Team:Penn/LightActivatedLysis

We then wanted to prove that our pDawn-ClyA construct was able to lyse mammalian cells in a light-dependent manner. To assess this, we plated BL21 bacteria transformed with pDawn-ClyA or pDawn-mCherry on Columbia Agar plates supplemented with 5% Sheep Blood (BD). These plates are used to qualitatively detect hemolytic activity in bacteria by visually confirming lysis through a color change in the media as the blood cells are lysed. After plating the bacteria, cultures were grown in non-inducing conditions at 37C until visible colonies were present (~12 hours). Plates were then grown at 25C under either inducing or non-inducing conditions for 24 hours and imaged. These results are visible in Figure 4.

pDawn-mCherry Dark

pDawn-mCherry Light

pDawn-His-ClyA Dark

pDawn-His-ClyA Light

In order to further develop our system for future in vivo therapeutic applications, we transformed Nissle 1917 with pDawn-mCherry to see if we could implement our system into a non-pathogenic strain of E. coli. We repeated our initial experiments and achieved light-dependent gene expression in Nissle 1917 for the first time ever. We are now hoping to clone in our pDawn-ClyA construct to show that Nissle 1917 is capable of light-dependent lysis of mammalian cells. Stay tuned!

Figure 5