A team of students in the UK has engineered bacteria that can knit together cracks in concrete structures by producing a special glue.
The genetically modified microbe Bacillus subtilis has been programmed to swim deep into fine cracks in concrete after being sprayed on the surface.
Images: Newcastle University
|Genetically engineered bacteria swim to the bottom of the crack and produce a glue with reinforcing fibers.|
At the bottom of the crack, the microbes produce a mixture of calcium carbonate and a bacterial glue that combines with the filamentous bacterial cells to “knit” the crack back together, report officials at Newcastle University, where the work has been underway for many months.
Preventing Structural Failure
Ultimately hardening to the same strength as the surrounding concrete, the so-called “BacillaFilla” can prolong the life of structures and may help prevent catastrophic structural failures, university officials said.
The students took a gold medal for their research last year in the International Genetically Engineered Machines contest (iGEM), which drew 130 student teams from around the world to the Massachusetts Institute of Technology (MIT) in Boston.
|The nine Newcastle University students who developed BacillaFilla earned a gold medal in an international competition for their research.|
The discovery could help reduce the environmental toll of concrete production and help restore the structural integrity of cracked concrete.
“Around five percent of all man-made carbon dioxide emissions are from the production of concrete, making it a significant contributor to global warming,” said Dr. Jennifer Hallinan, a director of the project.
“Finding a way of prolonging the lifespan of existing structures means we could reduce this environmental impact and work towards a more sustainable solution.
“This 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.”
Germination on Contact
The BacillaFilla spores start germinating only when they make contact with concrete— triggered by the very specific pH of the material—and have a built-in “self-destruct” gene that makes them unable to survive in the environment, the university says.
|A graphic shows the course of BacillaFilla in crack repair.|
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 that produce calcium carbonate crystals;
• Cells that become filamentous, acting as reinforcing fibers; and
• Cells that produce a Levans glue which acts as a binding agent and fills the gap.
The nine students’ backgrounds include computer science, civil engineering, bioinformatics, microbiology and biochemistry.
Professor Neil Wipat called the students’ work “a great achievement” that has become the basis of additional research at the university.