Back to the past-forever young: cutting-edge biochemical and microbiological tools for cultural heritage conservation.

Ancient documents and milestones of human history such as manuscripts and textiles are fragile and during aging undergo chemical, physical, and biological deterioration. Among the different causes of damage, also human intervention plays a role since some restoration strategies proved to be transient and/or they generated further damage. Outdoor monuments undergo deterioration since they are exposed to pollution, weathering, microbial attack (giving rise to undesired pigmentation, discoloration or true dissolution, corrosion, and overall decay), as well as man-made damage (i.e., graffiti). This review article reports the best-fitting strategies used to restore wall paintings, outdoor monuments, textiles, and paper documents to their ancient beauty by employing "soft" biobased approaches such as viable bacteria or suitable enzymes.