# Controlling Lampenflora in Heritage Sites: In Situ Testing of Polyoxometalate–Ionic Liquids in the Pommery Champagne Cellar

## TL;DR

This study tests new biocidal materials to protect a historic Champagne cellar from harmful microbial growth caused by artificial lighting.

## Contribution

POM-ILs are shown to be a sustainable and effective alternative to traditional biocides for preserving cultural heritage.

## Key findings

- POM-ILs effectively inhibited microbial growth for one year with lower concentrations than Preventol RI80.
- Metagenomic analysis showed reduced microbial diversity in POM-IL-treated areas.
- POM-ILs had better long-term inhibition of photosynthetic organisms compared to Preventol RI80.

## Abstract

Artificial lighting, essential for geotouristic purposes in subterranean sites, has facilitated the growth of colored photosynthetic organisms (lampenflora) on monumental 19th century bas‐reliefs of the Pommery Champagne cellar—a UNESCO‐protected heritage site—causing significant aesthetic and physical deterioration. To sustainably preserve these stone artworks, biocidal polyoxometalate–ionic liquids (POM‐ILs) are tested alongside the commercial biocide Preventol RI80 on three trial zones: cleaned and colonized areas of a wall and clean stone samples positioned on a testing station within the cellar. After 1 year, untreated control areas exhibit growth/regrowth of biofilms, whereas surfaces treated with POM‐ILs or Preventol RI80 remain biofilm free. Measurements of colorimetry and chlorophyll fluorescence confirm the effectiveness of both biocides in controlling photosynthetic micro‐organisms. However, confocal fluorescence microscopy highlights a reduced long‐term inhibition by Preventol RI80 compared to POM‐ILs, despite the latter being applied at lower concentrations. Metagenomic analysis further validates the performance of POM‐ILs, showing a notable decrease in microbial richness and diversity in treated areas. While both products effectively inhibit phototrophs and fungi, their efficacy against Pseudomonadota is limited, likely due to microbial adaptation via antibiotic resistance genes. This study underscores the potential of POM‐ILs as a sustainable alternative for preserving cultural heritage against microbial colonization.

The article evaluates polyoxometalate–ionic liquids (POM–ILs) as biocidal agents against lampenflora in the UNESCO‐listed Pommery Champagne cellar. POM–ILs effectively inhibit microbial colonization over one year with minimal visual impact and outperform the commercial biocide Preventol RI80. Metagenomics and microscopy confirm POM–ILs’ long‐term efficacy, suggesting their sustainable potential in cultural heritage preservation.© 2025 WILEY‐VCH GmbH