Bacteria as restorers of works of art: future allies of heritage conservation?

An Italian team detailed the deterioration of a 17th-century Baroque painting caused by bacteria and fungi. They also identified three bacterial species that have the ability to counter such deterioration.

 

When it comes to art, biodegradability is rarely compatible with durability. The deterioration of works of art and buildings by microorganisms is a threat dreaded by curators of historic pieces and sites worldwide. In the Santa Maria in Vado church in Ferrara, Italy, the 1620 painting “Incoronazione della Vergine”* by the Italian artist Carlo Bononi, has suffered the ravages of time, natural disasters (2012 earthquake)… and microbes.

The perfect cocktail

Researchers from Ferrara made their contribution to the restoration of this work of art by analyzing the microbial life that had grown on the painting. By extracting samples from the painting–which was originally displayed on the ceiling and is now standing on the floor in a niche–the Italian team was able to observe two types of bacteria: Staphylococcus on the front, the most eroded section, and Bacillus on the back. This typical 17th-century painting is covered with natural pigments, which these bacteria love to feast on, especially red lac, red earth and yellow earth. Associated with ideal temperature, humidity and light conditions, it was the perfect cocktail to promote the growth of these “paint-eating” bacteria.

Each area has its own fungi

High heat and humidity also attract fungi: the scientists found in other darker areas Aspergillus and Penicillium molds. These two species are also found in museums and libraries housing old paintings and paper-based items. Lighter areas (yellowish light blue or pink), however, hosted Cladosporium spp., while the part resting on the floor was stained by Alternaria yeast.

Fighting fire with fire: rescuer bacteria

Identifying aggressors is one thing, finding saviors is another, although much more useful. The same Italian team was successful in their quest: they discovered that three species of Bacillus could prevent growth and harmful effects of microorganisms attracted to colors. These bacteria could become allies in the restoration of paintings and works of art subject to microbial attacks. We now have to make sure that they do not affect the paintings in any way. (Art)work in progress

 

* The Coronation of the Virgin

 

Sources:

E caselli et al, Characterization of biodegradation in a 17th century easel painting and potential for a biological approach, PLoS One. 2018 Dec 5;13(12):e0207630