Cellular elongation at the tips of the filamentous bacteria Corynebacterium matruchotii.
Credit: Chimileski et al (2024).
But the trick a bacterium, Corynebacterium matruchotii, that is only found in the human mouth uses is to divide into multiple new cells at each generation. For example, assuming it splits into 10 daughter cell at each generation, its growth rate from a single founder cell will be 1 → 10 → 100 → 1000 → 10,000 → 100,000 → 1,000,000 … etc., (population = 10n). But scientists have found it can do better than that, producing up to 14 new cells at each generation.
In 6 generations in favourable conditions, Corynebacterium matruchotii can produce 1 million or more offspring, against an 'ordinary' bacteria's 64, so rapidly out-pacing any other bacteria. C. matruchotii is an essential component of the plaque that quickly develops on teeth. It appears to have no other known function.
In some ways, C. matruchotii behaves more like fungal hyphae, growing at the tip to produce a long thin filament. It is this filament that then simply splits up into small sections, each of which becomes a new cell.
The filamentous bacteria C. matruchotii splitting into multiple cells at once, a rare kind of cell division called multiple fission.
Credit: Scott Chimileski, MBL
This latest discovery shows how the beginnings of this organised colony are established very quickly.
What information do you have on the bacterium Corynebacterium matruchotii? Corynebacterium matruchotii is a Gram-positive, non-motile, rod-shaped bacterium that is part of the Corynebacterium genus. Here is a summary of key information about this bacterium:The scientists think this method of rapid growth helps lay down the foundation of the biofilm on our teeth that will quickly build up to form plaque, predisposing us to dental caries, and, if allowed to proliferate, to other problems such as gingivitis and tooth-loss.
- Classification and Morphology
- Domain: Bacteria
- Phylum: Actinobacteria
- Class: Actinobacteria
- Order: Corynebacteriales
- Family: Corynebacteriaceae
- Genus: Corynebacterium
- Species: Corynebacterium matruchotii
- Morphological Characteristics
- Shape: Rod-shaped, often described as pleomorphic (can change shape).
- Gram Stain: Gram-positive.
- Motility: Non-motile.
- Oxygen Requirement: Facultative anaerobe (can survive with or without oxygen).
- Special Structures: Notable for having "whip-like filaments" called fibrils that extend from its cell wall.
- Habitat and Ecology
- Natural Habitat: Commonly found in the human oral cavity, particularly in dental plaque and on the surface of teeth.
- Ecological Role: It is involved in the formation of dental plaque and contributes to the microbial community dynamics within the oral cavity.
- Interactions: Plays a role in the development and maturation of dental plaque. C. matruchotii interacts with other oral bacteria, including Streptococcus species, in biofilm formation.
- Pathogenic Potential
- Pathogenicity: Generally considered a commensal organism in the oral cavity and not known to be highly pathogenic. However, it can contribute to the buildup of dental plaque and potentially to oral diseases such as gingivitis or periodontitis if conditions allow overgrowth or dysbiosis (an imbalance in the microbial community).
- Notable Characteristics and Research Interest
- Unique Fibrils: The presence of whip-like filaments (fibrils) extending from its cell wall is of particular interest to researchers. These fibrils are thought to help in the adhesion to surfaces, including teeth and other bacterial cells, facilitating the formation of dental plaque.
- Role in Oral Biofilm: C. matruchotii is known to be one of the initial colonizers of the dental surface and may play a critical role in the structure and stability of the biofilm. Its interaction with other species, such as Fusobacterium nucleatum, is essential for the maturation and pathogenicity of dental plaque.
- Clinical Relevance
- Dental Plaque Formation: Due to its role in dental plaque formation, it is studied in the context of oral hygiene and dental health. Its presence in biofilms makes it a target for strategies aimed at disrupting plaque formation and preventing tooth decay or gum disease.
- Research Insights
- Biofilm Formation Studies: Studies focus on understanding how C. matruchotii adheres to teeth and other bacteria, and how its presence influences the overall microbial community structure in the oral cavity.
- Potential as a Marker for Oral Health: Its abundance or activity levels may be studied as a biomarker for specific oral health conditions, given its integral role in biofilm formation and its interactions with other microbial species.
Would you like more detailed information on any specific aspect of Corynebacterium matruchotii?
The discovery of this rare form of cell reproduction is the subject of a paper in Proceedings of the National Academy of Sciences by scientists from the Marine Biological Laboratory (MBL) of the University of Chicago, and the American Dental Association Forsyth Institute (ADA Forsyth), and a news release from MBL, Chicago:
Open Wide: Human Mouth Bacteria Reproduce through Rare Form of Cell Division
One of the most diverse ecosystems on the planet is closer than you think — right inside your mouth. Your mouth is a thriving ecosystem of more than 500 different species of bacteria living in distinct, structured communities called biofilms. Nearly all of these bacteria grow by splitting [or dividing] into two, with one mother cell giving rise to two daughter cells.
New research from the Marine Biological Laboratory (MBL) and the American Dental Association Forsyth Institute (ADA Forsyth) uncovered an extraordinary mechanism of cell division in Corynebacterium matruchotii, one of the most common bacteria living in dental plaque. The filamentous bacterium doesn’t just divide, it splits into multiple cells at once, a rare process called multiple fission. The research is published this week in Proceedings of the National Academy of Sciences. The team observed C. matruchotii cells dividing into up to 14 different cells at once, depending on the length of the original mother cell. These cells also only grow at one pole of the mother filament—something called “tip extension.”
C. matruchotii filaments act as a scaffolding within dental plaque, which is a biofilm. Dental plaque is just one microbial community within an immense population of microorganisms that live in and coexist with a healthy human body—an environment known as the “human microbiome.” This discovery sheds light on how these bacteria proliferate, compete for resources with other bacteria, and maintain their structural integrity within the intricate environment of dental plaque.
Reefs have coral, forests have trees, and the dental plaque in our mouths has Corynebacterium. The Corynebacterium cells in dental plaque are like a big, bushy tree in the forest; they create a spatial structure that provides the habitat for many other species of bacteria around them>
Jessica Mark Welch, co-corresponding author
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution
Marine Biological Laboratory, Woods Hole, MA, USA
And Department of Microbiology,
American Dental Association Forsyth Institute, Cambridge, MA, USA.
These biofilms are like microscopic rainforests. The bacteria in these biofilms interact as they grow and divide. We think that the unusual C. matruchotii cell cycle enables this species to form these very dense networks at the core of the biofilm.
Scott Chimileski, lead author on the paper.
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution
Marine Biological Laboratory, Woods Hole, MA, USA.
The Microbial Forest This research builds off of a 2016 paper that used an imaging technique developed at the MBL called CLASI-FISH (combinatorial labeling and spectral imaging fluorescent in situ hybridization) to visualize the spatial organization of dental plaque collected from healthy donors. This earlier study imaged bacterial consortia within dental plaque, which are called “hedgehogs” due to their appearance. One of the major findings from that original paper was that filamentous C. matruchotii cells acted as the basis of the hedgehog structure.
A “hedgehog” structure in dental plaque, collected from a healthy volunteer using a toothpick. Corynebacteria, shown in magenta, form the core of the structure; other bacteria inhabit the structure at characteristic positions.Photo credit: Jessica Mark Welch, MBL
A colony of Corynebacterium matruchotii.Credit: Scott Chimileski, MBL
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.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.
Jessica L. Mark Welch
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.
Scott 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.
,Scott Chimileski.Who would have thought that our familiar mouths would harbor a microbe whose reproductive strategy is virtually unique in the bacterial world. The next challenge is to understand the meaning of this strategy for the health of our mouths and our bodies.
Gary Borisy, co-corresponding
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution
Marine Biological Laboratory, Woods Hole, MA, USA
And Department of Microbiology
American Dental Association Forsyth Institute, Cambridge, MA, USA.
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
SignificanceLet's first of all dispense with the traditional creationist excuse for these harmful pathogens of blaming 'Sin', 'genetic entropy' and the even more ludicrously nonsensical 'devolution', as 'genetic entropy' causes genes to degenerate from their initial created perfection. Anything which benefits an organism can't logically be described as less perfect than what preceded it so can't be waved aside a 'devolutionary'. It is classically evolutionary, regardless of what Michael J. Behe, of the Deception Institute, calls it.
The shape of bacterial cells and the way that bacteria maintain their shape through cellular reproduction are fundamental biological characteristics that link form, physiology, and environment in the microbial world. While most bacteria divide by binary fission, we found a remarkable example of simultaneous multiple fission in a filamentous bacterium that has a key structural role within human dental plaque. This study expands our understanding of the oral microbiome, where hundreds of bacterial species compete for space and nutrients, forming biofilms that have direct impacts on human health. And our findings extend beyond 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.
Abstract
Organisms display an immense variety of shapes, sizes, and reproductive strategies. At microscopic scales, bacterial cell morphology and growth dynamics are adaptive traits that influence the spatial organization of microbial communities. In one such community—the human dental plaque biofilm—a network of filamentous Corynebacterium matruchotii cells forms the core of bacterial consortia known as hedgehogs, but the processes that generate these structures are unclear. Here, using live-cell time-lapse microscopy and fluorescent D-amino acids to track peptidoglycan biosynthesis, we report an extraordinary example of simultaneous multiple division within the domain Bacteria. We show that C. matruchotii cells elongate at one pole through tip extension, similar to the growth strategy of soil-dwelling Streptomyces bacteria. Filaments elongate rapidly, at rates more than five times greater than other closely related bacterial species. Following elongation, many septa form simultaneously, and each cell divides into 3 to 14 daughter cells, depending on the length of the mother filament. The daughter cells then nucleate outgrowth of new thinner vegetative filaments, generating the classic “whip handle” morphology of this taxon. Our results expand the known diversity of bacterial cell cycles and help explain how this filamentous bacterium can compete for space, access nutrients, and form important interspecies interactions within dental plaque.
Chimileski, Scott; Borisy, Gary G.; Dewhirst, Floyd E.; Mark Welch, Jessica L.
Tip extension and simultaneous multiple fission in a filamentous bacterium
Proceedings of the National Academy of Sciences 121(37) e2408654121, DOI: 10.1073/pnas.2408654121
© 2024 PNAS.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
But, in rejecting that explanation, creationists are left with their notion of intelligent design to explain these observations - in other words, these bacteria, which are unique to the human mouth, have been intelligently designed for the single purpose of producing dental plaque and assisting S. mutans in creating dental caries, and other bacteria to cause gum disease end tooth loss, because that is all they do and they are good at doing it.
So, we again have the age-old, unresolved paradox for intelligent [sic] design advocates: malevolent design, or mindless, natural evolution?
The Malevolent Designer: Why Nature's God is Not Good
This book presents the reader with multiple examples of why, even if we accept Creationism's putative intelligent designer, any such entity can only be regarded as malevolent, designing ever-more ingenious ways to make life difficult for living things, including humans, for no other reason than the sheer pleasure of doing so. This putative creator has also given other creatures much better things like immune systems, eyesight and ability to regenerate limbs that it could have given to all its creation, including humans, but chose not to. This book will leave creationists with the dilemma of explaining why evolution by natural selection is the only plausible explanation for so many nasty little parasites that doesn't leave their creator looking like an ingenious, sadistic, misanthropic, malevolence finding ever more ways to increase pain and suffering in the world, and not the omnibenevolent, maximally good god that Creationists of all Abrahamic religions believe created everything. As with a previous book by this author, "The Unintelligent Designer: Refuting the Intelligent Design Hoax", this book comprehensively refutes any notion of intelligent design by anything resembling a loving, intelligent and maximally good god. Such evil could not exist in a universe created by such a god. Evil exists, therefore a maximally good, all-knowing, all-loving god does not.
Illustrated by Catherine Webber-Hounslow.
Available in Hardcover, Paperback or ebook for Kindle
Illustrated by Catherine Webber-Hounslow.
The Unintelligent Designer: Refuting The Intelligent Design Hoax
ID is not a problem for science; rather science is a problem for ID. This book shows why. It exposes the fallacy of Intelligent Design by showing that, when examined in detail, biological systems are anything but intelligently designed. They show no signs of a plan and are quite ludicrously complex for whatever can be described as a purpose. The Intelligent Design movement relies on almost total ignorance of biological science and seemingly limitless credulity in its target marks. Its only real appeal appears to be to those who find science too difficult or too much trouble to learn yet want their opinions to be regarded as at least as important as those of scientists and experts in their fields.
Available in Hardcover, Paperback or ebook for Kindle
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