NEW YORK (GenomeWeb) – A study appearing online today in the journal Microbiome looked at the influence "intimate kissing" can have on the human mouth microbiome.
Researchers from the Netherlands used Roche 454 technology to do 16S ribosomal RNA gene sequencing on tongue swab and saliva samples collected from individuals in 21 couples over time.
When they compared the microbial community members found in each person's mouth with their self-reported kissing history, they found that couples tend to have mouth microbiomes that are more similar to one another than to other individuals — particularly at tongue surfaces sampled for the study.
Shared saliva microbiomes were increasingly common within couples confessing to the frequent smooches, though membership in the tongue microbial communities did not seem to shift with more or less frequent kissing.
In a subsequent time course experiment — which involved tracking mouth microbial patterns in kissing couples before and after one of the individuals took a swig of probiotic yogurt drink containing Lactobacillus, Bifidobacterium, and Streptococcus bacteria —the study's authors estimated that some 80 million bacteria get swapped back and forth during a typical 10 second snog, though some of those remain in the saliva only transiently.
"[T]he current explanations for the function of intimate kissing in humans include an important role for the microbiota present in the oral cavity," the study's corresponding author Remco Kort, a researcher affiliated with Micropia museum in Amsterdam and TNO Microbiology and Systems Biology, said in a statement, "although to our knowledge, the exact effects of intimate kissing on the oral microbiota have never been studied.
"We wanted to find out the extent to which partners share their oral microbiota," Kort said, "and it turns out, the more a couple kiss, the more similar they are."