A New Theory of Biodeterioration of Heritage Materials Focussed on Complexity

In the last decade, it has become clear that damage to material due to microorganisms is chemically and biologically more intricate than previously imagined and that the agents are often multiple and entangled by ecological relationship. The use of techniques based on the analysis of DNA extractable from material and its massive sequencing have led to the understanding of the high variability associated with microbiological deterioration of library material. Manuscripts, printed books and archival material are often unique objects with manufacturing characteristics that make the variables contributing to their biodeterioration challenging to circumscribe. In this review, three main mechanisms of microbiological attack are described, and some innovative emerging approaches used to evaluate them are commented. In particular, technologies based on environmental DNA (eDNA) provide information on the microbes, but also on aspects concerning biocodicology and archaeology. These advancements suggest that a new theory of biodeterioration is needed, which considers the complexity of both phenomena and material.