Safety and responsibility

Fault tree

In the consequence tree, we consider here the Iron Coli as if it already produced the siderophores, and thus have iron under a chelated form. We imagine then, what Iron Coli may become after their action in the jejunum.

(1) Free iron needs to be chelated by siderophores to be internalized by bacteria. Thus, a higher concentration could favor any bacterial growth. However, the pathogenicity of harmful strains is characterized by the expression of a higher amount of siderophores, thus positively selecting them among others.

(2) If Iron Coli dies after it released its siderophores without internalizaing them after chelation, both pathogenic and non-pathogenic strains have access to the chelated iron. This should not favor one or another.

(3) In case Iron Coli survives, the expression of siderophores in the presence of iron is a suicidal behaviour if the ion comes to be in excessive amount. We hypothesize that the bacteria may lose the plasmids for its own survival because the selective pressure is lost. However, if the overexpression of siderophores appears as beneficial for bacterial growth, the strain has an advantage compared to the rest of the microbiome.

(4) As expected, mutations and genetic information sharing among bacteria are the main concerns for the patients and the general public. We can see through this fault tree that this scenario is the less likely to happen.

Conclusion

To minimize the risks for our iron chelating bacteria, it is very clear that the best case scenario is the death of our bacteria. Thus, if Iron Coli survives the jejunum, the best solution is to overcome this issue by implementing a death switch.