A Medici family chapel created by Michelangelo that was cleaned with the help of bacteria has been presented to the public to mark the 545th anniversary of the Renaissance master’s birth.
Michelangelo was commissioned to sculpt the New Sacristy, in the Medici chapels in San Lorenzo church in Florence, in 1520.
Restorers struggled to clean the dirt and grime that accumulated over the centuries until resorting to an unconventional solution: bacteria.
The tomb is adorned with sculptures representing likenesses of two dukes from the powerful Medici family, Giuliano di Lorenzo and Lorenzo di Piero, plus four allegorical figures representing different times of the day, and the Madonna and Child.
A team spent eight years restoring the delicate monument, using a bacteria-infused gel during the final stage of the project to remove the most stubborn dirt marks.
Scientists tested 11 strains of bacteria on marble before it was decided that three non-toxic varieties – Serratia ficaria SH7, Pseudomonas stutzeri CONC11 and Rhodococcus sp. ZONT – would be the most effective for Michelangelo’s masterpiece. Serratia ficaria, a bacterium that causes urinary tract infections, managed to remove dirt from the tomb in two days.
Part of the sarcophagus was in a particularly bad state as the remains of Alessandro Medici, a ruler of Florence who was assassinated, had been buried in the tomb without being eviscerated, as was customary at the time for Medici family members. This meant that over time the organic liquids from the corpse had started to seep through and stain Michelangelo’s work.
The restoration was completed last year and the cleaned-up tomb was presented to the public in an event hosted by the Academy of the Arts of Drawing.
Monica Bietti, an art historian and former chief of the Medici chapels museum, who led the restoration project, said: “The restoration of one of the most symbolic places of art required knowledge, experience and science combined with the qualities of sensitivity and intelligence. For this reason, the work was tested from the start and then subjected to constant optical, methodological and scientific checks.”
