Biodegradation of Cultural heritage

Our cultural heritage is composed of a variety of natural materials used to construct a number of artefacts from simple mono-components to complex structures integrating both inorganic and organic matters.

All objects of cultural heritage, including those constructed from the more durable stones (e.g. sandstone, granite, plaster, bricks, etc.) are influenced by environmental factors that can modify their structure and composition. Furthermore, the “biosphere” subjects these constructions to biological decay. This biotransformation or biodeterioration process takes place across the world, but is more prevalent and destructive in warm and humid climates, as found in India, where environmental conditions favour the growth of most organisms.

There is general consensus among conservators and conservation scientists that the alteration of stone monuments due to living organisms is usually indicative of an advanced state of deterioration. Biodeterioration of stone is a complex and multifaceted problem, the understanding and treatment of which calls for cooperation among scientists from a variety of disciplines.

Work conducted by ASI and Janssen Pharmaceutica 2005-2008

The two sites earmarked for the first phase of this collaboration were the Tipu Sultan Palace in Srirangapatna and the Hampi complex World Heritage Site, both in Karnataka.

In the initial stage, ASI provided information to Janssen Preservation and Material Protection (PMP) on previous treatments used at the sites to combat the effects of biodeterioration. On the basis of this information, Janssen PMP was able to culture microbiological samples from both sites, which allowed the specific fungi present to be identified. Eight species were identified from each site.

This work was followed up with a site visit by Janssen PMP to identify further biodeteriogens, such as unwanted weed growth and Tolypothrix­-dominated black biofilm.

Laboratory work at Janssen PMP was successful in determining the sensitivity of the relevant fungi to four specific, state-of-the-art, organic fungicides, which has eventually led to the provision of three antifungal formulations for ASI to test on-site.

The investigative work was further developed following a visit by Belgian experts from the Raimond Lemaire International Centre for Conservation, Faculty of Engineering, Catholic University of Leuven and Monumentenwacht Vlaanderen vzw., which focused on identifying the structural, documentation and preventive needs and risks of the Hampi site.

In addition, a joint workshop on Biodeterioration, Preservation and Conservation of Monuments was organised by ASI and Janssen Pharmaceutica and held in Chennai on 18 and 19 September 2008.