Development, Characterization and Ecological Implications of a Smooth Colony Variant of Biofilm-forming Cariogenic Streptococcus mutans

The development of dental caries has been an important topic in oral microbiology research for several decades. One of the common strains of bacteria oral Streptococcus mutans, has long been considered the primary bacterium involved in the initiation and progression of dental caries. One of the primary virulence traits of S. mutans is sucrose-dependent biofilm formation. However, beginning in the 1970s, several researchers have observed a naturally derived variant of S. mutans defective in biofilm formation, and there have since been numerous studies on this variant. The mechanism of the appearance of this variant has been well established, but little is known about its ecological significance. Additional studies will be needed to advance our understanding of the role and behavior of this colony variant within the oral cavity. In this review, we summarize the development and characterization of this naturally derived variant, and discuss its ecological implications in the oral habitat.