Bad breath really stinks! Now, researchers in Japan report that a particular collection of bacteria in our mouths may be responsible for producing some of the most unpleasant odors.

In a study published last month mSystemsOsaka University researchers revealed that the interaction between two common types of oral bacteria leads to the production of a chemical compound that is a major cause of bad breath.

Bad breath is caused by volatile compounds that are produced when bacteria in the mouth digest substances such as blood and food particles. One of the most malodorous of these compounds is methyl mercaptan (CH3SH), which is produced by microbes living around the teeth and on the surface of the tongue. However, little is known about which specific species of bacteria are involved in this process.

“Most previous studies investigating CH3SH-producing oral bacteria have used isolated enzymes or relatively small culture volumes,” explains Takeshi Hara, lead author of the study.3SH production by major oral bacteria.”

To do this, the researchers developed a large-scale anaerobic co-culture system that enabled them to examine the interactions between many different types of bacteria living in the mouth. The system was able to examine both direct, physical interactions between bacteria, as well as whether these species could influence each other remotely, for example by secreting active substances.

“The results were very interesting,” says Masaye Kabonewa, senior author. “We found it Fusobacterium nucleatum Produces large amounts of CH.3In response to SH Streptococcus gordoniianother oral bacterium.”

Using stable isotope tracers and analyzing gene expression, the researchers showed that S. Gordon Releases a substance called ornithine that signals. F. Nucleatum to produce more of a molecule called polyamine. Because F. Nucleatum Requiring methionine to generate polyamines, this increased polyamine activates its methionine salvage pathway, resulting in increased CH.3Production of SH.

“Taken together, these results suggest that CH3The production of SH in the mouth is stimulated by interactions between S. Gordon And F. Nucleatum” Hara says.

Understanding how these two bacterial species work together to produce bad breath could be helpful in developing ways to treat or prevent bad breath. Also, given that bad breath is often associated with periodontal disease, treating this symptom early can help prevent more serious damage in the future.