Biocleaning of historical documents: The use and characterization of bacterial enzymatic resources

Abstract Living microorganisms have been used for biocleaning of cultural heritage items, but the application of only extracellular enzyme mixtures (EEMs) from isolated bacteria has not previously been considered for biorestoration work. In this investigation, the proteolytic characteristics of the EEMS from three bacterial isolates ( Paracoccus sp., Bacillus flexus and Exiguobacterium undae ) were determined and their extent of inhibition in the presence of the proteolytic inhibitors 1,10-phenanthroline monohydrate, EDTA, leupeptin, bestatin and various metal ions was examined. These EEMs were used to remove the animal glue present on the spine of bound newspapers. FT-IR analysis showed that animal glue was effectively removed by a solution of tylose and EEM. The EEM of E. undae gave the best results. Our study describes a simple strategy for the production and characterization of enzymatic mixtures targeted to the degradation of a specific substrate and their subsequent use for biocleaning historical objects.