ORIGINAL PAPER Isolation of five Rubrobacter strains from biodeteriorated monuments L. Laiz & A. Z. Miller & V. Jurado & E. Akatova & S. Sanchez-Moral & J. M. Gonzalez & A. Dionísio & M. F. Macedo & C. Saiz-Jimenez Received: 11 March 2008 / Revised: 7 September 2008 / Accepted: 14 September 2008 / Published online: 25 October 2008 # Springer-Verlag 2008 Abstract In the last few years, the microbial colonisation of mural paintings in ancient monuments has been attract- ing 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 environ- ments. 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. Keywords Rubrobacter . Efflorescences . Biodeterioration . Mural paintings . Struvite Introduction In the last decade, the topic of microbial colonisation and biodeterioration of mural paintings in ancient monuments or of plaster walls in churches has been attracting the attention of microbiologists and conservators (Rölleke et al. 1998; Ciferri 1999; Gurtner et al. 2000; Piñar et al. 2001). Many different phenomena can be observed—the most commonly reported include efflorescence formation, detachment, colour changes, overgrowth of green photosynthetic biofilms, etc. In the initial stages of colonisation, growth of micro- organisms on a mural painting causes only aesthetic damage, since there is little or no alteration of the painted surface. Later, cells and hyphae penetrate the painted layer, and chemical attack results in pitting, detachment, cracking, and loss of the paint. This damage is added to by microbial metabolites, which often modify the original colour, some- times producing red or pink pigmentation (Schabereiter- Gurtner et al. 2001; Tiano and Tomaselli 2004; Realini et al. 2005; Imperi et al. 2007). Schabereiter-Gurtner et al. (2001) investigated the wall paintings of two historical buildings in Austria and Germany, where a correlation between Rubrobacter-related bacteria and the phenomenon of rosy discolouration of masonry and lime wall paintings was found. Similar data were obtained by Ortega-Morales et al. (2004) and Imperi et al. (2007). However, those authors failed to isolate any Rubrobacter strain. Naturwissenschaften (2009) 96:71–79 DOI 10.1007/s00114-008-0452-2 L. Laiz : V. Jurado : E. Akatova : J. M. Gonzalez : C. Saiz-Jimenez (*) Instituto de Recursos Naturales y Agrobiologia, CSIC, Apartado 1052, 41080 Seville, Spain e-mail: saiz@irnase.csic.es A. Z. Miller : M. F. Macedo Departamento de Conservação e Restauro, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisbon, Portugal S. Sanchez-Moral Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain A. Dionísio Laboratório de Mineralogia e Petrologia, Departamento de Engenharia de Minas e Georrecursos, Instituto Superior Técnico, Lisbon, Portugal