Scientists have pieced together sections of DNA from 12 individual cells to sequence the genome of a bacterium known to live in healthy human mouths.
With this new data about a part of the body considered “biological dark matter,” the researchers were able to reinforce a theory that genes in a closely related bacterium could be culprits in its ability to cause severe gum disease.
Why the dark matter reference? More than 60 percent of bacteria in the human mouth refuse to grow in a laboratory dish, meaning they have never been classified, named or studied. The newly sequenced bacterium, Tannerella BU063, is among those that to date have not successfully been grown in culture – and its genome is identified as “most wanted” by the Human Microbiome Project.
The federal Human Microbiome Project aims to improve research about the microbes that play a role in health and disease. Those 12 cells of BU063 are a good example of the complexity of life in the mouth: They came from a single healthy person but represented eight different strains of the bacterium.
BU063 is closely related to the pathogen Tannerella forsythia, a bacterium linked to the gum disease periodontitis. Despite being “cousins,” this research revealed that they have clear differences in their genetic makeup.
Those genes lacking in BU063 but present in forsythia – meaning they are a likely secret behind forsythia’s virulence – are now identified as good targets for further study, researchers say.
“One of the tantalizing things about this study was the ability to do random searches of other bacteria whose levels are higher in periodontitis,” said Clifford Beall, research assistant professor of oral biology at The Ohio State University and lead author of the study. “We looked for genes that were present in these bacteria and forsythia and not in BU063. There is one particular gene complex in a whole list of these periodontitis-related bacteria that could be involved with virulence.”
The research is published in the journal PLOS ONE.
Periodontitis results when extensive inflammation or infection of the gums spreads beyond the gums to damage structures that support the teeth, including bone. Pockets that form between the gums and teeth are filled with different kinds of bacteria. Treatment typically involves deep cleaning or surgery to remove these infected pockets. Because multiple bacteria are associated with the disease, antibiotics have not been considered effective for treatment.
And though many bacteria in these pockets have been collected and at least partially identified, their characteristics remain a mystery.
“We think some of the gene differences we’ve found in this study are important, but it’s still not clear what all these genes do, meaning we still don’t know why certain bacteria in periodontitis are pathogenic in the first place. Basically the circumstances surrounding periodontitis aren’t very well understood,” Beall said.
“There are a lot of different bacteria that are higher in periodontitis lesions, but we don’t see every one of those bacteria in every case of periodontitis. So it’s hard to see a drug affecting one bacteria being very successful.”
Beall’s colleagues at the Oak Ridge National Laboratory collected a sample of oral material from under the gums of a single healthy person for this study. There, researchers sorted out 12 single BU063 bacterial cells and created extra copies of each cell’s DNA before sending them to Beall at Ohio State.
Beall sequenced the genomes of all 12 cells and, using genome segments from single or groups of cells, constructed an entire genome for BU063.
Completing that genome was a feat in itself, but the larger purpose was learning more about forsythia, he noted. This pathogenic bacterium can be grown in the lab and tested against mammal and human cells, but the reason behind its virulence hasn’t been confirmed.
The scientists discovered that while BU063’s genome is more similar to forsythia’s than any other known genome, the two have a 44 percent difference in gene content.
This research also supported an existing theory that three genes could be related to forsythia’s ability to cause disease because these genes are missing from BU063. Two have potential to damage tissue and inactivate the immune response and the third is a cell-surface molecule that interacts with human cells.
In a comparison with additional organisms linked to chronic periodontitis, Beall also identified a gene cluster present in forsythia and these other pathogens that is missing from the BU063 genome.
The findings contribute to the Human Microbiome Project, which initially focused on characterizing microbial communities in the mouth as well as other areas of the body.
Beall noted that he was surprised to find that the 12 cells from a single mouth represented eight different strains of the BU063 species of bacteria.
“We expect people to have 150 to 200 species of bacteria in their mouths, but they may have all these layers underneath of 20 little variants – at least it’s a possibility based on this organism,” he said. “This may go to show that our microbiome is even more complicated than we’ve previously thought.”
The research was supported by the National Institute of Dental and Craniofacial Research and the National Human Genome Research Institute.
Co-authors include Daniel Dayeh and Eugene Leys of oral biology and Ann Griffen of pediatric dentistry and community oral health, all in Ohio State’s College of Dentistry, and Alisha Campbell (now at Northwest Missouri State University) and Mircea Podar of Oak Ridge National Laboratory and the University of Tennessee.
Contact: Clifford Beall, (614) 292-9306; Beall.firstname.lastname@example.org
Emily Caldwell | Newswise
New mechanisms uncovered explaining frost tolerance in plants
26.09.2016 | Technische Universität München
Chains of nanogold – forged with atomic precision
23.09.2016 | Suomen Akatemia (Academy of Finland)
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.
In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...
Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.
K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...
23.09.2016 | Event News
20.09.2016 | Event News
16.09.2016 | Event News
26.09.2016 | Physics and Astronomy
26.09.2016 | Physics and Astronomy
26.09.2016 | Life Sciences