Project Description

BacillaFilla, an engineered Bacillus subtilis, aims to repair cracks in concrete, which can cause catastrophic structural failure. BacillaFilla would be applied to structures by spraying onto their surface.

BacillaFilla swims deep into the cracks. Repair is effected by production of CaCO₃, filamentous Bacillus subtilis cells and levan. CaCO₃ expands at the same rate as concrete, making it the ideal filler. Filamentous Bacillus subtilis cells have similar tensile strength to the synthetic fibres used in fibre-reinforced concrete, and provide reinforcement. Levan glues CaCO₃ and filamentous cells in place.

B. subtilis 168 sporulates, making it ideal for storage and transportation. The cells are naturally tolerant to concrete's high pH.

We designed a swarming BioBrick part for repairing B. subtilis 168's defective swrA and sfp genes and regaining motility. At the end of the crack the quorum sensing peptide subtilin triggers a co-ordinated population response from a subtilin-inducible promoter. Upregulating SR1 and rocF promotes arginine and urea production, increasing exogenous CaCO₃ deposition. Over-producing YneA induces the filamentous cell phenotype, while SacB converts extracellular sucrose to levan glue.

To protect the environment our project will also include a design for a kill switch.