Send in the Bugs. The Michelangelos Need Cleaning.

In 1595, reports of deterioration and stains appeared on a sarcophagus within the elegant church Michelangelo designed for the Medicis’ burial. Plasters used to constantly reproduce the marvels he sculpted atop the tombs produced discolouring residues that have persisted for generations. The light in his elaborate white home faded.

Even after over a decade of renovations, some stains, like the filth on the tomb, persisted despite all efforts.

Send in the Bugs. The Michelangelos Need Cleaning.

Send in the Bugs. The Michelangelos Need Cleaning.

Italian restorers and scientists turned the chapel into a bacterial feast by secretly releasing microorganisms with good taste and an enormous appetite on the marbles in the months leading up to the outbreak of the Covid-19 virus.

Restoring artwork was a “top secret” operation, as art conservator Daniela Manna explained.

She reclined recently, like Michelangelo’s allegorical sculptures of Dusk and Dawn above her, and pointed to a smudged black square in the corner of the chapel where the wall meets the sarcophagus.

She speculated that the mess was caused by the assassinated body of Alessandro Medici, the ruler of Florence, which had been improperly interred in the tomb.

In the opinion of the chapel’s experts, he seeped into Michelangelo’s marble over the years, leaving behind deep stains and deformations in the shape of buttons, and more recently, providing a feast for the bacteria known as Serratia ficaria SH7, which is used as the chapel’s preferred cleaning product.

Former Medici Chapels Museum director Monica Bietti, surrounded by Michelangelos, dead Medicis, visitors, and an all-female team of scientists, restorers, and historians, said, “SH7 ate Alessandro.”

Her group utilised a bioweapon consisting of bacteria that fed on glue, oil, and allegedly Alessandro’s phosphates to combat stains that had been there for ages.

The museum had the Italian National Research Council examine the statues and two graves across the New Sacristy with infrared spectroscopy in November 2019; the results showed traces of calcite, silicate, and other, more organic, materials.

Anna Rosa Sprocati, a biologist at the Italian National Agency for New Technologies, used that as a guide to choose the best bacteria out of a library of over 1,000 strains, often used to degrade petroleum in oil spills or to lessen the toxicity of heavy metals. There were bugs in her lab that not only feasted on phosphates and proteins, but also on the Carrara marble that Michelangelo favoured.

We didn’t Choose those, Bietti Admitted.

The eight most promising strains were then examined by the restoration team behind the altar, using a miniature marble bingo board-style palette with rows of squares. The ones chosen, she assured me, were completely safe and spore-free.

After emerging from under the sarcophagus, Manna remarked, “It’s healthier for our health.” “In the sake of conservation and the preservation of art.”

The First Place the Bacteria was Planted

According to Sprocati, the tomb that Michelangelo designed for Giuliano di Lorenzo, Duke of Nemours, was the first place the bacteria was planted. There are allegorical sculptures of Day and Night adorning that sarcophagus; Day is a massive, contorted male figure, while Night is a woman whose body Michelangelo polished till she glowed in the moonlight.

The crew used Pseudomonas stutzeri CONC11, a strain of bacteria obtained from tannery waste near Naples, to wash her hair, and Rhodococcus sp. ZCONT, a species of bacteria isolated from diesel-contaminated soil in Caserta, to clean the residue of casting moulds, glue, and oil from her ears.

Achieving the desired results, it could be said. Paola D’Agostino, director of the Bargello Museums, which is in charge of the chapels and will formally unveil the project’s results in June, decided to err on the side of caution with Night’s face. Bietti did as well, and so did Pietro Zander, a Vatican specialist who tagged along.

They gave the restorers permission to use micro-gel packs containing xanthan gum on her face; this stabiliser is derived from the Xanthomonas campestris bacteria and is commonly found in toothpaste and cosmetics.


A similar effect was achieved with the head of Duke Giuliano, which was placed above his tomb.

And then in February of 2020, Covid struck, forcing the museum to close in March and halting the entire construction endeavour.

Sprocati didn’t want to deal with the bugs, so she went elsewhere. Using bacteria taken from a Naples industrial site, her team of scientists removed centuries’ worth of votive candle wax from Alessandro Algardi’s baroque masterwork, the Meeting of Attila and Pope Leo, a huge marble relief in Rome’s St. Peter’s Basilica.