Microbes Rescue Art
Much of the world’s great outdoor art, especially marble statuary, is dissolving away through acid rain. And some microbes help it along by making acids.
But certain microbes actually consume the acids that deposit on the statues. Micro4Art is a new “product” composed of sulfate-reducing bacteria. The bacteria use sulfate (part of sulfuric acid) as an oxidant which they “breathe” instead of oxygen. They use the oxidant to respire on lactate (weak-acid product of sugar), a process yielding energy for the bacteria. So if you apply the bacteria plus lactate onto the black crusted statue, they will take the electrons and hydrogens from lactate, and combine them with sulfate to form water and hydrogen sulfide. These products evaporate or wash away.
Another story shows dramatic results in a Florentine cemetery, where sculptures of draped skulls were restored. The bacteria used are Desulfovibrio vulgaris; a microbe with a poor reputation from aquatic environments where they corrode metal, and from causing possible imbalance in the intestines of autistic children. But used in the right place, these bacteria may salvage many historical artworks.