Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio - Coppito, I-67100, L'Aquila, Italy.
LBA-Laboratory of Biology of Algae, Department of Biology, University of Rome "Tor Vergata", Via Cracovia 1, I-00133, Rome, Italy; PhD program in Evolutionary Biology and Ecology, Dept. of Biology, University of Rome "Tor Vergata", Rome, Italy.
Sci Total Environ. 2023 Apr 20;870:161901. doi: 10.1016/j.scitotenv.2023.161901. Epub 2023 Feb 2.
An important field of research is devoted to the development of innovative, sustainable, and safe methodologies to counteract biodeterioration of stone monuments due to the growth of microbial communities. However, besides the biocide's efficacy, it is crucial to consider the features of substrates on which biocides must be applied, to define the so-called bioreceptivity of the lithic faces. In this research five different lithotypes, namely Lecce stone, Travertine, Peperino, Serena stone, and Granite, have been used as substrates for the growth of cyanobacterial biofilms. Open porosity, hygroscopic properties, and roughness parameters have been investigated for each lithotype and correlated to the photosynthetic yields of the biofilms colonizing the different stones to propose an easy method to estimate stone bioreceptivity. Different levels of coverage of the stone surfaces have been accomplished in relation to the typology of lithotypes. To develop innovative restoration methodologies against biodeterioration of stone monuments, a hydrogel-biocide system has been optimized by using a polysaccharide dispersion as a matrix where to embed T. vulgaris essential oil (at 0.25 % or 0.1 %) or its main component thymol (at 0.18 % or 0.07 %). The efficacy and the effect of the innovative biocide have been evaluated combining microscopy, photosynthetic measurements, and colorimetric analyses and both the biocides (with T. vulgaris EO or thymol) showed to be highly effective against the cyanobacterial biofilms for at least six months from the treatment without inducing any significant alteration to the lithic surfaces. The efficacy of thymol alone allows to treat colonized surfaces with a single active ingredient, or at least a mixture thereof, much cheaper and reproducible. The results obtained in this work pave the way to develop a sustainable cleaning protocol to counteract the biodeterioration of stone monuments or historic buildings induced by the presence of phototrophic biofilms that endangered their conservation.
一个重要的研究领域致力于开发创新的、可持续的和安全的方法，以对抗由于微生物群落生长而导致的石质纪念碑的生物降解。然而，除了杀生物剂的功效外，考虑到杀生物剂必须应用的基底的特征，定义所谓的石质表面的生物可接受性至关重要。在这项研究中，使用了五种不同的岩石类型，即莱切石、石灰华、佩佩里诺石、塞雷纳石和花岗岩，作为蓝藻生物膜生长的基底。研究了每种岩石类型的开放孔隙率、吸湿特性和粗糙度参数，并将其与在不同石头上定殖的生物膜的光合产量相关联，提出了一种估计石头生物可接受性的简单方法。根据岩石类型的不同，完成了不同程度的石头表面覆盖。为了开发针对石质纪念碑生物降解的创新修复方法，通过使用多糖分散体作为基质，优化了水凝胶-杀生物剂系统，在该基质中嵌入 T. vulgaris 精油（0.25%或 0.1%）或其主要成分百里酚（0.18%或 0.07%）。通过结合显微镜、光合作用测量和比色分析，评估了创新杀生物剂的功效和效果，两种杀生物剂（T. vulgaris EO 或百里酚）都显示出至少六个月内对蓝藻生物膜的高效性，而不会对石质表面造成任何显著的影响。单独使用百里酚可以用一种活性成分，或者至少是其混合物，来治疗已被生物膜污染的表面，成本更低，而且更具可重复性。这项工作的结果为开发可持续的清洁方案铺平了道路，以对抗由光合生物膜引起的石质纪念碑或历史建筑的生物降解，这些生物膜危及它们的保护。
