Up
to 80 million bacteria sealed with a kiss
As many as 80 million bacteria are transferred during a 10
second kiss, according to research published in the open access journal Microbiome.
The study also found that partners who kiss each other at least nine times a
day share similar communities of oral bacteria.
The ecosystem of more than 100 trillion microorganisms that live
in our bodies -- the microbiome -- is essential for the digestion of food,
synthesizing nutrients, and preventing disease. It is shaped by genetics, diet,
and age, but also the individuals with whom we interact. With the mouth playing
host to more than 700 varieties of bacteria, the oral microbiota also appear to
be influenced by those closest to us.
The results showed that when couples intimately kiss at
relatively high frequencies their salivary microbiota become similar. On
average it was found that at least nine intimate kisses per day led to couples
having significantly shared salivary microbiota.
Lead author Remco Kort, from TNO's Microbiology and Systems
Biology department and adviser to the Micropia museum of microbes, said:
"Intimate kissing involving full tongue contact and saliva exchange
appears to be a courtship behavior unique to humans and is common in over 90%
of known cultures. Interestingly, the current explanations for the function of
intimate kissing in humans include an important role for the microbiota present
in the oral cavity, 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, and it turns out, the
more a couple kiss, the more similar they are."
In a controlled kissing experiment to quantify the transfer of
bacteria, a member of each of the couples had a probiotic drink containing
specific varieties of bacteria including Lactobacillus and Bifidobacteria.
After an intimate kiss, the researchers found that the quantity of probiotic
bacteria in the receiver's saliva rose threefold, and calculated that in total
80 million bacteria would have been transferred during a 10 second kiss.
The study also suggests an important role for other mechanisms
that select oral microbiota, resulting from a shared lifestyle, dietary and
personal care habits, and this is especially the case for microbiota on the
tongue. The researchers found that while tongue microbiota were more similar
among partners than unrelated individuals, their similarity did not change with
more frequent kissing, in contrast to the findings on the saliva microbiota.
Commenting on the kissing questionnaire results, the researchers
say that an interesting but separate finding was that 74% of the men reported
higher intimate kiss frequencies than the women of the same couple. This
resulted in a reported average of ten kisses per day from the males, twice that
of the female reported average of five per day.
To calculate the number of bacteria transferred in a kiss, the
authors relied on average transfer values and a number of assumptions related
to bacterial transfer, the kiss contact surface, and the value for average
saliva volume.
Story
Source:
The above story is based on materials provided by BioMed Central. Note: Materials may be edited for
content and length.
Journal
Reference:
Remco Kort, Martien Caspers, Astrid van de Graaf, Wim van
Egmond, Bart Keijser, Guus Roeselers. Shaping
the oral microbiota through intimate kissing. Microbiome,
2014; 2 (1): 41 DOI: 10.1186/2049-2618-2-41
Cite
This Page:
BioMed Central. "Up to 80 million bacteria sealed with a
kiss." Science Daily,
16 November 2014.
<www.sciencedaily.com/releases/2014/11/141116211033.htm>.
