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Discovery holds promise for decoding elusive bacteria

A new discovery into one bacteria group that has posed a particular challenge for researchers for decades could lead to better understanding of other elusive bacteria.

The bacteria group Candidate Phylum TM7 is thought to cause inflammatory mucosal diseases because it is so prevalent in people with periodontitis, an infection of the gums.

Scientists from the University of California Los Angeles (UCLA), the J. Craig Venter Institute and University of Washington revealed insights into TM7’s resistance to scientific study and to its role in the progression of periodontitis and other diseases.

Their findings shed new light on the biological, ecological and medical importance of TM7.

At left, the tight physical association between TM7x cells and XH001. At right, TM7x cells (red) attach to the surface of XH001 (white).
At left, the tight physical association between TM7x cells and XH001. At right, TM7x cells (red) attach to the surface of XH001 (white).
“This study provides the roadmap for us to make every uncultivable bacterium cultivable,” said Wenyuan Shi, professor of oral biology at UCLA.

The researchers cultivated a specific type of TM7 (TM7x) found in people’s mouths and found the first known proof of a signalling interaction between the bacterium and an infectious agent which causes mucosal inflammation.

“Once the team grew and sequenced TM7x, we could finally piece together how it makes a living in the human body,” added Dr Jeff McLean, acting associate professor at University of Washington’s school of dentistry.

What makes TM7x even more intriguing are its potential roles in chronic inflammation of the digestive tract, vaginal diseases and periodontitis.

The findings were published online in the journal Proceedings of the National Academy of Sciences.

Reference:
Xuesong He, Jeffrey S. McLean, Anna Edlund, Shibu Yooseph, Adam P. Hall, Su-Yang Liu, Pieter C. Dorrestein, Eduardo Esquenazi, Ryan C. Hunter, Genhong Cheng, Karen E. Nelson, Renate Lux, and Wenyuan Shi.Cultivation of a human-associated TM7 phylotype reveals a reduced genome and epibiotic parasitic lifestyle. PNAS 2014 ; published ahead of print December 22, 2014, doi:10.1073/pnas.1419038112

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