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The Microguards: Overview
Nowadays, there are numerous industrial processes that use microorganisms such as Escherichia coli and Saccharomyces cerevisiae to produce compounds of interest, like insulin, ethanol and various enzymes. The success of these processes depends on the absence of contamination by other microorganisms in the culture medium. The presence of contaminants in a fermentation process reduces its efficiency due to competition between the contaminant and the fermentative organism, causing losses of 5 to 10% of the gross production. To try to solve this problem, the aim of our project is to engineer strains of E. coli and S. cerevisiae that are able to recognize and destroy contaminants during industrial processes.
The Coliguard: Our Model
We want our engineered E. coli to be able to recognize and destroy contaminants in culture medium. Since we want our bacteria to show maximum efficiency during the industrial process, we decided to create two different lineages of E. coli: the worker lineage – responsible for executing the industrial process – and the killer lineage – responsible for detecting and killing the contaminants. Both lineages are going to be simultaneously present in the culture medium, but their proportion will vary due to the presence or absence of contaminants. In the absence of contaminants, the amount of worker cells will be much higher than the number of killer ones, so that the industrial process will occur at its maximum efficiency. In the presence of contaminants, killer cells will induce surrounding worker cells to differentiate into more killer cells in a transient manner. After elimination of contaminants by the killer lineage, the proportion of worker and killer cells will return to its original rate.
Based on our model, we divided the project into three subparts.
- Recognition mechanism
- Differentiation mechanism
- Killing mechanism
1) Recognition mechanism
Our idea is based on the premise that the engineered E. coli most be able to recognize contaminants in the culture medium as non-self. As most bacterial species produces AI2 (auto inducer 2) as a secondary metabolite, we decided to use this compound as a recognition factor. Our E. coli will be an AI2- strain and won´t produce native AI2. The presence of AI2 in the culture medium indicates the presence of contaminants, which will be recognized by an AI2 sensitive promoter present in our E. coli.
The Yeastguard: Expandind
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