Plaque results from various bacteria building up on the teeth, though how these communities are organized has been unknown. Using a new imaging approach and sequencing data from the Human Microbiome Project, researchers have proposed a model for how they form.
Dental plaque contains microscaled “hedgehog” structures in which 8 kinds of bacteria are radially arranged around a ninth, filamentous Corynebacteria. These structures give scientists valuable information about how the bacterial members function.
“Microbes behave very differently depending on where they are and who they are next to,” said Jessica Mark Welch of the Marine Biological Laboratory in Woods Hole, Mass, and leader of the study.
“They will secrete entirely different sets of chemicals and metabolites depending on who their microbial neighbors are. So, if we want to accurately describe what these microbes are doing—really, what they are—we need to know where they are,” Mark Welch said.
Spectral imaging fluorescence in situ hybridization guided by metagenomic sequence analysis revealed the bacterial structure. Anaerobic taxa tend to be in the interior, for example, and facultative or obligate aerobes tend to be at the periphery. Also, consumers and producers of metabolites such as lactate tend to be near each other.
“The degree of organization we found in the hedgehog structure was amazing, as was the repeated finding of the same structure in different individuals,” said Mark Welch. “This finding that bacteria can develop such a degree of spatial organization may be generalizable to other microbiomes. We just have to go look.”
The study, “Biogeography of a Human Oral Microbiome at the Micron Scale,” was published by the Proceedings of the National Academy of Sciences of the United States of America.
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