Microbes for Archaeological Iron Artworks

Archaeological iron artefacts encounter serious post-excavation problems when contaminated with salts. In fact, once excavated, the exposure to a higher oxygen concentration and lower relative humidity renders the corrosion crust formed during burial not longer stable.

We propose here to exploit the unique properties of some microorganisms for the stabilization of archeological iron. To this purpose, three different strategies will be adopted either leading to the formation of stable compounds of low molar volume or using chloride-translocation properties.

Tests will be achieved with the precipitation of iron oxalates by Beauveria bassiana. The same approach will be exploited to precipitate magnetite (Fe3O4), another very stable compound of low molar volume, using microorganisms reported in the literature for the biosynthesis of magnetite nanoparticles: Fusarium oxysporum or Verticillium sp. or magnetotactic bacteria.

Photo                                                                                                                                                                                                                 Beauveria bassiana cultures on malt-agar medium with an iron washer. a) Optical microscopy observations. b) Secondary electron image. c) Transmittance FTIR spectrum (4000–650cm−1) obtained from hyphae incrusted with red crystals. Results achieved during the master thesis of S. Cario “Etude et optimisation de la formation d’oxalates d’origine pour la conservation d’objets en cuivre, fer et argent»


In order to enhance the removal of chloride ions from the iron object, the possible translocation of those by fungi will be studied. In chlorine-rich environments, some species of fungi develop strategies for detoxify their surrounding from the toxic chlorine. These halophiles will be isolated and cultured from natural places such as salt lakes. In addition, white-rot fungi are also studied in bioremediation for allowing chlorine migration.

Based on the results achieved, we could contribute to the development of a synergetic microbial consortium specially designed for the removal of chloride ions and the simultaneously formation of stable iron compounds. Particular attention will be devoted to the efficiency and the impact on metallographic structure of the proposed treatment to overcome the problems associated with the treatments in use nowadays. Real samples will be also included in this study in order to validate the new methodology. This research issue presents innovative aspects in biogeochemistry of micro-organisms and conservation science.


Other institutes involved in the project :

  • Laboratory LAMUN
  • Haute Ecole Arc Conservation-Restauration , University of applied sciences Western Switzerland
  • Swiss National Institute for Technology in Lausanne (EPFL)
  • Zurich Swiss National Museum


Edith Joseph, assistant professor


Sarah James, PhD


Lidia Mathys-Panaguzzi, lab technician