Every one of us is different – even when it comes to spit. That’s the conclusion of a new study which says more than 600 microbe species live in our saliva.
According to the Genome Research study, few of these bacteria are shared from person to person.
The human body harbors ten times more bacterial cells than human cells – a stunning figure that suggests a likely dynamic between ourselves and the bacteria we carry, both in healthy and disease states, the study found.
To reach the conclusion, scientists conducted the first in-depth study of global diversity in a human microbiome, characterizing the microbial life in human saliva from regions around the world.
The researchers, led by Dr. Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have sequenced and analyzed variation in the bacterial gene encoding 16S rRNA, a component of the ribosome, in the salivary "metagenome" of 120 healthy subjects from six geographic areas.
Stoneking and colleagues then compared the sequences they found with a database of 16S rRNA sequences to categorize the types of bacteria present.
The group observed that there is considerable diversity of bacterial life in the saliva microbiome, both within and between individuals. However, they made an unexpected finding when comparing samples from different geographic areas.
"The saliva microbiome does not vary substantially around the world," Stoneking described.
"Which seems surprising given the large diversity in diet and other cultural factors that could influence the human salivary microbiome," the expert added.
Stoneking explained that this suggests the life inhabiting the mouth of your next-door neighbor is likely to be just as different from yours as someone on the other side of the world.