February 24, 2014
Dental Plaque Bacteria Hasn’t Changed In More Than A Thousand Years
Lawrence LeBlond for redOrbit.com - Your Universe Online
Plaque on the teeth of ancient skeletons dating back 1,000 years have been found to have a wealth of preserved bacteria and microscopic particles of food. An international team of researchers behind the project say this discovery is a “microbial Pompeii” of preservation.
The team, led by researchers from the University of Zurich, the University of Copenhagen and the University of York, and including dozens of researchers from several institutions around the world, discovered that the ancient human oral cavity carries numerous pathogens and that periodontal disease is caused by the same bacteria today as it had in the distant past. This “mineral tomb” of microbiomes confirms that dental calculus, or plaque, has not changed in more than a thousand years, despite changes in diet and hygiene.
As many as eight centuries before the invention of the first therapeutic antibiotics in the 1940s, the human oral microbiome contained the basic genetic machinery for antibiotic resistance, the team further discovered. They were also able to recover dietary DNA from the ancient plaque, allowing them to identify ancient dietary components, such as vegetables, which are otherwise lost in the archaeological record.
Publishing a paper in the journal Nature Genetics, the study authors found that unlike bone, which rapidly loses much of its molecular information after burial, dental plaque enters the soil in a much more stable state helping to preserve biomolecules. This evidence allowed the research team, led by Dr Christina Warinner, of the University of Zurich and University of Oklahoma, to analyze ancient DNA that was not compromised by the burial environment.
Applying shotgun DNA sequencing to the plaque for the first time, the team was able to reconstruct the genome of a major periodontal pathogen and also may have produced the first genetic evidence of dietary biomolecules recovered from ancient plaque. The team acknowledged that they had to overcome significant challenges in bioinformatics to tease out the data from millions of genetic sequences.
"Dental calculus is a window into the past and may well turn out to be one of the best-preserved records of human-associated microbes," study coauthor Professor Christian von Mering, Group Director at the SIB Swiss Institute of Bioinformatics, which performed the bioinformatics analysis, said in a statement.
"We knew that calculus preserved microscopic particles of food and other debris but the level of preservation of biomolecules is remarkable. A microbiome entombed and preserved in a mineral matrix, a microbial Pompeii," said Professor Matthew Collins, of the University of York.
"Dental calculus acts both as a long-term reservoir of the oral microbiome and as a trap for dietary and environmental debris. This allows us to investigate health and disease, as well as reconstruct aspects of an individual's life history and activities. Never before have we been able to retrieve so much information from one small sample," Dr Warinner added.
This study has significant implications for understanding the evolution of the human oral microbiome and the origins of periodontal disease.
Today, moderate to severe periodontal disease affects more than 10 percent of the world’s population and is linked to a series of systemic diseases, such as cardiovascular disease, pulmonary disease and type 2 diabetes. While periodontal disease is common in humans and domestic pets, it does not typically develop in wild animals – zoo animals have been found to develop the disease, however.