Dentists identify new bacterial species involved in tooth decay
Large study in children reveals Selenomonas sputigena as a key partner of Streptococcus in cavity formation.

Date:
June 8, 2023
Source:
University of Pennsylvania
Summary:
Large study in children reveals Selenomonas sputigena as a key
partner of Streptococcus in cavity formation.


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FULL STORY ========================================================================== Philadelphia -- Collaborating researchers from the University of
Pennsylvania School of Dental Medicine and the Adams School of Dentistry
and Gillings School of Global Public Health at the University of North
Carolina have discovered that a bacterial species called Selenomonas
sputigena can have a major role in causing tooth decay.

Scientists have long considered another bacterial species, the
plaque-forming, acid-making Streptococcus mutans, as the principal cause
of tooth decay -- also known as dental caries. However, in the study,
which appeared 22 May in Nature Communications, the Penn Dental Medicine
and UNC researchers showed that S.

sputigena, previously associated only with gum disease, can work as a
key partner ofS. mutans, greatly enhancing its cavity-making power.

"This was an unexpected finding that gives us new insights into the
development of caries, highlights potential future targets for cavity prevention, and reveals novel mechanisms of bacterial biofilm formation
that may be relevant in other clinical contexts," said study co-senior
author Hyun (Michel) Koo DDS, PhD, a professor in the Department of Orthodontics and Divisions of Pediatrics and Community Oral Health and Co-Director of the Center for Innovation & Precision Dentistry at Penn
Dental Medicine.

The other two co-senior authors of the study were Kimon Divaris, PhD,
DDS, professor at UNC's Adams School of Dentistry, and Di Wu, PhD,
associate professor at the Adams School and at the UNC Gillings School
of Global Public Health.

"This was a perfect example of collaborative science that couldn't
have been done without the complementary expertise of many groups and individual investigators and trainees," Divaris said.

Caries is considered the most common chronic disease in children and
adults in the U.S. and worldwide. It arises when S. mutans and other acid-making bacteria are insufficiently removed by teeth-brushing and
other oral care methods, and end up forming a protective biofilm, or
"plaque," on teeth. Within plaque, these bacteria consume sugars from
drinks or food, converting them to acids. If the plaque is left in place
for too long, these acids start to erode the enamel of affected teeth,
in time creating cavities.

Scientists in past studies of plaque bacterial contents have identified
a variety of other species in addition to S. mutans. These include
species of Selenomonas, an "anaerobic," non oxygen-requiring group of
bacteria that are more commonly found beneath the gum in cases of gum
disease. But the new study is the first to identify a cavity-causing
role for a specificSelenomonas species.

The UNC researchers took samples of plaque from the teeth of 300 children
aged 3-5 years, half of whom had caries, and, with key assistance
from Koo's laboratory, analyzed the samples using an array of advanced
tests. The tests included sequencing of bacterial gene activity in the
samples, analyses of the biological pathways implied by this bacterial activity, and even direct microscopic imaging. The researchers then
validated their findings on a further set of 116 plaque samples from 3
to 5-year-olds.

The data showed that although S. sputigena is only one of several
caries-linked bacterial species in plaque besides S. mutans, and does
not cause caries on its own, it has a striking ability to partner with
S. mutans to boost the caries process.

S. mutansis known to use available sugar to build sticky constructions
called glucans that are part of the protective plaque environment. The researchers observed that S. sputigena, which possesses small appendages allowing it to move across surfaces, can become trapped by these
glucans. Once trapped, S.

sputigena proliferates rapidly, using its own cells to make
honeycomb-shaped "superstructures" that encapsulate and protect
S. mutans. The result of this unexpected partnership, as the researchers
showed using animal models, is a greatly increased and concentrated
production of acid, which significantly worsens caries severity.

The findings, Koo said, show a more complex microbial interaction than
was thought to occur, and provide a better understanding of how childhood cavities develop -- an understanding that could lead to better ways of preventing cavities.

"Disrupting these protective S. sputigena superstructures using specific enzymes or more precise and effective methods of tooth-brushing could
be one approach," Koo said.

The researchers now plan to study in more detail how this anaerobic
motile bacterium ends up in the aerobic environment of the tooth surface.

"This phenomenon in which a bacterium from one type of environment moves
into a new environment and interacts with the bacteria living there,
building these remarkable superstructures, should be of broad interest
to microbiologists," Koo said.

"Selenomonas sputigena acts as a pathobiont mediating spatial structure
and biofilm virulence in early childhood caries" was co-authored by
Hunyong Cho, Zhi Ren, Kimon Divaris, Jeffrey Roach, Bridget Lin, Chuwen
Liu, M. Andrea Azcarate-Peril, Miguel Simancas-Pallares, Poojan Shrestha,
Alena Orlenko, Jeannie Ginnis, Kari North, Andrea Ferreira Zandona,
Apoena Aguiar Ribeiro, Di Wu and Hyun "Michel" Koo.

The work was funded in part by the National Institutes of Health
(U01DE025046, R01DE025220, R03DE028983).

* RELATED_TOPICS
o Health_&_Medicine
# Dentistry # Diseases_and_Conditions # Medical_Topics #
Children's_Health
o Plants_&_Animals
# Bacteria # New_Species # Microbes_and_More #
Microbiology
* RELATED_TERMS
o Developmental_psychology o Diaphragm_(anatomy) o
Developmental_biology o Central_nervous_system o Middle_ear
o Glutamic_acid o Streptococcus o Radiography

========================================================================== Story Source: Materials provided by University_of_Pennsylvania. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Hunyong Cho, Zhi Ren, Kimon Divaris, Jeffrey Roach, Bridget M. Lin,
Chuwen Liu, M. Andrea Azcarate-Peril, Miguel A. Simancas-Pallares,
Poojan Shrestha, Alena Orlenko, Jeannie Ginnis, Kari E. North,
Andrea G.

Ferreira Zandona, Apoena Aguiar Ribeiro, Di Wu, Hyun
Koo. Selenomonas sputigena acts as a pathobiont mediating spatial
structure and biofilm virulence in early childhood caries. Nature
Communications, 2023; 14 (1) DOI: 10.1038/s41467-023-38346-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/06/230608120924.htm

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