To understand the female microbiome even better, we analyzed the saliva of 228 participants during Isala’s second phase. After all, your mouth is teeming with bacteria. Scientific research already showed that there are big differences between distinct locations in your mouth. For example, there are other bacteria on your teeth than on the inside of your cheek. That is precisely why it is so interesting to analyze your saliva, where everything comes together. One millimeter of saliva contains up to 100 million bacteria, more than enough to examine!

Let’s start with a striking observation: thanks to Isala, we learned that every woman’s vagina had a unique combination of bacteria, but for saliva we discovered the near opposite! The salivary microbiome turned out to be very similar between all the participants. We thought that was quite surprising since your saliva actually comes in contact with air all day long, with what you eat and drink and, of course, with the saliva of your eventual partner. However, this does not mean that all these bacteria are also exactly the same, because within genera of bacteria there are still many different species and strains.

Because there are so few differences between the saliva samples, we can say that saliva has a core microbiome or a collection of bacteria that were present in all participants. In microbiology, this refers to the group of bacteria typical of a particular environment. In saliva, it turns out that this core microbiome consists of nine different genera of bacteria that are found in more than 98% of women. So even if you did not participate in this phase of research at Isala, chances are that these bacteria are also in your saliva.

Two genera of bacteria from this core microbiome in saliva you may recognize from the types of bacteria in the vagina, namely Prevotella and Streptococcus. That is not to say that these are completely the same: such a genus of bacteria is like a very large collection and usually contains several more species specifically adapted to a place on your body. For example, Streptococcus salivarius is typically found in saliva (what’s in a name, since saliva is the English translation of saliva), while Streptococcus agalactiae is more likely to be found in the vagina. Unfortunately, with the technology we use at Isala, we cannot always provide a finer picture of exactly which species we found within the different samples. And we do need that for follow-up research in which we want to investigate the function of the different bacteria on our bodies in even greater depth. To be continued!

We hadn’t yet introduced to you the other six typical genera of bacteria we found in the saliva samples: Actinobacillus, Neisseria, Veillonella, Fusobacterium, Gemella and Leptotrichia. If you would like to learn more about these bacteria, you can click on the images below.