Team:Valencia Biocampus/Results2

Are you fermenting?

The experiments with our glucose-sensitive construction were carried out by three different ways: (1) containing only glucose as a carbon source, (2) containing galactose as an extra carbon source and (3) containing sodium acetate as an extra carbon source, since we checked in previous tests that low concentrations of glucose compromised cell growth. All tubes had, in addition to the glucose gradation, also IPTG (see information on the molecular mechanism). For fluorescence intensity (FI) measures cell growth, i.e. OD600, was taken into account. We worked with a 0D600 close to 0.1 in order to be able to use high sensitivity in the fluorimeter.

As you can see in the graphs below, the less glucose you have, the more fluorescence you get. And this results replicate well when galactose (Figure 2) or sodium acetate (Figure 3) were added to the medium as supplementary carbon sources. The threshold for a boost in the fluorescence intensity seems to be 0.1 g/L of glucose, since from this concentration the values get really high. Normal values are 10 g/L, and we got the best results when we added 10^-4 glucose concentration of that of the canonical values.

Figure 1. Fluorescence intensity (FI) normalized by the optical density of the culture (OD) for differents amounts of glucose present in the medium.

Figure 2. Fluorescence intensity (FI) normalized by the optical density of the culture (OD) for differents amounts of glucose in a medium supplemented with 3 g/L galactose.

Figure 3. Fluorescence intensity (FI) normalized by the optical density of the culture (OD) for differents amounts of glucose in a medium supplemented with 3 g/L sodium acetate.