The Cappelle medicee are two extensions of the Basilica of San Lorenzo in Florence, Italy, built in the 16th-17th centuries.
The Sagrestia Nuova was designed by Michelangelo. In the new sacristy collection room, he designed four sculptures for the tombs of members of the Medici family, named after four periods of the day: "Morning", "Twilight", "Day" and "Night".
▲Sculpture of the Medici Chapel-"Day", picture from: DeAgostini
Now that hundreds of years have passed, the surface of these sculptures has long been stained and discolored, and the gorgeous white walls have also dimmed. Although repairers have removed most of the flaws in the past ten years of restoration, they have nothing to do with those stubborn stains.
After research, these stains seem to be related to Alessandro de' Medici, the former ruler of Florence. His body was placed in the sarcophagus in the Medici Chapel, but it was not adequately treated before being buried, which resulted in difficult-to-remove stains.
▲Picture from: New York Times
In November 2019, the Medici Chapel Museum invited the National Research Council of Italy. They discovered through infrared spectroscopy that these sculptures and the calcite, silicate and other organic residues on the two tombs were made up of these substances. Remove those difficult-to-remove stains.
They decided to try to "eat" them with bacteria.
Anna Rosa Sprocati, a biologist at the National Agency for New Technology in Italy, chose a few of the most suitable strains from nearly 1,000 strains, but they are usually used to break down petroleum or heavy metals. Some bugs in her laboratory liked phosphate and protein, but Carrara marble that Michelangelo liked was also their delicacy.
So Monica Bietti didn't choose them in the end.
▲Monica Bietti, the former curator of the Medici Chapel Museum, picture from: The New York Times
Last fall, due to the impact of the epidemic, the business hours of the Medici Chapel were greatly reduced. She decided to take this opportunity to teach these stubborn stains a lesson.
The former curator of the Medici Chapel Museum organized a small team of scientists, historians, and restoration experts to try to find the most suitable strain for the statue.
They tested the strains behind the altar, and she said that the selected bacteria were harmless and had no spores.
▲Betty’s team is testing strains, the picture comes from: The New York Times
In the end, the team chose Pseudomonas stutzeri CONC11, which is a pale yellow, irregular-edged bacteria that they separated from the waste of a tannery near Naples.
For different stains, they also use different bacteria.
They used Rhodococcus to remove mold residues, glue, and oil from the ears, and used xanthan gum derived from Xanthomonas rape to clean the face of the statue "Night". The head of Duke Giuliano above the grave is also Received similar treatment.
For Alessandro who caused this disaster, they used a bacteria called Serratia ficaria SH7 as a "cleaning product."
SH7 ate Alessandro.
▲The restored statue, the picture comes from: The New York Times
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