A new study published online on in the latest journal Microbiome said a 10-second kiss can transfer 80 million bacteria into partner's mouth.

People’s mouth plays host to 700 varieties of bacteria, which are part of an ecosystem of bacteria, or microbiome, that help digest and break down food.

Remco Kort, lead author of the study, a microbiologist at the Netherlands Organization for Applied Scientific Research, said the couples that kiss intimately at least nine times a day "involving full tongue contact and saliva exchange" significantly share salivary microbiota.

Researchers in the Netherlands had 21 couples visiting a zoo in Amsterdam asked to lock lips for 10 seconds. Before the kiss, one member of each couple drank a yogurt drink containing specific strains of bacteria.

After the kiss, the researchers swabbed the mouth of the partner who hadn't drunk the yogurt and count the numbers of bacteria. The 21 couples also answered questions about their kissing habits.

Media review on Thursday said, boosting bacteria could be a good thing, as they cited the researchers as saying, "If you increase the diversity of good bacteria, you can increase resistance against infection."