In this study, we show that moonmilk subaerial speleothems in Altamira Cave (Spain) consist of a network of fiber calcite crystals and active microbial structures. In Altamira moonmilks, the study of the typology and distribution of fiber crystals, extracellular polymeric substances, and microorganisms allowed us to define the initial stages of fiber crystal formation in recent samples as well as the variations in the microstructural arrangement in more evolved stages. Thus, we have been able to show the existence of a relationship among the different types of fiber crystals and their origins. This allowed us to outline a model that illustrates the different stages of formation of the moonmilk, developed on different substrata, concluding that microbes influence physicochemical precipitation, resulting in a variety of fiber crystal morphologies and sizes.

No abstract

The paintings from Tomba della Scimmia, in Tuscany, are representative of the heavy bacterial colonization experienced in most Etruscan necropolises. The tomb remained open until the late 70′s when it was closed because of severe deterioration of the walls, ceiling and paintings after decades of visits. The deterioration is the result of environmental changes and impacts suffered since its discovery in 1846. We show scanning electron microscopy and molecular studies that reveal the extent and nature of the biodeterioration. Actinobacteria, mainly Nocardia and Pseudonocardia colonize and grow on the tomb walls and this process is linked to the availability of organic matter, phyllosilicates (e.g. clay minerals) and iron oxides. Nocardia is found metabolically active in the paintings. The data confirm the specialization of the genera Nocardia and Pseudonocardia in the colonization of subterranean niches.

No abstract

In the last few years, the microbial colonisation of mural paintings in ancient monuments has been attracting the attention of microbiologists and conservators. The genus Rubrobacter is commonly found in biodeteriorated monuments, where it has been reported to cause rosy discolouration. However, to date, only three species of this genus have been isolated, all from thermophilic environments. In this paper, we studied three monuments: the Servilia and Postumio tombs in the Roman Necropolis of Carmona (Spain), and Vilar de Frades church (Portugal), in search of Rubrobacter strains. In all cases, biodeterioration and the formation of efflorescences were observed, and five Rubrobacter strains were isolated. These isolates showed different physiology and migration in denaturing gradient gel electrophoresis, suggesting they might represent new species within this genus. The isolates reproduced some biodeterioration processes in the laboratory and revealed their biomediation in crystal formation.

With today's leisure tourism, the frequency of visits to many caves makes it necessary to know about possible potentially pathogenic microorganisms in caves, determine their reservoirs, and inform the public about the consequences of such visits. Our data reveal that caves could be a potential danger to visitors because of the presence of opportunistic microorganisms, whose existence and possible development in humans is currently unknown. Caves, bacteria, fungi, virus, opportunistic pathogens Received 26 Oktober 2009; Revised 28 November 2009; Accepted 9 December 2009. or have lowered defences. Unfortunately, information on this topic is not well known, and visitors remain unaware. Determining the extent of the potential danger is of great interest -not only scientific, but also medical and social. Our data reveal that caves could be a potential danger to visitors, because of the presence of opportunistic microorganisms, whose existence and possible development in humans is currently unknown. Keywords: CAVE MICROORGANISMSMicroorganisms occupy all the niches of the biosphere, including subterranean ones. Underground habitats, represented essentially by caves, have no light, little or no organic nutrient load, a relatively constant temperature, and extensive areas of mineral surfaces.The literature on microbial communities in subterranean environments is scant and chiefly restricted to caves found in Spain, Italy, France, Rumania, and the USA. Most of the existing literature refers to specific aspects, such as the taxonomic or geomicrobiological ones (Hernandez-Marine & Canals, 1994;Northup & Lavoie, 2001; Engel et al., 2003; Barton, & Northup, 2007; Barton et al., 2007; Porter et al. 2009), to the effects on rock-art paintings (Schabereiter-Gurtner et al., 2002 a, b), or colonization by fungi (Dupont et al., 2007; Bastian et al., 2009b).A review on the biodiversity and distribution of

a b s t r a c tThe aim of this study is the comparison between different treatments (anatase and two conventional biocides: Biotin T and Anios) for preventing biodeterioration of mortars. The treatments were applied both in the laboratory on mortar slabs and in situ on walls of Palácio Nacional da Pena (Sintra, Portugal). Mortar slabs treated with anatase (pure and Fe 3þ doped) applied as a coating or by mixing within the mortar were prepared, and their surfaces characterized by different methodologies. The mortars were inoculated with cyanobacteria and chlorophyta species, incubated for a period of 4 months and the chlorophyll content quantified by extraction method and fluorescence emission. For comparison purposes untreated mortar slabs were inoculated, incubated and finally treated with the biocides. After two weeks the respective chlorophyll contents was quantified.In situ studies in two external walls of Palácio Nacional da Pena covered by organisms were also performed by direct application of aqueous solutions of the three products, and the efficiency of the treatment monitored by spectrophotometry using the CIELAB method. Lichens and other phototrophic microorganisms were identified by direct observation with a microscope and cyanobacteria, green microalgae, bacteria and fungi by DNA-based molecular analysis targeting the 16S and 18S ribosomal RNA genes.The results show that anatase is a better agent for preventing biodeterioration than the two tested conventional biocides, both in mortars slabs and in situ studies. In fact, photographic and colorimetric records made in two external walls of Palácio Nacional da Pena after two weeks of treatments application showed that lichens and other phototrophic microorganisms disappear from the places where anatase was applied.

No abstract