Phytochemical Compounds as Cleaning Agents on Granite Colonized by Phototrophic Subaerial Biofilms

Abstract

The society has become increasingly interested in using natural products over chemicals for cleaning activities. In this study, the cleaning potential of formulations embedded in a hydrogel matrix and composed respectively of essential oils (EOs) of Origanum vulgare, Thymus vulgaris, and Calamintha nepeta, and their respective main active components (EO-ACs), viz., Carvacrol, Thymol, and Pulegone, on a phototropic biofilm growing on granite was investigated. In addition, and for comparative purposes, analysis with the combination of the three EOs, the combination of the three EO-ACs, and Preventol RI-80® (one of the most effective commercial cleaning agents based on quaternary ammonium salts) in all three cases embedded in a hydrogel matrix, as well as only the hydrogel matrix, distilled water, and Preventol RI-80®, in both latter cases applied with brush, were also studied. The cleaning effect of the treatments was assessed immediately after the treatment and after one and two weeks by color spectrophotometry, a reliable tool to evaluate the presence and vitality of the phototrophs and the cleaning effectiveness in granite. C. nepeta and its active component Pulegone proved to be the most effective and yielded similar results, comparable to those of uncolonized granite, and better than those obtained with Preventol RI-80® applied with brush (most common way), especially at the end of the experiment. These promising first results support the suitable use of the phytochemical compounds used on phototrophs field where there are still few published studies and encourage further investigation toward the evaluation of their exhibited biocidal activity.

Single-Sided Portable NMR Investigation to Assess and Monitor Cleaning Action of PVA-Borax Hydrogel in Travertine and Lecce Stone

“…The success of these products is attributable to some of their intrinsic characteristics, in particular, (i) the atoxicity in their chemical composition and their being harmless towards the environment and human beings; (ii) their ability to incorporate organic solvents; and (iii) the ease of their application and removal procedures [ 29 , 38 , 39 ]. However, in the literature, there are only few papers investigating the effectiveness of PVA-hydrogels for cleaning rocks [ 5 , 40 , 41 , 42 , 43 ]. Recently, Riedo et al [ 44 ] tested the effectiveness of PVA-borax hydrogel in generic limestone samples treated with Paraloid B72 and cleaned using a 4-min gel application time.…”

Effect of Inorganic Carbon Concentration on the Development of Subaerial Phototrophic Biofilms on Granite

“…These results may; therefore, involve negative impacts regarding the possible effects of an increase in atmospheric CO 2 on the stone colonization and biodeterioration processes. An increase in growth of cyanobacterial biofilms and in pigment concentrations may exacerbate the aesthetic impact of these biofilms on stone-made cultural heritage and; therefore, lead to treatments being necessary (e.g., biocide coating [42], laser cleaning [43] or application of natural oils [44]) and/or loss of value. An essential strategy to prevent colonization and subsequent biodeterioration is the selection of appropriate materials for building, ornamental purposes or replacement.…”

New protective coatings against lampenflora growing in the Pommery Champagne cellar

“…The efficiency of Preventol RI80 was proven in many studies as a curative treatment to eliminate a wide spectrum of microorganisms, such as fungi and bacteria (Blazquez et al, 2000;Maxim et al, 2012). It was also proven to be efficient against photosynthetic microorganisms such as algae, cyanobacteria, lichen (Ascaso et al, 2002;Vannini et al, 2018;Genova et al, 2020), complex biofilms on outdoor monuments (Coutinho et al, 2016;Sanmartín et al, 2020) and in subterranean environments (Nugari et al, 2009;Urzì et al, 2016). For our study, biocides were applied on non-colonised stone samples, as preventive treatments to avoid the settlement of the lampenflora microorganisms.…”