Amylolytic and Proteolytic Bacteria in Deteriorated Paper-based Historical Manuscripts

Amylolytic and proteolytic bacteria in the historical manuscripts can consume vegetable and animal based surface coating substances and adhesives which are found on the raw paper as a protective layer. Therefore, the presence of these bacteria in the historical manuscripts may pose a risk to the integrity of them. Moreover, the presence of bacteria showing enzymatic activities may cause a more serious threat to the deterioration of the historical manuscripts. In this study, it was mainly aimed to detect bacteria having all 3 enzymes together, amylase, caseinase and gelatinase, in the historical manuscripts. For this purpose, 10 historical manuscripts in the Süleymaniye Manuscript Library were screened for bacteria capable of producing amylase, caseinase and gelatinase enzymes and then the isolates found to produce all of these enzymes were identified by molecular methods. The obtained 85 bacterial isolates, 64%, 79%, and 53%, respectively, showed amylase, caseinase, gelatinase activity. Twenty-seven isolates (32%) were found to produce all of these 3 enzymes. Among these bacteria, amylase showed the highest hydrolysis ability in terms of enzyme index value. The bacteria were mainly included in the Bacillus genus belonging to the Firmicutes phylum (81%). The bacterial species with the highest hydrolysis zones for all 3 enzymes belonged to the genus Bacillus. The results may indicate that historical manuscripts using starch as surface coating and adhesive may be more susceptible to microbial damage, especially by the Bacillus genus.