Bacteria repairs concrete

Students at Newcastle University have genetically engineered a bacteria called Bacillus Subtilis to enable it to repair cracks in concrete which can cause catastrophic structural failure.

The genetically-modified bacteria has been programmed to swim down fine cracks in the concrete. Once at the bottom, it would produces a mixture of calcium carbonate and a bacterial glue which would combine with the filamentous bacterial cells, effectively ’knitting’ a building back together.

Ultimately hardening to the same strength as the surrounding concrete, the ’BacillaFilla’ – as it is named – has been developed to prolong the life of structures which are environmentally costly to build.

The students’ instructor Dr Jennifer Hallinan said that the bacteria could be particularly useful in earthquake zones where hundreds of buildings have to be flattened because there is currently no easy way of repairing the cracks and making them structurally sound.

The BacillaFilla spores only start germinating when they make contact with concrete – triggered by the very specific pH of the material – and they have an in-built self-destruct gene which means they would be unable to survive in the environment.

Once the cells have germinated, they swarm down the fine cracks in the concrete and are able to sense when they reach the bottom because of the clumping of the bacteria.

This clumping activates concrete repair, with the cells differentiating into three types: cells which produce calcium carbonate crystals, cells which become filamentous acting as reinforcing fibres and cells which produce a Levans glue which acts as a binding agent and fills the gap.

The nine students, whose backgrounds range from computer science, civil engineering and bioinformatics to microbiology and biochemistry, recently presented their idea at the International Genetically Engineered Machines contest (iGEM).