Research discovers role of previously uncultivable bacteria in oral disease
SEATTLE & LOS ANGELES, USA: According to biology experts, there are ten times more bacterial cells living in the human body than human cells. However, it is estimated that half of these bacteria are very difficult to replicate and they have thus not been researched in detail. Now, a new study has provided insights into bacterial resistance and the role of these uncultivable bacteria in the progression of periodontitis and other diseases.
The researchers looked at the candidate phylum TM7 in particular, which is globally distributed and often associated with human inflammatory mucosal disease. Despite its prevalence, the bacteria have remained recalcitrant to cultivation, making it one of the most enigmatic phyla known, referred to as "microbial dark matter," the researchers said.
In the study, however, they were able to cultivate TM7x, a specific type of TM7 that can be found in the human oral cavity, and found proof of a signaling interaction between the bacterium and Actinomyces odontolyticus (XH001), an infectious agent that causes mucosal inflammation.
This may be the first example of a parasitic long-term attachment between two different bacteria—where one species lives on the surface of another species gaining essential nutrients and then killing its host, explained Dr. Jeffrey S. McLean, an associate professor at the University of Washington.
"I consider this the most exciting discovery in my 30-year career," said Dr. Wenyuan Shi, professor of biology at the University of California, Los Angeles. "The study provides the roadmap for us to make every uncultivable bacterium cultivable," Shin concluded.
In addition, the researchers examined the degree to which TM7x contributes towards chronic inflammation, such as periodontitis, and observed that inflammation was greatly reduced when TM7x was physically attached to XH001.
Currently, plans are underway to further investigate the relationship between TM7x and XH001 and how they jointly cause mucosal disease. This research could have important implications for potential dental treatment and therapy.
The study, titled "Cultivation of a Human-Associated TM7 Phylotype Reveals a Reduced Genome and Epibiotic Parasitic Lifestyle," was published in the December issue of the Proceedings of the National Academy of Sciences of the United States of America journal.