Murals meet microbes: at the crossroads of microbiology and cultural heritage.

Our cultural heritage consists of manifold cultural expressions and represents a defining feature of our societies that needs to be further inherited to future generations. Even though humankind always fought a daily struggle for survival, at the same time, it seemed to have a spiritual need that went far beyond mere materialistic satisfaction and nowadays manifests in sometimes very ancient, yet brilliant artistic works. This fundamental legacy is endangered by several instances, including biodeterioration. Indeed, microorganisms play a significant role in the decline of all forms of tangible cultural heritage, including movable, immovable and underwater cultural heritage. Microbial colonization, biofilm formation and damaging metabolite production eventually result in critical decay. Thus, efforts to mitigate the negative impact of damaging microorganisms have been pursued with diverse physical, chemical and biological approaches. Intriguingly, recent advances have unveiled that specific microorganisms and microbial-based technologies also have the potential for cultural heritage preservation and present unique advantages. This short piece provides a quick overview on the duality of microorganisms in the conservation and restoration of cultural heritage.