MAR 23, 2016 11:02 AM PDT

Better Know a Microbe: Haloquadratum

WRITTEN BY: Kerry Evans
Haloquadratum” literally means “salt square”.

These salt-loving, square-shaped microbes are some of the most unique archaebacteria out there. Haloquadratum walsbyi was first discovered by A.E. Walsby in 1980 in the Gavish Sabkha, a hypersaline pool in Sinai used by Bedouins to collect salt. Thus, these guys are also known as “Walsby’s square archaeon”.
 
Four Haloquadratum cells line up to form a sheet.

H. walsbyi is highly abundant in salty waters worldwide, but very difficult to culture in the lab. They are likely the most halophilic organisms yet discovered, since they can grow in medium containing 2 M MgCl and 3.3 M NaCl (that’s about 10 times saltier than seawater!).

Their cells are typically 0.1 micron thick and 1.5 microns square. They form fragile, two-dimensional sheets made up of 10 cells, on average. The periphery of each cell is lined with gas vesicles that probably help H. walsbyi move through the environment.
 
Gas vesicles (GV) line the cell periphery.

So, why is it so strange for these cells to be square? In most bacteria, the cytoplasm is usually hypertonic, meaning that osmotic pressure causes cells to swell. Since H. walsbyi lives in hypersaline waters, its interior may actually by hypotonic, making the cells flat. This doesn’t really explain why the cells are square, however. Although, a related species, H. japonica, is triangular, and a specific glycoprotein helps regulate its shape. The same may be true for our square friends.
 
H. japonica are triangle-shaped.

So, they’re square and they like saltwater. Who cares? Planetary scientists do! Jupiter’s moons Europa and Ganymede are both salty, so it’s possible that halophilic organisms like Haloquadratum could be making a home there.

Sources: MicrobeWiki, Skeptic Wonder, Wikipedia
 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
SEP 15, 2020
Microbiology
If They Must, Methane-Eating Microbes Will Consume Ammonia
SEP 15, 2020
If They Must, Methane-Eating Microbes Will Consume Ammonia
There are many different kinds of microbes, and some can use unusual substances to survive. Methanotrophs, for example, ...
SEP 23, 2020
Microbiology
Poxvirus Made Harmless After Removing One Gene
SEP 23, 2020
Poxvirus Made Harmless After Removing One Gene
Poxviruses are deadly viruses that are known to infect both animals and humans. Cowpox and monkeypox are both known to s ...
SEP 30, 2020
Microbiology
Bringing Attention to a Neglected Disease
SEP 30, 2020
Bringing Attention to a Neglected Disease
Schistosomiasis doesn't get much research attention, but it affects around 240 million people around the world, killing ...
OCT 05, 2020
Microbiology
Deadly Microbe Linked to Childhood Brain Disorder
OCT 05, 2020
Deadly Microbe Linked to Childhood Brain Disorder
Pediatric hydrocephalus - excessive fluid on the brain of a child - has been connected to a bacterial pathogen.
NOV 06, 2020
Microbiology
Daily Aspirin Users Less Likely to Die From COVID-19
NOV 06, 2020
Daily Aspirin Users Less Likely to Die From COVID-19
Recent work has backed up research from earlier this year that suggested that aspirin might help prevent the worst cases ...
NOV 09, 2020
Microbiology
Fighting COVID-19 with Help From Llamas
NOV 09, 2020
Fighting COVID-19 with Help From Llamas
Camelids, which include llamas, alpacas and camels have immune systems that generate two kinds of antibodies when confro ...
Loading Comments...