Superglue in the seabed

The strongest glue so far found in nature could have applications in engineering and medicine, according to its discoverers. Secreted by a marine microorganism, the glue sticks more than twice as hard as the strongest ‘superglue’ currently available.

Yves Brun, a bacteriologist from Indiana University in Illinois, has been working with physicists and engineers from Indiana and Brown University in Rhode Island to study the bacterium Caulobacter crescentus. One of the first species to colonise surfaces submerged in rivers and streams, Caulobacter secretes a sticky compound through a stalk-like structure at its base called a holdfast. These compounds, which are composed of chains of sugar molecules, allow it to hold fast to the inside of metal pipes.

To assess the strength of the glue, the team allowed Caulobacter to colonise the surface of a thin glass pipette, then used a micromanipulator to pull the bacteria off the surface. In 14 trials, the bacteria needed a force of 0.11 to 2.26µN per cell to detach them from the glass surface. Scaling up, this represents a stress of 70N/mm2, compared with breaking stresses of 18-28N/mm2 for commercial cyanoacrylate-based superglues.