The research on Engineered Living Materials (ELMs) is picking up speed, thanks to the creation of a new priority program 2451 funded by the German Research Foundation. ELMs combine living cells with structural materials to create dynamic, multifunctional systems. Within this context, our cooperation project “ContainELMs” in the priority program focuses on a critical, yet underexplored aspect: biocontainment. While previous studies on hybrid ELMs have demonstrated their general functionality, they failed to safely contain living cells. 

This project aims to bridge the gap by developing core-shell fiber structures that combine genetic and physical biocontainment. The Advanced Polymers and Biomaterials group at IFG, KIT, will design these fibers to house bacteria within a controlled microenvironment for a specified duration. Simultaneously, the Bioprogrammable Materials group at INM, Uni Saarland, will genetically engineer the bacteria to survive within this tailored environment by creating a genetic survival switch.

To achieve this, model (E.coli) and non-model bacteria (L.plantarum) will be encoded with genetic switches that tightly regulate the expression of survival-supporting genes in the presence of an inducer or synthetic ligand. The survival-switches will be made with both auxotrophy and toxin-antitoxin systems and eventually combined to improve their biocontainment efficacy. Auxotrophy strategies include complementing essential gene knockouts under genetic switch control and introducing synthetic ligand dependency via CRISPR-Cas9 editing. Toxin-antitoxin systems involve constitutive toxin expression with antitoxin regulation by genetic switches. The effectiveness of these biocontainment methods will be tested by evaluating survival under non-permissive conditions, escape frequencies, and combining strategies for enhanced robustness, with potential genome integration for stability improvements.