“To figure out how all the different kinds of bacteria work together in the plaque biofilm, we have to understand the basic biology of these bacteria, which live nowhere else but the human mouth,” said Mark Welch.
Dentists recommend brushing your teeth (and therefore brushing away dental plaque) twice a day. Yet this biofilm comes back no matter how diligently you brush. By extrapolating from cell elongation experiments measured in micrometers per hour, the scientists found that C. matruchotii colonies could grow up to a half a millimeter per day.
Other species of Corynebacterium are found elsewhere in the human microbiome, such as the skin and inside the nasal cavity. Yet the skin and nasal Corynebacterium species are shorter, rod-shaped cells that aren’t known to elongate by tip extension or divide by multiple fission.
“Something about this very dense, competitive habitat of the dental plaque may have driven the evolution of this way of growing,” said Chimileski.
Exploratory Growth
C. matruchotii lack flagella, the organelles that allow bacteria to move around. Since these bacteria can’t swim, researchers believe its unique elongation and cell division might be a way for it to explore its environment, similar to mycelial networks seen in fungi and Streptomyces bacteria that live in soil.
“If these cells have the ability to move preferentially towards nutrients or towards other species to form beneficial interactions — this could help us understand how the spatial organization of plaque biofilms comes about,” said Chimileski.
“Who would have thought that our familiar mouths would harbor a microbe whose reproductive strategy is virtually unique in the bacterial world,” said co-author Gary Borisy, principal investigator at ADA Forsyth and former director of the Marine Biological Laboratory. "The next challenge is to understand the meaning of this strategy for the health of our mouths and our bodies."
Citation:
Chimileski, Scott., Gary Borisy, Floyd Dewhirst and Jessica Mark Welch (2024). Tip extension and simultaneous multiple fission in a filamentous bacterium, Proceedings of the National Academy of Sciences. DOI: pnas.2408654121
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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.