Figure 1: The lactoAid is a bandage containing Lactococcus lactis

The iGEM Groningen team 2014 is creating a bandage containing Lactococcus lactis that produces nisin to destroy gram-positive bacteria. The bandage consists of a top layer that permits air to flow through and keeps the bandage clean, a middle layer of hydrogel that holds the L. lactis, and a bottom layer of higher density hydrogel that allows proteins to pass through but contains the L. lactis to the middle layer. Additionally we wll introduce the excretion of AHL lactonase and Dispersin B, compounds that disrupt quorum sensing and biofilm formation respectively of Staphylococcus aureus and Pseudomonas aeruginosa. To take it even further, the bandage will detect quorum sensing molecules produced by S. aureus and P. aeruginosa. Thus the bandage will excrete nisin and Dispersin B when S. aureus is present and AHL lactonase when P. aeruginosa is present.

Infections in burn wounds are currently only treatable with antibiotics. An increase in antibiotic resistance makes it harder every day to fight these bacteria. In our system L. lactis produces a so-called lantibiotic, nisin. Nisin is effective against a group of gram-positive bacteria such as Staphylococcus aureus and resistance against nisin is hardly ever found and if found, the resistance does not last.

Beside nisin the L. lactis will be able to produce the infection preventing molecules (IPMs) AiiA and DspB. AiiA will disrupt the communication mechanism of the harmful bacteria, this way the bacteria will not cause any trouble because it 'thinks' it is alone. DspB is a molecule that prevents the harmful bacteria to form a layer (biofilm) on the wound. Additionally we want to try to make the bandage 'active' (producing nisin, DspB and AiiA) only when harmful bacteria are present in the wound. The bandage targets Staphyolococcus aureus and Pseudomonas aeruginosa specifically, two bactefria that are a problem in burn wound centres.

Figure 2: Quorum sensing molecules pass from the wound to the lactococcus lactis, in turn IPMs pass from the bandage into the wound.

The design of the bandage is important as well. L. lactis should not be able to get out of the bandage, but the IPMs should be able to reach the wound (See figure 2). Besides containing L. lactis the bandage should allow sufficient oxygen to reach the wound.

Finally, the whole package needs to be able to be stored for quite a while and still work. Therefore L. lactis will be stored as a powder and can be activated with water when the bandage is needed.

We are also investigating the possibilities of having L. lactis produce growth factors to aid in wound healing and to link the detection to the production of a chromoprotein to show when the bandage detects harmful bacteria.