In Valencia, Spain, the Santos Juanes Church restoration is led by a mother-daughter team, Pilar Roig and Pilar Bosch, using bacteria to clean up stubborn glue from 18th-century frescoes. The microbiologist trains bacteria by feeding them samples of the glue which was made from animal collagen. The bacteria then naturally produce enzymes to degrade the glue. The family team then mixes the bacteria with a natural algae-based gel and spread it on the paintings, which were taken from the walls in the 1960s, then nailed back on, still covered in glue. After three hours, the gel is removed, revealing glue-free paintings. Bosch also applied her use of bacteria to restoration projects in Pisa and Monte Cassino in Italy and in Santiago de Compostela in northern Spain. She is now training up cohorts of a different kind of bacteria to clear walls of spray-painted graffiti.REUTERS VIDEO