in to contact with these types of hazardous chemicals, it is important to have the ability to quickly and accurately identify unknown substances. Current technology is either too inaccurate or too complicated to identify these substances in the field. In this thesis, a living membrane biosensor composed of bacterial cellulose produced by Gluconacetobacter xylinus (G. xylinus) and engineered Escherichia coli (E. coli) was developed and tested. Using confocal microscopy, this study demonstrates the ability of bacterial cellulose to act as a scaffold for reporting E. coli cells. It also investigates the use of a cellulose/gelatin composite, which is shown to increase hydration time of the membrane, implying a faster testing procedure. Lastly, E. coli cells were engineered with a plasmid coding for the AChE/ToxR transmembrane protein. Western blot testing implies the production of this protein at high levels of arabinose induction.