Scientists survey the microbes eating a 17th century painting

Dec. 6 (UPI) -- When researchers in Italy took a closer look at the canvas of a 17th century painting, they found an array of microorganisms.

Of course, scientists knew they'd find microbes. Bacteria and other microorganisms occupy almost every surface on Earth, but they couldn't be certain which species and strains colonize ancient artwork.

While some bacterial strains are well suited for the consumption of oil and pigments, others can help contain the growth of their more harmful relatives. The results of their survey -- published this week in the journal PLOS One -- could help preservationists identify the most harmful and helpful microbes.

For their survey, researchers chose "Incoronazione della Virgine," a work by the Italian painter Carlo Bononi, completed in 1620. A portion of the painted canvas has been damaged by art-eating microbes.

To get a better sense of the tiny vandals, scientists snipped a tiny piece of the canvas and took it to the lab for analysis. Researchers used both microscopy and microbial culture techniques to identify the microorganisms present on the sample.

The survey revealed the presence of Staphylococcus and Bacillus bacterial strains. Scientists also found filamentous fungi belonging to several genera, including Aspergillus, Penicillium, Cladosporium and Alternaria.

It's likely some of the pigments used in the oil paints, including red lac and red and yellow earths, provide nutrients for the colonizing microbes.

After surveying the microbial population, researchers tested a biocompound featuring spores from three three Bacillus bacteria strains. The application curtailed the growth of several of the bacterial and fungal strains.

The study's results suggest preservationists can deploy biocompounds to limit the harm of ancient microbes, without the risk of accelerating biodegradation.

"Clarification of biodeterioration processes in artworks is important, as it could help in preventing or solving the associated damages," researchers wrote in their paper. "This study investigated such aspects in a 17th century painting, by analyzing both microbial communities and chemical composition of painting, also evaluating a possible biological way to counteract these phenomena."