Send in the Bugs. The Michelangelos Need Cleaning.

Last fall, with the Medici Chapel in Florence operating on reduced hours because of Covid-19, scientists and restorers completed a secret experiment: They unleashed grime-eating bacteria on the artist's masterpiece marbles. From a report: As early as 1595, descriptions of stains and discoloration began to appear in accounts of a sarcophagus in the graceful chapel Michelangelo created as the final resting place of the Medicis. In the ensuing centuries, plasters used to incessantly copy the masterpieces he sculpted atop the tombs left discoloring residues. His ornate white walls dimmed. Nearly a decade of restorations removed most of the blemishes, but the grime on the tomb and other stubborn stains required special, and clandestine, attention. In the months leading up to Italy's Covid-19 epidemic and then in some of the darkest days of its second wave as the virus raged outside, restorers and scientists quietly unleashed microbes with good taste and an enormous appetite on the marbles, intentionally turning the chapel into a bacterial smorgasbord. "It was top secret," said Daniela Manna, one of the art restorers. On a recent morning, she reclined -- like Michelangelo's allegorical sculptures of Dusk and Dawn above her -- and reached into the shadowy nook between the chapel wall and the sarcophagus to point at a dirty black square, a remnant showing just how filthy the marble had become. She attributed the mess to one Medici in particular, Alessandro Medici, a ruler of Florence, whose assassinated corpse had apparently been buried in the tomb without being properly eviscerated. Over the centuries, he seeped into Michelangelo's marble, the chapel's experts said, creating deep stains, button-shaped deformations, and, more recently, providing a feast for the chapel's preferred cleaning product, a bacterium called Serratia ficaria SH7. "SH7 ate Alessandro," Monica Bietti, former director of the Medici Chapels Museum, said as she stood in front of the now gleaming tomb, surrounded by Michelangelos, dead Medicis, tourists and an all-woman team of scientists, restorers and historians. Her team used bacteria that fed on glue, oil and apparently Alessandro's phosphates as a bioweapon against centuries of stains.

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