Biodeterioração do patrimônio cultural e aplicação de técnicas não destrutivas de monitoramento e controle de populações microbianas

Abstract

Conservative restaurators face problems for the preservation of works and documentary collections due to damage caused by microorganisms. Water, oxygen, gases, acids, temperature and light are aggressive agents that induce structural changes in addition to the physicochemical factors themselves that can interfere with biodeterioration. Microbiological inspection in selected areas of the work to be restored and the environment in which it is inserted is fundamental in the study of biodeterioration, control and detection of microorganisms present. This study was carried out in the Imperial Throne of D. Pedro II and a work of Candido Portinari. Fungi are the biological agents most active because they penetrate cellulosic fibers and result in material loss due to acid corrosion, enzymatic degradation and mechanical attack. Against biodeterioration, gamma radiation has been shown to be a safe and effective technique, widely used with high efficiency in reducing microbial load. The study of gamma radiation for decontamination was carried out in isolated colonies from Portinari's work, in order to enable an appropriate treatment of the same in order to use the knowledge acquired in works of art with equivalent characteristics. One of the objectives of the work was, from the irradiation of the colonies, to evaluate the efficacy of the ionizing radiation technique for its non-destructive treatment. For this purpose, procedures were performed to collect the samples, culture and isolation of fungi, classical identification and molecular biology, irradiation of samples with Cesium 137 and peak of irradiated fungi for viability analysis. The radiation doses used, 16, 19 and 22 kGy, were stipulated based on previous studies that showed resistance of some fungal species to gamma radiation. Of the various fungi isolated, Penicillium and Cladosporium predominated. The fungi Penicillium, Cladosporium, Nigrospora and Curvularia showed resistance to the dose of 16 kGy and the genus Cladosporium only presented lethality at the dose of 22 kGy. Paper documents containing iron-gall inks are also the target of biodeterioration and degradation. The use of non-destructive techniques in the analysis of documents in order to help identify degradation and develop more appropriate restoration techniques are relevant because it is unceasing to search for procedures that respect the ethical criteria of minimal intervention. The use of X-ray fluorescence (XRF) can be used in the identification and analysis of chemical species present in iron-gall inks which are responsible for the acceleration of the processes of chemical degradation of cellulose and biodeterioration processes. The use of accelerated aging technology assists in the simulation of the aging conditions of paper that undergoes degradation by hydrolysis mechanisms and oxidation of cellulose in the presence and absence of iron-gall inks.