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girlwhowaspluggedout writes:

"An international team of researchers has discovered a 'microbial Pompeii'; a menagerie of bacteria and microscopic food particles preserved in the dental plaque of 1000 year old skeletons.

The use of dental plaque for genetic and medical research was described by Professor Christian von Mering, an author of the study and Group Director at the SIB Swiss Institute of Bioinformatics as, 'a window into the past ... [which] may well turn out to be one of the best-preserved records of human-associated microbes.'

The study, published in the latest issue of Nature Genetics (paywalled), focused on four adult human skeletons with evidence of mild to severe gum disease from the medieval (c. 950-1200 CE) monastic site of Dalheim, Germany. Their dental plaque was compared to that of nine living people with known dental histories. By using shotgun DNA sequencing and Raman spectroscopy, the study revealed that although human diet and hygiene have changed considerably during the last millennium, gum disease is caused by the same bacteria today as it had been in the past.

What's more, the research found that the basic genetic machinery for antibiotic resistance had already existed in our oral cavities well before the advent of antibiotics in the 1940s. Thus, the researchers were able to identify native resistance genes to aminoglycosides, Beta-lactams, bacitracin (used in Neosporin), bacteriocins, and macrolides, among others.

The food particles they recovered were preserved well enough to enable DNA analysis, thus identifying some dietary components, such as vegetables, that leave few traces in the archaeological record. Medieval dental plaque was also found to contain disordered carbon (microcharcoal), an environmental pollutant that causes respiratory irritation."