High variability of microbial diversity from lampenflora of two bas-reliefs in the Pommery Champagne cellar

Pommery Champagne cellar has the originality to be in the underground of Reims city (NE-France) and has got monumental bas-reliefs carved in chalk walls. Bas-reliefs were illuminated for tourist visits and led to a lampenflora growth with different coloured areas which mar the beauty of the artworks. This study was focused on the characterization of the lampenflora of two bas-reliefs (named Fete de Bacchus and Silene) with the hypothesis that the different visual aspects of biofilms are associated to different phototrophic components. The goal was to control the proliferation of the lampenflora. Molecular analysis revealed distinct exogenous and opportunistic microorganisms in the two bas-reliefs though the bacteria : fungi ratio was remarkably constant. Pseudomonadota, Acidobacteriota, Bacteroidota and Actinomycetota were surprisingly dominant on Cyanobacteria. Bacchus had a higher microbial diversity than Silene. The different areas within Bacchus were composed of distinct communities while this was not the case for Silene. Phototrophs reflected specificity of each pit, Bacchus was mainly colonised by Chromochloris algae whereas Embryophyta and Stichococcus rather grew in Silene. The perspectives of this study are to propose a sustainable management of the cellar, notably the lighting strategy and visitor circuit, as well as preventive and curative treatments.