Influence of biofilm on the alteration of Mn- and Fe-bearing glasses in long-term dynamic experiments

This is the authors' abstract. We don't add key points for this paper.

Stained-glass windows are vulnerable to environmental and microbial degradation. This study focused on a dynamic experimental protocol to examine biofilm influence on Manganese (Mn) and/or Iron (Fe)-bearing model stained glass. A model bacterial strain ( Pseudomonas putida) and a mixed bacterial consortium collected on Notre-Dame Cathedral (Paris, France) windows were cultivated in the presence of glass. The continuous medium renewal within the bioreactors promoted thick and adherent biofilm formation. Phosphorus from the glass was shown to be the key nutrient to promote bacterial growth. The composition of the glasses significantly influenced the development of biofilms, particularly iron, shown to limit biofilm formation: in the experiments involving P. putida , one order of magnitude was observed between the thickness of the measured dry biofilm on the Fe-free glass versus the Fe-bearing glass. However, the influence of iron on the taxonomic profiles of the population sampled on Notre-Dame de Paris was not significant. A clear correlation was shown between biofilms and the thicknesses of the Si-rich layers formed on the glass surface, evidencing the dominant role of biofilm/glass interfaces over bulk chemistry. Finally, biofilms formed by P. putida led to the formation of manganese oxides, reproducing the browning pathology, a not well-understood phenomenon observed on ancient Mn-bearing glasses.