European researchers have recovered a genome of the bacterium Brucella melitensis from a 700-year-old skeleton found in the ruins of a Medieval Italian village.
Reporting this week in mBio, the online open-access journal of the American Society for Microbiology, the authors describe using a technique called shotgun metagenomics to sequence DNA from a calcified nodule in the pelvic region of a middle-aged male skeleton excavated from the settlement of Geridu in Sardinia, an island off the coast of Italy. Geridu is thought to have been abandoned in the late 14th century. Shotgun metagenomics allows scientists to sequence DNA without looking for a specific target.
From this sample, the researchers recovered the genome of Brucella melitensis, which causes an infection called brucellosis in livestock and humans. In humans, brucellosis is usually acquired by ingesting unpasteurized dairy products or from direct contact with infected animals. Symptoms include fevers, arthritis and swelling of the heart and liver. The disease is still found in the Mediterranean region.
"Normally when you think of calcified material in human or animal remains you think about tuberculosis, because that's the most common infection that leads to calcification," says senior study author Mark Pallen, PhD, professor of microbial genomics at Warwick Medical School in Coventry, England. "We were a bit surprised to get Brucella instead."
The skeleton contained 32 hardened nodules the size of a penny in the pelvic area, though Pallen says it's unclear if they originated in the pelvis, or higher up in the chest or other body part.
In additional experiments, the research team showed that the DNA fragments extracted had the appearance of aged DNA they were shorter than contemporary strands, and had characteristic mutations at the ends. They also found that the medieval Brucella strain, which they called Geridu-1, was c
|Contact: Jim Sliwa|
American Society for Microbiology