When you walk through a grocery store, you will undoubtedly come across the aisle with cleaning products plagued with “Anti-bacterial: Kill 99% of germs” across their labels. And that’s because all bacteria is bad, right? Well, not necessarily. Earlier this week we discussed the use of bacteria in a positive light- restoring and preserving art, and thus cultural heritage.
We spoke of a particular case in which bacteria, specifically a strain of Pseudomonas stutzeri, were used to destroy the impenetrable cross-links between a piece of cloth and glue that had entrapped a fresco. But what was perhaps more interesting to me, was the side-mentioned story of bacteria in restoring statues.
As we have traveled Italy, we have seen our fair share of statues and fountains all of which are subject to the unforgiving conditions of Mother Nature. When acid rain, or sulfuric acid, strikes the statue a reaction occurs transforming the calcium carbonate (insoluble) of the statue into calcium sulfate (soluble). This is a problem for two reasons: calcium from the statue is removed and unsightly black ‘crust’ is formed. Scientists have turned to two different bacterial strains to solve the problem, Bacillus cereus and Desulfovibrio vulgaris.
Calcium sulfate can crystallize and during this process airborne pollutants can be enclosed in the matrix. This is essentially what comprises the black ‘crust.’ Desulfovibrio vulgaris is a sulfate-reducing bacterium that is used to digest the calcium sulfate and remove the discoloring of the statues. On the other hand, Bacillus cereus is used to restore the calcium loss. These bacteria, which naturally produce calcium accumulations, are allowed to grow on the surface of the statue. Once the food supply runs out, the bacteria die and are removed, leaving behind a coating of calcium protecting the statue from further deterioration. These two strains work hand-in-hand; while one restores, the other preserves.
The case study just offers more proof of the degree to which art and science are intertwined and helps to challenge the “bad reputation” bacteria is known for.
For further reading: Jose Luis Ramirez, Maria A. Santana, Ivan Galindo-Castro, Alvaro Gonzalez, The role of biotechnology in art preservation, Trends in Biotechnology, Volume 23, Issue 12, December 2005, Pages 584-588 http://www.sciencedirect.com/science/article/B6TCW-4HCMS4Y-1/2/74a1aa67e35c05d6fe3b15d9089fa2e4
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