Physiologic homeostasis and stress responses in oral biofilms.

Studies performed since the early, 1970s have yielded tremendous amounts of information about the physiology, genetics, and interactions of oral bacteria. This pioneering work has provided a solid foundation to begin to apply the knowledge and technologies developed using suspended populations for studying oral bacteria under conditions that more closely mimic conditions in the oral cavity, in biofilms. Our current understanding of phenotypic capabilities of individual and complex mixtures of adherent oral bacteria is in its infancy. There is ample evidence that oral streptococci have different patterns of gene expression than planktonic cells, but we have little understanding of the basis for these observations. Even in biofilmforming bacteria with very well-developed genetic systems it is only very recently that genetic loci involved in biofilm formation and responses to surface growth have been identified. A comprehensive study of the physiology and gene expression characteristics of adherent oral bacteria not only will enhance our abilities to control oral diseases, but it will provide critical information that can be applied to a variety of other pathogenic microorganisms.