Bacteria acquired up to 90 percent of their genetic material from distantly related bacteria species, according to new research from The University of Arizona in Tucson. The finding has important biomedical implications because such gene-swapping, or lateral gene transfer, is the way many pathogenic bacteria pick up antibiotic resistance or become more virulent.

Being able to classify bacteria is crucial for medicine, says Howard Ochman, a UA professor of biochemistry and molecular biophysics and a member of UA’s BIO5 Institute. "If you go to the doctor with strep throat he can be pretty certain that it’s the result of an infection with a species of Streptococcus and can therefore prescribe an appropriate antibiotic. If you couldn’t classify bacteria because they have genes from all over, doctors wouldn’t be able to do this."

Ochman thinks the team’s findings will stir new research in bacterial evolution. "It should be exciting to see whether gene transfer has been so widespread in other groups of bacteria, too."