Role of microorganisms in mural paintings decay

Abstract

The action of microbial communities on mural paintings, particularly in mortars and in pictorial layers, triggered numerous studies to identify the main biodeteriogenic agents and to better understand the role of microorganisms in the biodeterioration/biodegradation of these artworks. The biodegradation phenomenon is an important issue for the conservation of cultural heritage that needs urgent answers to their rehabilitation. Microbial activity and their ability to obtain elements by biosolubilization of the materials, essentials for their metabolism, can play an important role in the mural paintings deterioration, being fungi and bacteria the main biodeteriogenic agents responsible for aesthetic and structural damages. Thereby, to understand the causes of mural paintings deterioration, it is necessary to know the Microsamples were collected and asset of microanalysis techniques (scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX), µ-Raman spectroscopy, FTIR-ATR and microbiological/molecular techniques) were complementary used to correlate the chemical alterations with possible biological involvement. In this study we will be focus on the contribution of microbial communities to the formation of oxalates, lead white/red pigment oxidation and carotenoids formation that noticeably contribute to biodeterioration of mortars/mural paintings. These damages attributed to metabolic activity of microorganisms, promote polychromy degradation in specific pigments, efflorescence’s appearance, biofilms covering some areas of the painting, culminating in some cases in structural damage affecting mortars integrity.