Plant extracts to control microbial growth: a “green” potential strategy

growth process and vegetative development have a direct consequence on the conservation of cultural assets. Recently, due to the use of many chemical compounds applied in biodeteriogens growth control, the attention has been focused on the risks resulting from these treatments that may affect human health (operators, visitors) and the environment. In order to develop alternative methods to traditional biocides, several studies have been focused to various natural products with potential antimicrobial activity, particularly against fungi and bacteria associated with the biodeterioration of cultural assets (Borrego et al., 2012; Sakr et al., 2012; Guiamet et al., 2008). In this study, antimicrobial activity of three different plant products, Tea tree oil (essential oil), Nepeta nepetella L. and Allium sativum L. extracts has been evaluated against bacteria and fungi, previously isolated from colonized manufacts and identified by microscopy and molecular biology investigations (Palla, 2012), using three different in vitro antimicrobial assays in order to develop the most appropriate method: micro- dilution in microtiter plates, well-plates diffusion and Agar-diffusion disk method (Stupar et al., 2014; Ghalem and Mohamed, 2008). Bioassays show a different susceptibility to the tested plant extracts, establishing for each bacteria and fungi the Minimum Inhibitory Concentration (MIC) and defining the diameter of the growth inhibition area. Among these three methods, the most simple and quick has been Agar- diffusion disk method, based on the methodology used by Kirby-Bauer. Therefore, this result supports the data reported in literature and shows an important potential implication for the possible use in the control of biodeterioration of cultural heritage, respecting of the human health and the environment (Sasso et al., 2013; Guiamet et al., 2008).