The more couples kiss, the more bacteria they share – Dutch scientists

Christmas is traditionally a time for kissing under the mistletoe, and with scientists in the Netherlands discovering that 80 million microbes are transferred during a ten-second French kiss, it's a good opportunity for people to improve their exposure to bacteria.

Microbiologists at Micropia in Amsterdam, the world's first museum of microbes, say their "Kiss-O-Meter" has revealed the transfer of microbes is eight times higher than previously thought.

Couples step onto the Kiss-O-Meter, which then measures how many and what type of microbes they exchange during their kiss.

The researchers studied 21 couples, who were also asked to fill in a questionnaire about their kissing behavior.

The results showed that couples have far more similar collections of bacteria with each other than with those with whom they have no relationship.

And according to microbiologist Remco Kort, the more often couples kiss, the greater the transfer of bacteria.

"What we did is we investigated couples before and after kissing and we looked at the collections of bacteria on their tongue and what the research showed is that the couples do have collection of bacteria that is much more similar then when you would compare that to unrelated individuals, So that was one of the conclusions and then what we saw is that after kissing, if we looked at their saliva, we saw that couples that kissed at high frequencies, they had bacteria in their saliva that were more similar than those couples that only kissed a number of times per year," he said.

It was found that couples who averaged nine intimate kisses a day shared similar communities of oral bacteria.

Human beings have more than 100 trillion micro-organisms in their bodies, as part of an ecosystem which is essential for food digestion, synthesizing nutrients and preventing disease. Seven hundred different types of bacteria live in the mouth.

Kort said an experiment in which one member of the couple drank yoghurt containing specific varieties of bacteria allowed the researchers to see how much was transferred during the kiss.

"We invited the couples for a second kiss and asked...for one of the members of the couples to take a yoghurt drink. And then we used the bacteria as indicator and we checked the samples at the Netherlands Organization for Applied Scientific Research where we could do the analysis and identify those collections. And then we saw that there was a slight increase from this indicator bacteria which led us to an estimate, an average estimate of 80 million bacteria transferred per intimate kiss of ten seconds," he said.

But Kort says there is no need to be alarmed by the number of microbes being transferred.

"I think from one point of view you could conclude that kissing is healthy, because kissing is an example of an exposure to a large amount of bacteria and only a minor fraction of them or some of them are able to colonise in the mouth and what you could say is that when you obtain bacteria from your environment or your partner, which leads to an increased diversity, so more species, there are some indication that this is actually good for your health, because you will be able with more species to have more resistance against invasions of disease-causing micro-organisms," he said.

Micropia is exhibiting a collection of living flora and fauna of micro organisms, combined with multimedia presentations and digital images of the invisible world.

Three quarters of all life on Earth is invisible to the naked eye and consists of micro organisms about which almost nothing is known, though without them humans could not survive. They provide the planet with 50 percent of all oxygen and assist in health and digestion. They also have the potential to be used as biofuel, food and medicine. — Reuters