We hacked E.coli’s acid resistance module in three places to achieve the production of a safe acid resistant capsule.
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<b>Acid Resistant Polymer – Colanic acid:</b>
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E.coli naturally produces a harmless acid–resistant polymer known as colanic acid. Colanic acid is a polymer of glucose, galactose and glucuronic acid. By tapping into the pathway that initiates colanic acid biosynthesis, we can turn on its production via the modulation of a transcription factor encoded by a gene called RcsB.
In nature, colanic acid acts as a binding agent between individual cells over which a biofilm can be formed. While colanic acid itself is harmless, biofilm formation is associated with a number of virulence factors. To prevent biofilm formation from occurring, we have tapped into a second pathway such that our cells become locked into colanic acid production. The gene responsible for preventing biofilm formation is a transcription factor encoded by a gene called YgiV.
In nature, colanic acid is associated with but not attached to the cell surface. To facilitate whole cell encapsulation, we have modified a third pathway to fix the colanic acid to the surface of the cell. This involves the over–production of an enzyme called Rfal.
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Module 2 - Acid Resistance Overview
