Vallès 1 . Biofilms on rocks

Microorganisms group themselves into assemblies known as communities or biofilms, which are associated with surfaces. A matrix of self-segregated polymeric substances enhances their attachment. Communication between bacterial cells involves the production and detection of diffusible signal molecules, known as quorum sensing, which is an important regulatory mechanism of biofilm strategies. Biofilms thrive everywhere; in subaerial surfaces they can be driven by sunlight, with photosynthesizing components. A special case is those which colonize works of art, forming patinas and becoming involved in the degradation of colonized substrata. Knowledge of threedimensional structure of the biofilm and the distribution of species concerned is crucial for managing and preventing uncontrolled colonization and for preserving cultural heritage sites. This paper describes their role in this degradation, some examples of biofilms and their resilience mechanisms. The methods used in their study when growing in monuments and caves are also discussed.