Functional characterization of microbial communities involved in Lascaux Cave black stain wall alterations

Paleolithic art caves attract a million-tourist per year, causing harsh imbalance of cave microbiota promoting the development of specific microbial taxa that might be responsible of stains apparition on cave walls. Because of strong anthropization, chemical products such as benzalkonium chloride (BAC) have previously been applied on cave walls to prevent rock alterations, conducing to the development of black stains. Taxonomic studies showed that pigmented microorganisms were selected in black stains rock alteration, while Pseudomonas genus were counter-selected, but their functional characterization remains unclear. Lascaux Cave provided an ideal ecosystem to investigate the relation between BAC degradation and pigment biosynthesis in black stains occurring in black stains threatening cultural heritage.