BackgroundThe prosperity of Hallstatt (Salzkammergut region, Austria) is based on the richness of salt in the surrounding mountains and salt mining, which is documented as far back as 1500 years B.C. Substantial archaeological evidence of Bronze and Iron Age salt mining has been discovered, with a wooden staircase (1108 B.C.) being one of the most impressive and well preserved finds. However, after its discovery, fungal mycelia have been observed on the surface of the staircase, most probably due to airborne contamination after its find.ObjectiveAs a basis for the further preservation of this valuable object, the active micro-flora was examined to investigate the presence of potentially biodegradative microorganisms.ResultsMost of the strains isolated from the staircase showed to be halotolerant and halophilic microorganisms, due to the saline environment of the mine. Results derived from culture-dependent assays revealed a high fungal diversity, including both halotolerant and halophilic fungi, the most dominant strains being members of the genus Phialosimplex (synonym: Aspergillus). Additionally, some typical cellulose degraders, namely Stachybotrys sp. and Cladosporium sp. were detected. Numerous bacterial strains were isolated and identified as members of 12 different genera, most of them being moderately halophilic species. The most dominant isolates affiliated with species of the genera Halovibrio and Marinococcus. Halophilic archaea were also isolated and identified as species of the genera Halococcus and Halorubrum. Molecular analyses complemented the cultivation assays, enabling the identification of some uncultivable archaea of the genera Halolamina, Haloplanus and Halobacterium. Results derived from fungi and bacteria supported those obtained by cultivation methods, exhibiting the same dominant members in the communities.ConclusionThe results clearly showed the presence of some cellulose degraders that may become active if the requirements for growth and the environmental conditions turn suitable; therefore, these microorganisms must be regarded as a threat to the wood.
Recent investigations have shown that xerophilic fungi may pose a biodeterioration risk by threatening objects of cultural heritage including many types of materials, including wood, paint layers, organic glues or leather and even metal. Historic—and also new built—pipe organs combine all those materials. In this study, halotolerant aspergilli and penicillia with low optimal temperatures were shown to be the most frequent invaders of pipe organs. The fungi form white mycelia on the organic components of the organs with a clear preference for the bolus paint of the wooden pipes, the leather-made hinges of the stop actions and all parts fixed by organic glue. Physiological tests showed that the strains isolated from the instruments all show a halotolerant behavior, although none was halophilic. The optimum growth temperature is below 20 °C, thus the fungi are perfectly adapted to the cool and relatively dry conditions in the churches and organs respectively. The de-novo genome sequences analyses of the strains are currently ongoing and will reveal the genomic basis for the halotolerant behavior of the fungi.
The Museo Egizio in Turin holds a unique collection of 116 mummified or skeletal human bodies or body parts. This collection is currently under study by the "Mummy Conservation Project", a collaborative venture of the Museo Egizio, the Institute for Mummy Studies of Eurac Research, the Soprintendenza Archeologia del Piemonte, and the Horus Group, whose aim is to improve mummy conservation techniques. In the context of this project, an assessment of the state of preservation of the mummified human remains was carried out by monitoring basic physical parameters (temperature, relative humidity and water activity) and by performing a fungal survey. The latter revealed the presence on the mummified material of fungal spores and mycelia that could possibly pose a biodegradative threat. However, all the current physical parameters show that the mummies are stored under optimal environmental conditions, which will suppress any microbial up-growth.
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