Streptococcus mutans, one of the principal bacteria that cause dental caries, has increased the change in its genetic material over time, possibly coinciding with dietary change linked to the expansion of humanity. This is highlighted in a study by researchers from the Universitat Autnoma de Barcelona (UAB) and the Laboratorio Nacional de Genmica para la Biodiversidad (National Laboratory of Genomics for Biodiversity) in Mexico who, for the first time, have sequenced genetic material from this bacterium in populations from the past. Increase in genetic diversity has been produced especially in the fragment of a gene that codifies a virulence factor known as dextranase.
The research, published in Proceedings of The Royal Society B, has studied the bacterium in eleven individuals from the Bronze Age up to the twentieth century, in Europe and in both pre- and post-colonial America. The oldest case is that of an individual dating from 1200 BC, from the burial cave in Montanisell (Lleida, Catalonia); the most recent, from the UAB collection, dates from the beginning of the twentieth century.
"The relationship is well known between the increase in frequency of caries and the dietary changes that occurred in the Neolithic, or with the European discovery of America, with the large-scale introduction of sugarcane to Europe, or the Industrial Revolution, but what was not known was whether this change happened jointly with changes at a genetic level is this bacterium", explains Marc Simn, trainee researcher in the UAB Biodiversity doctorate and the article's principal author.
"We saw that, in the most recent populations, genetic diversity was greater; to us, this indicates a population-based expansion by the bacterium that may have occurred in parallel with the demographic expansion of humans. We think that this increase took place in the Neolithic. Currently, the oldest individual we have analysed is from the Bronze Age
|Contact: Maria Jesus Delgado|
Universitat Autonoma de Barcelona