‘BacillaFilla’, bacteria that can knit cracks in concrete
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 surfaces.
BacillaFilla would swim deep into the cracks. Repair would be effected by production of CaCO3, filamentous B. subtilis cells and levansucrose glue. CaCO3 expands at the same rate as concrete, making it an ideal filler. Filamentous B. subtilis cells have similar tensile strength to the synthetic fibres used in fibre-reinforced concrete, and provide reinforcement. Levansucrose glues CaCO3 and filamentous cells in place.
B. subtilis 168 sporulates, making it ideal for storage and transportation. The cells can be made to be tolerant to concrete’s high pH.
We designed a swarming BioBrick part for repairing B. subtilis 168′s defective swrA and sfp genes, 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 also includes a design for a kill switch.