The oral microbiome-the sum total of microorganisms, including bacteria and fungi, that inhabit the human mouth,was the subject of a crowd-sourced, citizen science-driven study by Jessica Metcalf’s research laboratory at CSU and Nicole Garneau’s research team at the Denver Museum of Nature & Science. The study, reported in Scientific Reports, found a correlation between people who did not frequently visit the dentist and increased the prevalence of a pathogen that causes periodontal disease.
A large cross-section of museum guests submitted to a cheek swab and answered simple questions about their backgrounds, behaviors and health habits for the experiments conducted by Garneau’s group science team at the museum’s Taste Lab Genetics. Microbial DNA sequencing data analyzed by Metcalf’s group widely showed that bacterial populations in the mouth are influenced by oral health habits. The research highlighted the need to think about oral health as being strongly linked to the whole body’s wellbeing.
“Our study also showed that crowdsourcing and using community scientists can be a really good way to get this type of data, without having to use large, case-controlled studies,” said Zach Burcham, a postdoctoral researcher and the paper’s lead author.
Senior author Metcalf is an associate professor in the Department of Animal Sciences and a member of CSU’s Microbiome Network.
Back in 2015, paper-co-author Garneau and her team taught volunteer citizen scientists to use large swabs to gather museum visitors ‘ cheek cells— a naturally diverse population— who consented to the report. Such professional citizen scientists helped collect swabs from 366 people— 181 adults and 185 youths aged 8 to 17.
The original motivation for the research was to decide if the oral microbiome leads to the way people taste sweet things, and to what degree. The researchers noted more significant data points about oral health practices while gathering this data which was also recorded in the paper.
Garneau has turned to Metcalf’s team of experts at CSU to help translate the results. To establish which microbes were present in which mouths, Burcham and the microbiome scientists employed sophisticated sequencing and analysis tools. Sequencing for the data was carried out in conjunction with scientists at the University of California San Diego community of Rob Knight. A nutrition team from Michigan State University has also brought experience to the data analysis on the value of infant and maternal relationships.
“Together, we had a dream team for using community science to answer complicated questions about human health and nutrition, using state-of-the-art microbial sequencing and analysis,” Garneau said.
FLOSSING AND REGULAR DENTAL CARE
The survey categorized people who either flossed or didn’t floss (nearly everyone said they brushed, so that wasn’t a useful data point). Participants who flossed in their mouths were found to have greater microbial diversity than non-flossers. This is most likely because of the physical removal of bacteria that could cause inflammation or disease.
Adults who had been to a dentist in the past three months had lower overall microbial diversity in their mouths than those who had not gone in 12 months or longer, and had less of the parodontal oral pathogen, Treponema.
This, again, was probably due to dental cleaning in the mouth which removed rarer bacterial taxa. More recently, teenagers appeared to have had dental visits than adults.
Microbiomas of young people varied between males and females, and by weight. Children considered obese by their body mass indices had distinct microbiomes compared with children who were not obese. The obese kids also appeared to have higher levels of Treponema, the same pathogen found in adults who hadn’t been to the dentist in over a year. In other words, the researchers have seen a possible link between obesity in childhood and parodontal disease.
“This was very interesting to me, that we were able to detect these data in such a general population, with such a variable group of people,” Burcham said.
Other data uncovered: Younger participants ‘ microbiomes, mostly in the 8-to 9-year-old range, were more diverse than adults’. Adult microbiomes, however, ranged wider from person to person. The researchers think this is because of more wide-ranging adult environments and diets than adolescents.
They also saw humans living in the same household sharing similar oral microbiomes.
“When you look at families who live together, you find they share more of those rare taxa, the bacteria that aren’t found as often in higher abundances,” Burcham explained. It was a data point that underscored the relevance of one’s built environment in relationship to the microbial communities in our bodies.
Working on the study of mouth was fascinating, albeit outside the normal scope of Burcham; he is usually focused on studying decomposition microbial ecology.
“I think how our lives are essentially driven by our microbiomes, and affected by our microbiomes, is interesting, no matter what system we’re looking at,” Burcham said.
The study was made possible by a Science Education Partnership Award from the National Institute of General Medical Sciences, National Institutes of Health (Award #R250D021909).