Biofilms. (cover story)

BIOFILMS; MICROBIAL aggregation; MICROBIAL ecology; MICROORGANISMS; MICROBIAL growth; BACTERIA

This article focuses on biofilms, or microbial communities. The residents of the biofilm may be a single species or a diverse group of microorganisms distributed in various neighborhoods. Their common bond is a matrix made of polysaccharides, DNA and proteins. A microorganism's extraordinary ability to spread explains how biofilms show up in the unlikeliest of places. Perhaps one of the most extraordinary environments where one can find a biofilm is in the belly of a dairy cow. Biofilms are part of the normal complement of microbes in many healthy animals. Animals aren't the only living things that provide a home to biofilms. Microbial colonies have been recognized on tropical plants and grocery-store produce since the 1960s, but it wasn't until the past decade that the term biofilm was used to describe bacterial growth on a plant's surface. The Centers for Disease Control and Prevention estimates that up to 70 percent of the human bacterial infections in the Western world are caused by biofilms. This includes diseases such as prostatitis and kidney infections, as well as illnesses associated with implanted medical devices such as artificial joints and catheters and the dental diseases--both tooth decay and gum disease--that arise from dental plaque, a biofilm. In almost all instances, the biofilm plays a central role in helping microbes survive or spread within the host.