Functional Bacterial Amyloids in Biofilms

Abstract

Functional bacterial amyloids constitute a group of important proteina- ceous surface structures. Most amyloids are highly insoluble in water and resistant to most enzymes and thermal and chemical denaturants. Their functions in bacteria are still not well described but seem to include fimbriae and other cell appendages for adhesion and biofilm formation, cell envelope components, spore coating, formation of large extracellular structures, amyloids acting as cytotoxins and probably several others, as yet unknown. Very few bacterial amyloids have been purified and investigated in depth. Details about the biophysical properties and ecological significance are restricted to E. coli, some pseudomonads and a few other bacteria. Recently, we have found that functional amyloids are widespread among microorganisms in biofilms in nature and in engineered systems, indicating that these surface structures are substantially more diverse in structure and function than hitherto anticipated. In this chapter, we highlight some of these recent results and discuss the ecological importance of amyloid surface structures in bacteria.