Biofilms: recent developments on an old battle.

Microbial cells are able to adhere to surfaces and through an exo-polymeric matrix they establish microbial communities known as biofilms. This form of immobilised biomass can be responsible for heat and mass transfer limitations in industrial processes and be a source of contamination and proliferation of infections in water supply systems and medical devices. Several processes to prevent and destroy biofilms in surfaces and tissues have been patented and the new developments are reviewed. Most of the patents propose the use of UV radiation, high temperatures and addition of oxidant compounds to clean surfaces, which may be protected by antimicrobial coatings containing metal ions, non-pathogenic bacteria, time-release agents and biocides. Several biocidal compositions, comprising mixtures of disinfectants and biocides, are also presented. Mechanical, chemical and enzymatic procedures are discussed and particular emphasis is given to the cleaning and protection of medical devices and water supply systems.