Microbes do plenty of amazing things. Now they restore medieval art. From Cultured Bacteria Save Medieval Italian Frescoes:
After a glue used in a bungled earlier restoration attempt clouded one of the 14th and 15th century paintings in the Camposanto cemetery fresco cycle in Pisa, scientists turned to a bacteria called Pseudomonas Stutzeri — with spectacular results.
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The 4,900-square-foot of frescoes in the “Conversion of Saint Efisio and Battle” by Spinello Aretino were nearly destroyed in a World War II air raid, and were further damaged by botched restoration efforts when the paintings were peeled off the walls and glued to canvases.Over the following years, the organic glue used hardened and clouded, wrecking paint pigments and resisting all efforts at removal. Attempts at using chemical solvents took their own toll on the frescoes.
But the revolutionary bacteria culture degraded 80 percent of the glue within just 10 hours, revealing the colorful garments of Aretino’s angels and of Saint Efisio himself.