Background

RcsB (biobrick [http://partsregistry.org/Part:BBa_K200000 BBa_K200000] is the gene responsible for generating a colanic acid capsule around our bacteria. Having a colanic acid capsule around them will protect them from being degraded by the high acidic nature of the stomach environment.

Aim

Here, as proof of concept, we have designed a simple experiment that will show that colanic acid has a protective effect on our growing bacteria in acidic environments (simulating gastric conditions). The method is described below.

Experimental Method

In a multiple well plate, 2 different types of cell cultures were grown, both containing the [http://partsregistry.org/Part:BBa_I13522 BBa_I13522] construct, which is a constitutive promoter expressing GFP. The differences were:

• Some cultures contained colanic acid (chemically induced by p-Fluoro-L-phenylalanine (FPA))
• Some cultures did not contain colanic acid.

Growth rate of the cell cultures and levels of GFP expression were monitored over time, at different Ph values in order to decide if induction using colanic acid provides extra protection to the construct.

Results analysis

Effect of Ph on non-colanic acid cells

Effect of Ph on colanic acid and non-colanic acid cells

Conclusion