Just when Italian art restores were at a loss to save one of the world’s largest collections of 14th- and 15th-century medieval frescoes (paintings done on plaster) decorating a cemetery in Pisa near the Learning Tower., soil bacteria called Pseudomonas stutzeri came to the rescue. Restores were trying to clean the frescoes of paint-clouding grime contained within glue that had been used to repair them after damage in World War II. Traditional chemical reagents only further damaged the painting. Knowing that P. stutzeri could degrade nitrogen, plastic resins, and pollutants such as tetrachloroethylene, scientists cultured a strain of these microbes in the lab and applied them to the frescoes. Within 6 to 12 hours, the bacteria had cleaned approximately 80% of the glue residue and the remaining residue was removed with a light washing. The next proposed project for these microorganisms is removing black crust from limestone and marble monuments in Greece.