Halophilic microorganisms are responsible for the rosy discolouration of saline environments in three historical buildings with mural paintings

13 páginas.-- 5 figuras.-- 2 tablas.-- 64 referencias.-- Material suplementario (1 firura.-- 4 tablas).-- The ribosomal sequences of the bacterial- and archaeal clones and the bacterial isolates have been deposited at the NCBI GenBank database under the accession numbers (KF692550–KF692709 for the cloned sequences and HG515390–HG515401 for the bacterial isolates).

A number of mural paintings and building materials from monuments located in central and south Europe are characterized by the presence of an intriguing rosy discolouration phenomenon. Although some similarities were observed among the bacterial and archaeal microbiota detected in these monuments, their origin and nature is still unknown. In order to get a complete overview of this biodeterioration process, we investigated the microbial communities in saline environments causing the rosy discolouration of mural paintings in three Austrian historical buildings using a combination of culturedependent and -independent techniques as well as microscopic techniques. The bacterial communities were dominated by halophilic members of Actinobacteria, mainly of the genus Rubrobacter. Representatives of the Archaea were also detected with the predominating genera Halobacterium, Halococcus and Halalkalicoccus. Furthermore, halophilic bacterial strains, mainly of the phylum Firmicutes, could be retrieved from two monuments using special culture media. Inoculation of building materials (limestone and gypsum plaster) with selected isolates reproduced the unaesthetic rosy effect and biodeterioration in the laboratory

JE, GP and KS were partly financially supported with funding provided from the Ministry of Care of Monuments in Austria (Bundesdenkmalamt). Further funding was provided by the University of Natural Resources and Life Sciences (Vienna). CSJ, VJ and AZM acknowledge support from project Consolider project from the Spanish Ministry (CSD) 2007-00058. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Peer reviewed