Bacteria that accumulate polyphosphates have previously been shown to dynamically influence the solubility of phosphatic minerals in marine settings and wastewater. Here, we show that dental plaque, saliva, and carious lesions all contain abundant polyphosphate-accumulating bacteria. Saturation state modeling results, informed by phosphate uptake experiments using the model organism Lactobacillus rhamnosus, which is known to inhabit advanced carious lesions, suggest that polyphosphate accumulation can lead to undersaturated conditions with respect to hydroxyapatite under some oral cavity conditions. The cell densities of polyphosphate-accumulating bacteria we observed in some regions of oral biofilms are comparable to those that produce undersaturated conditions (i.e., those that thermodynamically favor mineral dissolution) in our phosphate uptake experiments with L. rhamnosus. These results suggest that the localized generation of undersaturated conditions by polyphosphate- accumulating bacteria constitutes a new potential mechanism of tooth dissolution that may augment the effects of metabolic acid production.
Bibliographical noteFunding Information:
We thank Chris Crosby, Thomas Pengo, Dan Jones, Mark Sanders, and Guillermo Marques for training, advice, and assistance. Image acquisition and analysis support was provided by the University of Minnesota Imaging Center. We thank the two anonymous reviewers for their comments that greatly improved the manuscript. Funding for this work was provided by the University of Minnesota Office of the Vice President for Research Minnesota Futures Grant Program. J.V.B., B.E.F., and R.S.J. conceived the study and designed the research with input from A.A.B. Experimental data were generated by A.A.B. with help from J.N. Sample collection was conducted by J.B., M.H., T.R., and R.S.J. Genome research and analysis were conducted by B.E.F. A.A.B. and J.V.B. wrote the paper with input from other authors
© 2018 American Society for Microbiology.
- Dental caries
- Oral biofilms