Bacterial route to mother-of-pearl may provide shelter for lunar explorers

Mother-of-pearl is one of the most intriguing and intensely studied materials found in nature. Also known as nacre, it is a natural composite, consisting of layers of protein-and mineral-based substances. It is lightweight, immensely tough and stiff, providing an important component within the calcium carbonate-based protective shell of molluscs.

Materials scientists have been trying for over 30 years to produce synthetic nacre, but have only succeeded using expensive equipment, extreme temperatures, high pressures and often toxic chemicals.

"Many people creating artificial nacre use polymer layers that are only soluble in non-aqueous solutions, an organic solvent, and then they have this giant bucket of waste at the end of the procedure that has to be disposed of," explained Anne Meyer, a biologist at the University of Rochester in New York, who has led a team that has developed a biologically-based route to synthetic nacre that they believe may overcome previous problems.

The Rochester team’s method avoids harsh chemicals, instead being based around bacteria. Moreover, the starting material is urea: a nitrogen-containing compound found in urine and commonly used in fertilisers. In a paper in the journal Small, Meyer and the team explain how they use two strains of bacteria to replicate the layered structure of nacre.