Effect of different iodine formulations on the expression and activity of Streptococcus mutans glucosyltransferase and fructosyltransferase in biofilm and planktonic environments

Objectives: The glucosyltransferase (GTF) and fructosyltransferase (FTF) enzymes play a pivotal role in dental biofilm formation as they synthesize polysaccharides that act as the extracellular matrix of the biofilm. Iodine is a unique antibacterial agent that has distinct properties from other conventional antibacterial agents. In this study we have examined the effect of iodine and povidone iodine (PI) on gtf andftfexpression in biofilm and planktonic environments and on immobilized and unbound GTF and FTF activity. Methods: Real-time reverse transcription-PCR was used to investigate the effect of iodine and PI on ftf,gtfB and gtfC expression. The effect of iodine and PI on GTF and FTF activity was tested using radioactive assays. Results: Our results indicate that iodine and PI in a tetraglycol carrier cause enhancement of expression of gtfB in Streptococcus mutans in biofilms but not in planktonic bacteria. PI in water induced expression of gtfB and gtfC in planktonic bacteria. However, iodine and PI strongly inhibit polysaccharide production by GTF and to a lesser extent by FTF activity. The inhibitory effect on GTF activity was similar in solution compared to its activity in the immobilized environment. This unique effect may be attributed to the distinct chemical properties of iodine compared with other antibacterial agents. Conclusions: This study indicates that iodine at sub-bactericidal concentrations demonstrates molecular and enzymatic effects that are highly associated with biofilm formation.