Inhibitors of biofilm damage on mineral materials (BIODAM)

Scientific approaches to the safeguarding of stone monuments have evolved over the years to reach a high level of sophistication. Analysis and treatment of detrimental biofilms has also made progress. One factor is the awareness not only of biologically initiated chemical but also physical and mechanical damage functions. Another line of evolution of techniques and application proposals is the application of biocidal chemicals. However, in the past 20 years, these have been increasingly banned because of environmental and health hazards produced by these highly toxic substances. In this communication we give an outline of a project, in which chemical, physical, geological and microbiological knowledge is combined in order to find less dangerous ways to eliminate or inhibit detrimental microbial growth on and in rocks and other mineral materials. Special attention is given to the detrimental effects of poikilophilic algal, cyanobacterial and especially fungal films and networks. Biocidal products, including photodynamic treatments, are combined with pigment and exopolysaccharide inhibitors and cell wall permeabilizers to make biofilms vulnerable to chemicals able to kill the associated micro-organisms.