One of the most common bacteria living in dental plaque is Corynebacterium matruchotii – divides not into two daughter cells, as is usually the case with cell division, but into many new microbes – in a rarer process called mitosis.
A group of scientists led by microbiologist Scott Chimileski of the US Marine Biological Laboratory observed how individual C. matruchotii cells divide into as many as 14 new cells—which may help us learn how these organisms form structures that support other microbes in the mouth.
“Reefs contain coral, forests contain trees, and the plaque in our mouths contains Corynebacterium– explains microbiologist Jessica Mark Welch from ADA Forsyth Institute (USA) and Marine Biology Laboratory. – Those in dental plaque Corynebacterium cells are like a big, bushy tree in a forest. They create a spatial structure that provides a habitat for many other types of bacteria.”
Most bacteria and archaea reproduce through an asexual process called binary fission. The nucleus of one cell that makes up an organism splits into two nuclei, then the cell itself divides, and two organisms appear instead of one.
JM Welch and her colleagues became interested C. matruchotii by reproduction after previous research on thishow plaque bacteria colonies are spatially organized in the biofilm covering human teeth. The dental plaque microbiome forms a spiky “hedgehog”-like structure based on filaments of C. matruchotii.
To observe how these structures fill up with new filaments, the researchers used microscopy to observe in real time how the bacteria in the microbiome interact with each other, coexist, reproduce and grow.
Here they saw that unusual C. matruchotii cell division was not the usual binary, but much more abundant. And that they do it in a very strange way.
First, the filament elongates at only one end, growing much longer than the normal cell size. It does this five times faster than other closely related ones Corynebacterium species living in the nose or on the skin.
Several division walls, called septa, are then formed simultaneously, and only then does the cell divide into 3-14 full-fledged daughter cells.
This strange process allows a colony of C. matruchotii to grow very quickly, up to half a millimeter per day, and this may help explain why plaque starts to return to our teeth within hours, no matter how thoroughly we brush them.
“These biofilms are like microscopic rainforests. Bacteria grow and divide in these biofilms. We think it’s unusual C. matruchotii the cell cycle allows this species to form these very dense networks in the core of the biofilm, says A. Chimileskis. “Something about this very dense, competitive plaque habitat may have encouraged the evolution of this growth pattern.”
Another interesting one C. matruchotii a feature that may account for its strange growth and division is that it lacks the flagella that other bacteria use for locomotion. Because these bacteria are non-motile, their rapid growth could be a means of exploring the environment and searching for food sources, the researchers say.
In this way, the microbe can gain a competitive advantage in the bacteria-filled environment of the human mouth. But scientists have never seen anything like it. It’s a whole new way for bacteria to thrive, and it’s been right here in our own bodies all along.
“We believe that rapid growth by tip extension and simultaneous multiple fission explain how C. matruchotii outperforms other taxa to form filamentous networks in the core of the dental plaque biofilm, the researchers write. “Our findings go beyond the boundaries of the oral microbiome, revealing a unique bacterial cell cycle and an example of how cell morphology and reproductive strategy can influence the spatial organization of microbial communities.”
The findings are published moksliniame žurnale „Proceedings of the National Academy of Sciences“.
Parengta pagal „Science Alert“.
2024-09-05 00:44:35