de Los Ríos Asunción, Cámara Beatriz, García Del Cura M A Angeles, Rico Víctor J, Galván Virginia, Ascaso Carmen
Instituto de Recursos Naturales, Centro de Ciencias Medioambientales (CSIC), Serrano 115 dpdo., 28006 Madrid, Spain.
Sci Total Environ. 2009 Jan 15;407(3):1123-34. doi: 10.1016/j.scitotenv.2008.09.042. Epub 2008 Oct 30.
In this study, the deterioration effects of lichens and other lithobionts in a temperate mesothermal climate were explored. We examined samples of dolostone and limestone rocks with visible signs of biodeterioration taken from the exterior wall surfaces of four Romanesque churches in Segovia (Spain): San Lorenzo, San Martín, San Millán and La Vera Cruz. Biofilms developing on the lithic substrate were analyzed by scanning electron microscopy. The most common lichen species found in the samples were recorded. Fungal cultures were then obtained from these carbonate rocks and characterized by sequencing Internal Transcribed Spacers (ITS). Through scanning electron microscopy in back-scattered electron mode, fungi (lichenized and non-lichenized) were observed as the most frequent microorganisms occurring at sites showing signs of biodeterioration. The colonization process was especially conditioned by the porosity characteristics of the stone used in these buildings. While in dolostones, microorganisms mainly occupied spaces comprising the rock's intercrystalline porosity, in bioclastic dolomitized limestones, fungal colonization seemed to be more associated with moldic porosity. Microbial biofilms make close contact with the substrate, and thus probably cause significant deterioration of the underlying materials. We describe the different processes of stone alteration induced by fungal colonization and discuss the implications of these processes for the design of treatments to prevent biodeterioration.
在本研究中，我们探讨了温带中温气候下地衣和其他石生生物的劣化作用。我们检查了取自西班牙塞哥维亚四座罗马式教堂（圣洛伦索、圣马丁、圣米兰和拉韦拉克鲁斯）外墙表面、有生物劣化明显迹象的白云岩和石灰岩样本。通过扫描电子显微镜分析了在岩石基质上形成的生物膜。记录了样本中发现的最常见地衣种类。然后从这些碳酸盐岩中获得真菌培养物，并通过对内部转录间隔区（ITS）进行测序来进行表征。通过背散射电子模式的扫描电子显微镜观察到，真菌（地衣化和非地衣化）是在有生物劣化迹象的部位出现最频繁的微生物。定殖过程尤其受到这些建筑物所用石材孔隙率特征的制约。在白云岩中，微生物主要占据岩石晶间孔隙组成的空间，而在生物碎屑白云石化石灰岩中，真菌定殖似乎与模孔孔隙率更相关。微生物生物膜与基质紧密接触，因此可能会对下层材料造成显著劣化。我们描述了真菌定殖引起的石材蚀变的不同过程，并讨论了这些过程对防止生物劣化处理设计的影响。
