JAN 05, 2016 6:28 PM PST

Better Know a Microbe: Bdellovibrio

WRITTEN BY: Kerry Evans
Bdellovibrio bacteriovorus is definitely the most terrifying bacterial species I’ve written about.  What sets Bdellovibrio apart from other pathogens is that it is quite literally a predator - like, alien hunting Arnold Schwarzenegger in the jungle, predator.
 
Bdellovibrio (right) preys on a larger cell.
Bdellovibrio bacteriovorus is a Gram-negative, motile, “comma-shaped” bacterium that was first described by Stolp and Petzold in 1962.  It is a rather ubiquitous organism, making its home in water, soil, and the mammalian GI tract.

A 2004 Science article breaks down the Bdellovibrio life cycle into eight (frightening) steps:
  1. Not only is Bdellovibrio motile, it is one of the fastest swimmers in the bacterial world, traveling 100 times its cell length every second.  During the initial “attack phase”, Bdellovibrio uses its single flagellum to swim towards its prey (the precise mechanism by which cells locate their prey is not well understood).  
  2. After making contact with its prey cell (other unsuspecting Gram-negative bacteria such as E. coli and Pseudomonas) it becomes permanently attached by the cell pole opposite its flagellum.  This attachment is probably facilitated by interactions between predator and prey lipopolysaccharide molecules and outer membrane proteins.
  3. At this point, things start to get ugly.  Bdellovibrio uses hydrolytic enzymes to make a small hole in the prey cell’s outer membrane and peptidoglycan.  It then uses that hole to gain access to the prey cell’s periplasm (the space between the outer and inner membranes, outside of the cytoplasm).
  4. Next, Bdellovibrio jump starts its DNA replication and cell division machinery so that it can divide.
  5. Now that Bdellovibrio is snugly situated inside its prey’s periplasm, it causes the prey cell to go from rod-shaped to rounded, forming what’s called a “bdelloplast”.  
  6. By this time, Bdellovibrio has worked up an appetite, so the predator cell siphons nutrients and ATP out of the prey’s cytoplasm.  The predator cell then grows into a long filament and eventually divides into daughter cells
  7. After division, the daughter cells develop flagella and use hydrolytic enzymes to degrade the prey cell’s outer membrane.
  8. Last, but not least, the new predator progeny cells are released from the prey cell to wreak further havoc (yikes).
Bdellovibrio life cycle

There is a lighter side to Bdellovibrio.  Some researchers think these cells can be used as “living antibiotics” to seek out and destroy infecting pathogens.  There has even been a trial to use Bdellovibrio to eradicate Salmonella enteridis from chicks.  The “treatment” reduced the number of Salmonella cells and caused no significant side effects in the birds when compared to a non-predatory mutant.  This is good news for the poultry industry, since it could cut down on the use of antibiotics and possibly curb the spread of antibiotic resistance.

Sources: Science, MicrobeWiki, Wikipedia, Applied and Environmental Microbiology
 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
NOV 13, 2019
Microbiology
NOV 13, 2019
As Arctic Sea Ice Declines, a Deadly Virus Spreads Among Marine Mammals
Sea ice in the Arctic melts every summer and refreezes in the winter, but the melting has been outpacing the refreezing for many years....
NOV 15, 2019
Microbiology
NOV 15, 2019
Probiotics Linked to Bloodstream Infections in ICU Patients
Probiotics, which are live microbes, are intended to improve human health, and they are sometimes given to intensive care unit patients of all ages....
NOV 25, 2019
Drug Discovery & Development
NOV 25, 2019
Darobactin: Promising New Drug to Combat Antibiotic Resistance
Every year, around 700,000 people are estimated to die from drug-resistant infections thanks to our overuse of antibiotics both in agriculture and medicine...
NOV 28, 2019
Microbiology
NOV 28, 2019
Measles Outbreaks Strike Samoa, DRC
The largest measles outbreak in the world is now occurring in the Democratic Republic of Congo. Over 5,000 people have died from the illness....
DEC 09, 2019
Microbiology
DEC 09, 2019
A Single-Celled Organism That Seems to Make Choices
A protist has been captured on video 'changing its mind.'...
JAN 14, 2020
Microbiology
JAN 14, 2020
Bacterial Growth That is Truly Cultured
Scientists have learned that when certain bacteria are paired together, they create patterns that look like flowers....
Loading Comments...