Deterioration of an Etruscan tomb by bacteria from the order Rhizobiales.

The Etruscan civilisation originated in the Villanovan Iron Age in the ninth century BC and was absorbed by Rome in the first century BC. Etruscan tombs, many of which are subterranean, are one of the best representations of this culture. The principal importance of these tombs, however, lies in the wall paintings and in the tradition of rich burial, which was unique in the Mediterranean Basin, with the exception of Egypt. Relatively little information is available concerning the biodeterioration of Etruscan tombs, which is caused by a colonisation that covers the paintings with white, circular to irregular aggregates of bacteria or biofilms that tend to connect each other. Thus, these colonisations sometimes cover extensive surfaces. Here we show that the colonisation of paintings in Tomba del Colle is primarily due to bacteria of the order Rhizobiales (Alphaproteobacteria), which were likely influenced by the neighbouring rhizosphere community and the availability of nutrients from root exudates.

Biodeterioro de monumentos y biorremediación: estado actual y perspectivas futuras / Monuments biodeterioration and bioremediación: current condition and future perspectives

Durante siglos se ha intentado detener el proceso natural de destrucción de la piedra en construcciones y monumentos mediante obras de mantenimiento y reparación, usando técnicas y materiales tradicionales en siglos pasados como los morteros de cal y arena. A partir de la segunda mitad del siglo XX, se introducen los materiales poliméricos y sintéticos. En las últimas décadas, con el desarrollo de la biotecnología, las propuestas de restauración han cambiado drásticamente y se suponen superiores a los métodos tradicionales. Sin embargo, en algunos casos, los resultados no parecen convincentes. En la primera década del siglo XXI se está prestando una especial atención a la producción de calcita por bacterias en relación con un proceso de consolidación de la piedra deteriorada. La limpieza de frescos y pinturas con enzimas o mediante tratamiento con bacterias es otro de los temas que despierta una especial atención en la restauración y conservación de monumentos. La biotecnología tiene mucho que ofrecer pero debe superar las barreras que actualmente la convierten en una técnica prometedora en el campo de la conservación del patrimonio aunque, aún, de difícil aplicación a monumentos. Su utilización se efectúa en ensayos u objetos de dimensiones abarcables, mientras que su aplicación a escala industrial está aún por desarrollar (AU)

For centuries the man has tried to stop the natural process of deterioration of the building stones and monuments through maintenance and repairing works, using traditional techniques and materials such as mortar of lime and sand. From the second half of the 20th century, polymer and synthetic materials were introduced in conservation. In recent decades, with the application of biotechnology, the restoration proposals have changed dramatically and are supposed to be superior to traditional methods. However, in some cases, the results do not seem convincing. In the first decade of the 21st century a special attention is being paid to the production of calcite by bacteria as a process of consolidation of deteriorated stone. Cleaning of frescoes and paintings by enzymes or bacterial treatments are another issues that arouses a special attention in the restoration and conservation of monuments. Biotechnology has much to offer but must overcome the barriers that currently make it a promising technique in the field of cultural heritage conservation though, even, of difficult application to monuments. Currently, their use is restricted to test on object of manageable size, while its implementation on an industrial scale is yet to be developed (AU)

Did smoke from the Kuwait oil well fires affect Iranian archaeological heritage?

The combustion of crude oil produces a wide range of pollutants, including gases, volatile organic compounds, polycyclic aromatic hydrocarbons, acid compounds (e.g., sulfuric acid), and soot. Several of these pollutants have been linked with the deterioration and blackening of monuments. The paper reports the results of an investigation on the causes of the soiling of cultural remains at important archaeological sites in the provinces of Khuzestan and Fars, in southern Iran, assumed to be an effect of the Persian Gulf oil well fires of 1991. Different analytical techniques were applied to characterize the mineralogical composition of the damage layers, investigate the deposition of atmospheric particles, measure the anion concentrations, and identify and quantify the carbon components. The results showed that the black deposits on the surfaces of the Iranian monuments considered are mainly microbiotic crusts produced by cyanobacterial growth. No evidence was found of the deposition of particulate matter (smoke) produced by the Kuwait oil fires during the Gulf War.

Agromyces italicus sp. nov., Agromyces humatus sp. nov. and Agromyces lapidis sp. nov., isolated from Roman catacombs.

A polyphasic study was carried out to clarify the taxonomic positions of three Gram-positive isolates from the Catacombs of Domitilla, Rome (Italy). 16S rRNA gene sequence comparisons placed these strains within the genus Agromyces. The morphological and chemotaxonomic characteristics of these isolates were consistent with the description of the genus Agromyces. The three isolates could be readily distinguished from one another and from representatives of all Agromyces species with validly published names by a broad range of phenotypic characteristics and DNA-DNA relatedness studies. Therefore, these isolates are proposed to represent three novel species of the genus Agromyces, Agromyces italicus sp. nov. (type strain CD1(T)=HKI 0325(T)=DSM 16388(T)=NCIMB 14011(T)), Agromyces humatus sp. nov. (type strain CD5(T)=HKI 0327(T)=DSM 16389(T)=NCIMB 14012(T)) and Agromyces lapidis sp. nov. (type strain CD55(T)=HKI 0324(T)=DSM 16390(T)=NCIMB 14013(T)).

Phylogenetic diversity of bacteria associated with Paleolithic paintings and surrounding rock walls in two Spanish caves (Llonín and La Garma).

Bacterial diversity in caves is still rarely investigated using culture-independent techniques. In the present study, bacterial communities on Paleolithic paintings and surrounding rock walls in two Spanish caves (Llonín and La Garma) were analyzed, using 16S rDNA-based denaturing gradient gel electrophoresis community fingerprinting and phylogenetic analyses without prior cultivation. Results revealed complex bacterial communities consisting of a high number of novel 16S rDNA sequence types and indicated a high biodiversity of lithotrophic and heterotrophic bacteria. Identified bacteria were related to already cultured bacteria (39 clones) and to environmental 16S rDNA clones (46 clones). The nearest phylogenetic relatives were members of the Proteobacteria (41.1%), of the Acidobacterium division (16.5%), Actinobacteria (20%), Firmicutes (10.6%), of the Cytophaga/Flexibacter/Bacteroides division (5.9%), Nitrospira group (3.5%), green non-sulfur bacteria (1.2%), and candidate WS3 division (1.2%). Thirteen of these clones were most closely related to those obtained from the previous studies on Tito Bustillo Cave. The comparison of the present data with the data obtained previously from Altamira and Tito Bustillo Caves revealed similarities in the bacterial community components, especially in the high abundance of the Acidobacteria and Rhizobiaceae, and in the presence of bacteria related to ammonia and sulfur oxidizers.

Phylogenetic 16S rRNA analysis reveals the presence of complex and partly unknown bacterial communities in Tito Bustillo cave, Spain, and on its Palaeolithic paintings.

Tito Bustillo cave (Ribadesella, Spain) contains valuable Palaeolithic paintings, which date back 15 000-20 000 years. Since 1969, the cave has been open to the public. Rock wall surfaces, spelaeothems and soils are covered by apparent biofilms of phototrophic microorganisms, which develop under artificial lighting. In addition, rock surfaces present conspicuous bacterial growth in the form of round colonies of different colours and about 1-2 mm in diameter. Even the famous Paintings Panel shows some evident microbial growth. In the present study, bacterial communities on the paintings and on the rock surfaces near the paintings were analysed by culture-independent techniques, including polymerase chain reaction (PCR) amplification of bacterial 16S rRNA genes (16S rDNA), phylogenetic sequence analyses and genetic community fingerprinting by denaturing gradient gel electrophoresis (DGGE). DGGE fingerprints showed complex bacterial community patterns. Forty-one clones matching DGGE bands of the community fingerprints were sequenced, representing about 39% of DNA fragments in the DGGE patterns. Phylogenetic sequence analyses revealed a high number of phylogenetically novel 16S rDNA sequence types and a high diversity of putatively chemotrophic and heterotrophic bacteria. Sequences were phylogenetically most closely related to the Proteobacteria (20 clones), green non-sulphur bacteria (three clones), Planctomycetales order (one clone), Cytophaga-Flexibacter- Bacteroides division (one clone) and the Actinobacteria (four clones). Furthermore, we report the presence of members of the Acidobacterium division (12 clones) in a karstic hypogean environment. Members of this phylum have not so far been detected in these particular environments.