They discovered that the Black Death that devastated Europe between 1347 and 1350 was likely close to the common ancestor of all extant Y. pestis strains, (which likely arose — from the soil bacterium
Yersinia pseudotuberculosis — between 1200 and 1340).
«Yersinia pestis is actually a specific mutant lineage of the bacterium
Y. pseudotuberculosis, which is found in soil,» co-author Alexander Herbig of the Max Planck Institute for the Science of Human History told Seeker.
The symptoms of tularemia are similar to the symptoms of other bacterial diseases such
as pseudotuberculosis and plague, so a definitive diagnosis requires the bacterium to be identified by either culture or by antibody testing.
Using the same samples, the team also traced the evolution of Y. pestis and confirmed that it evolved from a soil bacteria closely related to Yersinia
pseudotuberculosis, a bacterium that causes Far East scarletlike fever in humans, and is most often spread through food.
Yersinia pestis, the bacterium that causes plague, probably descended from Yersinia
pseudotuberculosis, one of a group of relatively benign intestinal diseases.
Yersinia
pseudotuberculosis and many similar bacteria infect humans by injecting toxins, so - called effector proteins, through a needle - like organelle called injectisome.
The researchers can now show that two proteins that bind to one another slow down a chemical reaction central to the course of the disease in the bacteria Yersinia
pseudotuberculosis.