Prospecting for populations of filamentous fungi in a Brazilian oil painting and susceptibility to natural antifungals

The preservation of contemporary artwork is a growing problem in conservation due to their susceptibility to biodeterioration. Fungal colonization regularly targets these cultural assets, which can have great artistic and historical significance. Filamentous fungi implicated in the deterioration of oil paintings have a strong enzymatic degradation capacity, targeting components, such as vegetable oils and resin. This process is enhanced by interactions with pigments and chemicals, which can act as nutrient sources for fungi. Traditional antifungal treatments have been extensively explored as a technique to counteract biodeterioration; however, their efficiency is frequently restricted by their toxicity to conservators, environmental impact, and the ability to create chemical changes in the materials of the artworks. Natural antifungal compounds, specifically essential oils (EOs) extracted from <i>Melaleuca alternifolia, Curcuma longa</i>, and <i>Thymus vulgaris</i> were assessed for their antifungal efficacy against metabolically active fungal isolates. Furthermore, <i>in vitro</i> assays demonstrated that the interaction between these fungal strains and the tested EOs resulted in significant growth inhibition, indicating their potential as effective antifungal agents, and all EOs tested showed low minimum inhibitory concentration (MIC) values for <i>Penicillium crustosum</i> and <i>Aspergillus flavus</i>. On the other hand, <i>Pythium graminicola</i> and <i>Diaporthe longicolla</i> showed higher MIC values for all EOs tested. Fungal identification was conducted through the examination of both macroscopic and microscopic morphological characteristics as well as the Internal Transcribed Spacer (ITS) region of the rDNA. This study highlights the efficacy of three essential oils as a sustainable alternative to conventional antifungal agents, which are often associated with toxicity in artwork preservation.