OCT 09, 2019 5:12 PM PDT

A Bacterial Pathogen Can Steal Huge Chunks of DNA From Other Microbes

WRITTEN BY: Carmen Leitch

Microorganisms are everywhere, and they are often engaged in a fight for resources with other microbes. They can adapt to changing conditions and have many specialized abilities. The bacterium that causes cholera, Vibrio cholerae, has a kind of miniature spear and can stab other microbes with it. Called the type VI secretion system (T6SS), it was discovered in 2015 by scientists at the Ecole Polytechnique Fédérale de Lausanne (EPFL) led by Melanie Blokesch.  Bacteria can also easily share genes with each in a process called horizontal gene transfer; it’s one of the ways that resistance to antibiotics is spread, for example. The researchers have now found that the T6SS enables V. cholerae to grab genes from the bacteria they poke.

Under a high magnification of 22371X, this scanning electron microscopic (SEM) image depicted a Vibrio cholerae bacterium of the serogroup 01. / Credit: CDC/ Janice Haney Carr

Reporting in eLife, Blokesch's team determined that the V. cholerae bacterium, which has been responsible for seven serious outbreaks since 1817 and still causes the deaths of over 100,000 people every year, can steal a huge amount of genetic material with its spear. By sequencing the genomes of nearly 400 strains of V. cholerae, the researchers found that V. cholerae can grab about 150,000 base pairs, which could contain as many as 150 genes, in one stab.

"This finding is very relevant in the context of bacterial evolution," said Blokesch. "It suggests that environmental bacteria might share a common gene pool, which could render their genomes highly flexible and the microbes prone to quick adaption."

Other research studies have examined this question - how much DNA can a bacterium absorb into its genome? This has been done by exposing bacteria in the lab to large amounts of purified DNA. These tests don’t necessarily show what happens in nature, however.

Learn more about the T6SS from the video.

For this work, the scientists took the natural habitat of V. cholerae into account - long bits of DNA aren’t often floating around in nature. DNA that has been freshly released from other microbes can be found, however, and the T6SS can take it up, which sometimes happens on the surface of shells in the ocean and in estuaries, where the microbe often lives.

The researchers examined two strains of V. cholerae that are not related and grew them together on a shell-like or chitinous surface to mimic natural conditions. They found that strains of V. cholerae carrying a functional T6SS system induced by chitin can efficiently transfer DNA in this environment. Large amounts of the genome could be taken up by predatory V. cholerae. The investigators suggested that the evolution of the bacterium is aided significantly by this mechanism.

Sources: AAAS/Eurekalert! via EPFL, eLife

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
AUG 18, 2020
Microbiology
The Science of Pesto
AUG 18, 2020
The Science of Pesto
  The word pesto comes from the Genovese word pestâ (pestare in Italian) which means “to pound” o ...
AUG 14, 2020
Cell & Molecular Biology
A Proposal: COVID-19 is so Deadly Because it Absorbs microRNAs
AUG 14, 2020
A Proposal: COVID-19 is so Deadly Because it Absorbs microRNAs
There are several coronaviruses that we know about, and they cause a wide range of illnesses. Some, like SARS-CoV-2, are ...
SEP 02, 2020
Immunology
Alarmins: The Immune "Gold" in Breast Milk
SEP 02, 2020
Alarmins: The Immune "Gold" in Breast Milk
We know that infants fed with breast milk develop more robust immune systems as a result of factors that support the nat ...
OCT 01, 2020
Microbiology
Investigating the Origins of a Cholera Epidemic
OCT 01, 2020
Investigating the Origins of a Cholera Epidemic
Cholera is an intestinal infection caused by Vibrio cholerae. Cholera has been a scourge throughout human history, and i ...
OCT 06, 2020
Microbiology
Scarlet Fever 'Superclones' Pose Rising Public Health Threat
OCT 06, 2020
Scarlet Fever 'Superclones' Pose Rising Public Health Threat
More than 100 years ago, the world faced waves of scarlet fever epidemics; between around 1820 and 1880 there were sever ...
OCT 11, 2020
Microbiology
Getting Closer to a Vaccine for Flaviviruses
OCT 11, 2020
Getting Closer to a Vaccine for Flaviviruses
Flaviviruses like dengue, West Nile, Zika, Japanese Encephalitis, and yellow fever infect over 400 million people a year ...
Loading Comments...