In 2017, Caselli and her team worked with the church to swab the painting so they could culture surface bacteria, and remove small samples (less than 4 millimeters squared) for chemical analysis. Both the front and back of the painting were covered in microbes, but the location of each class of miniature colonizer varied by pigment. Bononi appears to have derived his red and brown paints from soil rich in iron oxide. There, researchers found high concentrations of environmental yeasts and molds. Where Bononi painted with lighter colors like yellow, derived from lead tin, and pink, from a mixture of earth and lead white, Cladosporium spores were thriving. Alternaria, meanwhile, was found only where the painting touched the ground.