The students in Infectious Disease Pathogenesis Lab will be blogging about the strange and wonderful this semester. This week's guest bloggers are: Marcie Bachler, Alex Brezina, Angela J. Christopher, and Samantha Dirk. Check back next week for a new selection of microbe spotlights.
The Benedict Arnold of Bacteria
Bdellovibrio bacteriovorous is a Gram-negative predator of other Gram-negative bacteria. It invades the other bacteria, its “prey,” by using enzymes to punch a hole to get in. Once this is achieved, the B. bacteriovorous encloses itself into the cell by losing its flagellum and “sealing” the prey cell, also known as the bdelloplast, back together to maintain the contents within it. Inside, the B. bacteriovorous starts to use up the bdelloplast’s nutrients and components to either use it as energy or use it as a building block for what it might need later on. When it’s inside the cell and replicating, it is actually protected from environmental factors trying to disrupt it. Once it is done replicating and has used up all the bdelloplast can offer, it breaks the cell to release its progeny. Then the cycle starts all over.
B. bacteriovorous is not known to be harmful to humans, but it is harmful to human pathogens; therefore, it is being studied for use in biocontrol, water treatment, and
potentially as a living antibiotic.
By Marcie Bachler
Image Source: N. Markelova
Cupriavidus metallidurans is a Gram-negative bacillus that lives mostly in industrial sediments and waste. The bacterium is a mesophile, chemolithroph, and facultative anaerobe. What makes this organism special is its ability to not only resist but also detoxify more than 20 heavy metals in the environment by using several heavy metal export and regulatory proteins encoded on two megaplasmids.
C. metallidurans also has a gold-specific operon that makes it particularly interesting. This bacterium can take aqueous gold (III) tetrachloride and precipitate the liquid into solid gold nuggets. However, this process is quite slow and not very cost effective.
The pathogenicity of C. metallidurans has yet to be determined, but it could play an important role in reducing toxic heavy metals in the future if deemed safe for various uses.
By Alex Brezina
Image Source: Pontificia Universidad Catolicade Chile; Creative Commons Attribution-ShareAlike 2.0 license
The Lancet Liver Fluke
Dicrocoelium dendriticum is a parasitic fluke that lives inside grazing animals like sheep. The adult fluke lives inside the sheep and lays eggs, which are shed with feces. Terrestrial snails become infected when they ingest the eggs. Inside the snail, the parasite undergoes clonal replication and produces hundreds of infective larvae, which are then packaged into slime balls and released. Ants are drawn to the slime balls and eagerly engulf them. The fluke reenters the sheep when they eat the infected ants.
Infection with D. dendriticum in humans is rarely reported in the medical literature. In severe cases, when the parasite is present in large numbers, the following symptoms may occur: cirrhosis of the liver (leading to decreased function), anemia, enlarged liver, digestive disturbance and inflammation of the bile duct. There is treatment for both animals and humans.
By Angela J. Christopher
Image Source: Adam Cuerden
The phylum, Cyanobacteria, contains over 10,000 Gram-negative species. These photosynthetic microbes can live as huge, filamentous colonies or as single cells. Cyanobacteria can survive anywhere, from Antarctica to deserts to the hot springs and acidic bogs of Yellowstone National Park. They’ve also been sent into space (more on that in a bit)!
Cyanobacteria often form special anaerobic cells called heterocysts; here, the bacteria fix atmospheric nitrogen into nitrogen molecules that can be used by plants and fungi for growth. Cyanobacteria were also helpful to us billions of years ago; they can photosynthesize and are thought to have influenced the increase in oxygen in our atmosphere.
When nutrients are abundant, however, Cyanobacteria can grow into a colonial arrangement that spreads over the tops of ponds and lakes. These blooms can sometimes make animals sick and can also cause “swimmer’s itch.”
As space pioneers, Cyanobacteria have been sent to the stars where they lived for 553 days in a near vacuum. They are able to lay dormant for long periods of time thanks to many outer wall protections. They also have an enzymatic switch that allows them to store massive amounts of energy to use minimally in times of need. Researchers think these bacteria could be used to help colonize the moon or Mars. They may have done it once, why can’t they do it again?
By Samantha Dirk
Image Source: Matthew J. Parker