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.

FLORENCE — 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.