A eficácia antifúngica do óleo essencial de Melaleuca alternifólia na mitigação dos danos causados pela microbiodeterioração do acervo de indumentárias e telas de pintura do Museu Histórico Abílio Barreto

Abstract

Fungi are among the biological agents that pose the greatest risks to the safeguarding of textile heritage. The general objective of this research is to test the antifungal efficacy of the essential oil (EO) of M. alternifolia against a fungus from the clothing and painting collection of the Abílio Barreto Historical Museum (MHAB) in the city of Belo Horizonte (MG). To achieve this objective, however, it was necessary to elect a representative from each type of collection to collect textile samples and isolate filamentous fungi. The microscopy examinations carried out allowed us to characterize the types of biodamage caused to fibers and fabrics by the colonization of microorganisms. Plating the textile samples on PDA medium (Potato Dextrose Agar) allowed the isolation of 30 filamentous fungi and grouping them into 13 morphotypes. The morphotypes were subjected to molecular identification by sequencing the internal transcribed spacer region (ITS) of the ribosomal RNA gene and, subsequently, to the identification of micromorphological structures. The taxa identified corresponded to the genera Penicillium, Aspergillus and Paecilomyces. An isolate of the Aspergillus species was selected to carry out tests to determine the Minimum Inhibitory Concentration (MIC), conidial germination in prototyped fabrics and painting canvases and EO vaporization in a micro atmosphere. The results obtained demonstrated that EO from M. alternifolia has fungistatic activity capable of inhibiting the growth of the Aspergillus sp isolate. in cotton, wool, linen and polyester fabrics and in industrialized cotton canvases at a MIC of 8 mg/mL. The tests also indicated that diluting the EO in hydrated ethyl alcohol 70% (v/v) at a concentration of 8% (v/v) to increase the oil's dispersion capacity in the environment does not compromise the integrity of the textile surface and the pictorial layer of the prototyped materials. More studies are, however, necessary to evaluate the effectiveness of EO against other isolated fungi. It is also important to evaluate the possible adverse effects of long-term application of the oil on textile materials and other clothing components, such as leather, gelatin, bones and metals.