I had a microbiology professor in medical school who told me something I’ll never forget. He said if you kiss somebody, you will carry around the microbial evidence of that kiss forever.

We know there are some 500 different species of bacteria in the mouth, which researchers can determine by growing a culture of a mouth swab in a laboratory petri dish.

Well, it turns out some germs don’t grow well under laboratory conditions but they can be detected by DNA technology, and guess what? There are a lot more germs in our mouths than previously believed, including some previously unknown to science, according to a report by Stanford University researchers.

The researchers say 37 unique bacteria were found in a swab sample of the subgingival crevice – the deep gum pocket cradling each tooth. This is an area that may be rich in other unknown microbes, according to the study published in the Proceedings of the National Academy of Science.

Remember, the human mouth is awash in bacteria, mostly the friendly variety that help us to digest food and fight off dangerous disease-causing germs. Finding exactly what germs are in our mouth and gums helps researchers to understand changes in bacterial populations that lead to such things as gingivitis, periodontitis and tooth decay.

What this study indicates is you may be carrying bacteria from almost anything your mouth ever touched – including all those romantic kisses. Think of that next time you kiss someone goodnight.