Inspired by the human body, Jonkers, who works at the Delft University of Technology in the Netherlands, created self-healing concrete. He embeds the concrete with capsules of limestone-producing bacteria, either Bacillus pseudofirmus or Sporosarcina pasteurii, along with calcium lactate. When the concrete cracks, air and moisture trigger the bacteria to begin munching on the calcium lactate. They convert the calcium lactate to calcite, an ingredient in limestone, thus sealing off the cracks.  — smithsonianmag.com

Locating and patching cracks in old concrete is a time-consuming business, but rebuilding concrete structures is expensive. Jonkers thinks the solution is to fight nature with nature: he suggests combating water degradation by packing the concrete with bacteria that use water and calcium lactate "food" to make calcite, a natural cement. — newscientist.com