Study reveals ability of microbes to leap across dental surfaces

A study by a research team out of the University of Pennsylvania has discovered that what it terms as “multicellular, cross-kingdom assemblages “ of bacteria and fungi newly emergent groupings of bacteria can “leap” more than two times their own body length across teeth, explaining how it is that they are able to so rapidly colonise dental surfaces and give rise to dental caries.

Reported by Dental Tribune, the study revealed that these assemblages, found in the saliva of toddlers with severe childhood tooth decay, are "stickier, more resistant to antimicrobials, and more difficult to remove from teeth than either the bacteria or the fungi alone".

Their speed of movement is the result of their unexpected ability to sprout “limbs” that allow them to in effect “walk” or “leap” almost 200 times their body length, a remarkable ability given that the constituent microbes are, on their own, non-motile.

Hyun (Michel) Koo, a professor at Penn Dental Medicine and a co-corresponding author on the paper explains further.

“This started with a very simple, almost accidental discovery, while looking at saliva samples from toddlers who develop aggressive tooth decay. Looking under the microscope, we noticed the bacteria and fungi forming these assemblages and developing motions we never thought they would possess: a ‘walking-like’ and ‘leaping-like’ mobility. They have a lot of what we call ‘emergent functions’ that bring new benefits to this assemblage that they could not achieve on their own. It’s almost like a new organism—a superorganism—with new functions.”

The observation by a member of Koo’s team, Zhi Ren says the microscopy used to observe the behaviour of these assemblages “opens new possibilities to investigate the dynamics of complex biological processes" and specifically in the case of this study, was used "observe the process of attachment and eventual growth ... [in] the bacterial-fungal clusters present in the saliva samples".

While the exact mechanisms behind this activity are yet to be determined, understanding that the assemblages “move as they grow” provides enhanced understanding of how they so quickly colonise dental surfaces, a discovery which could lead to a preventive strategy to stop the assemblages from arriving on the teeth and causing damage.

For the full media release from the University of Pennsylvania, visit "Microbes that cause cavities can form superorganisms able to ‘crawl’ and spread on teeth"