Biocleaning of Cultural Heritage stone surfaces and frescoes: which delivery system can be the most appropriate?

The use of the advanced biotechnology of microbiological systems for the biological cleaning of Cultural Heritage has been recently improved and optimized taking into the account of different factors. Biocleaning systems have been indeed applied to historic buildings, statues and frescoes, developing new techniques and optimising and refining the existing ones. These systems remove alterations forms like sulfate and nitrate crusts and organic substances like animal glue in a more effective, less invasive way than the traditional cleaning techniques. This review focuses on several delivery systems (sepiolite, hydrobiogel-97, cotton wool, carbogel, mortar and alginate beads, agar and arbocel) used for the biocleaning of Cultural Heritage, comparing their main properties and characteristics and making a critical evaluation on how easy they can be applied and on their future potentiality as ready-to-use and risk-free formulates. Therefore this review will help conservation scientists, conservator-restorers and researchers in the field to choose the most appropriate delivery system for any specific applications.