Bad Breath Linked to Chemical from Oral Bacteria Interaction

Bad breath, also known as halitosis, is a common and embarrassing problem that affects millions of people worldwide. It is caused by volatile compounds that are produced when bacteria in the mouth digest substances like blood and food particles. One of the smelliest of these compounds is methyl mercaptan (CH3SH), which is produced by microbes that live around the teeth and on the surface of the tongue. However, little is known about which specific bacterial species are involved in this process.

In this article, we will explore how researchers from Osaka University have recently shed some light on this mystery by revealing that the interaction between two common types of oral bacteria leads to the production of methyl mercaptan. We will also discuss the implications of this finding for the prevention and treatment of bad breath and periodontal disease.

How oral bacteria interact to produce methyl mercaptan

The researchers developed a large-volume anaerobic co-culture system that enabled them to test interactions between multiple different types of bacteria that live in the mouth. This system was able to test both direct, physical interactions among the bacteria, as well as whether these species could affect each other from a distance, for example by secreting active substances.

The results were very intriguing. They found that Fusobacterium nucleatum produces large quantities of methyl mercaptan in response to Streptococcus gordonii, another oral bacterium. By using stable isotope tracers and analyzing gene expression, they showed that S. gordonii releases a substance called ornithine that prompts F. nucleatum to produce more of a molecule called polyamine. Because F. nucleatum needs methionine to produce polyamine, this enhanced polyamine production activates its methionine salvage pathway, which in turn results in increased methyl mercaptan production.

The researchers also confirmed that this interaction occurs in human saliva samples, suggesting that it is relevant for real-life situations. They further demonstrated that inhibiting the ornithine transport or polyamine synthesis in F. nucleatum reduces its methyl mercaptan production, indicating potential targets for intervention.

Why this finding matters for Bad Breath

Taken together, these findings suggest that methyl mercaptan production in the mouth is driven by the interaction between S. gordonii and F. nucleatum. Understanding how these two bacterial species work together to cause bad breath could be helpful in developing ways to treat or even prevent bad breath.

For example, one could use oral hygiene products that contain substances that block the ornithine transport or polyamine synthesis in F. nucleatum, or that reduce the growth or activity of S. gordonii or F. nucleatum. Alternatively, one could use probiotics that introduce beneficial bacteria that compete with or inhibit S. gordonii or F. nucleatum.

In addition, given that bad breath is often associated with periodontal disease, treating this symptom early could help prevent more serious damage in the future. Periodontal disease is a chronic inflammatory condition that affects the gums and bone supporting the teeth, and can lead to tooth loss and increased risk of systemic diseases such as diabetes and cardiovascular disease. By reducing the production of methyl mercaptan and other volatile compounds, one could also reduce the inflammation and infection caused by oral bacteria.

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