06 December 2022

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Superorganism found in saliva of kids with tooth decay

Katherine E. Pfaff

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Researchers at the University of Pennsylvania School of Dental Medicine have found a “superorganism” in the saliva of kids with tooth decay. The research suggests the organism is the “cross-kingdom partnership” of fungi and bacteria.

The organism is resilient, more resistant to antimicrobials and more difficult to remove from teeth than either the bacteria or the fungi alone. The organisms were found to be stickier and were tougher to remove from teeth as well, according to a news release. 

“Interkingdom assemblages in human saliva display group-level surface mobility and disease-promoting emergent functions” was published in October 2022 in the Proceedings of the National Academy of Sciences. 

Hyun (Michel) Koo, a professor at Penn Dental Medicine and a corresponding author on the paper, said that the research started with a simple, almost accidental discovery, while looking at saliva samples from toddlers who develop aggressive tooth decay.

The new set of discoveries came about when Zhi Ren, a postdoctoral fellow, was using microscopy that allows scientists to visualize the behavior of living microbes in real time. The technique opens new possibilities to investigate the dynamics of complex biological processes, said Ren, a first author on the paper and a postdoctoral researcher within Penn's Center for Innovation & Precision Dentistry.

Koo said in the release that the bacteria and fungi formed assemblages and developed motions the team never thought they would possess, including walking and leaping.

“It's almost like a new organism — a superorganism — with new functions," he said.

The superorganism also could grow “limbs” that it could use to move around on the surface of teeth, according to the research. The findings could help determine treatments for preventing tooth decay in children.

"If you block this binding or disrupt the assemblage before it arrives on the tooth and causes damage, that could be a preventive strategy,” said Koo.