DEC 13, 2015 3:53 PM PST

Better Know a Microbe: Pseudomonas syringae

WRITTEN BY: Kerry Evans
If you’re dreaming of a white Christmas, look no further than Pseudomonas syringae.  This plant pathogen has a very special talent - turning water molecules into rain droplets and ice crystals!

P. syringae is one of 78 species within the genus Pseudomonas and there are a whopping 50 different strains of P. syringae, each one infecting a different plant species.  It was first described way back in 1902 and has become a model organism for plant-pathogen interactions.  It is a Gram-negative, rod-shaped, obligate aerobe with polar flagella - essentially, it looks just like E. coli.  P. syringae loves cool, wet environments within the “phyllosphere” - the above-ground portions of plants - where it colonizes the leaf surfaces of plants like tomatoes, rice, beans, and tobacco.      
 
P. syringae causes disease on plant leaves.

Many strains of P. syringae secrete toxins and enzymes that degrade the plant cell walls.  One toxin, syringomycin, acts like a detergent at high concentrations to dissolve the cell walls.  Syringomycin can also aggregate to form pores in the plant cells, releasing nutrients that are likely utilized by the bacteria.

My favorite thing, without a doubt, about P. syringae is that it nucleates ice crystal and water droplet formation.  These bacteria produce Ina (“ice nucleation active”) proteins that sit on the bacterial cell surface and position water molecules so they can easily form ice crystals at temperatures just below the freezing point.  There are actually so many P. syringae cells on the average leaf that they are largely responsible for damaging frost formation.  While this is bad news for farmers, it’s great news for ski resorts that actually use Ina proteins to make artificial snow!

Last, but not least, I’ll leave you with this Science Friday clip all about ice-nucleating bacteria...
 

Sources: MicrobeWiki, Wikipedia, Science Friday
 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
SEP 11, 2020
Microbiology
Bat Ticks Are Discovered in New Jersey
SEP 11, 2020
Bat Ticks Are Discovered in New Jersey
While only about 25 of 900 species of tick spread disease, ticks are responsible for an estimated 95 percent of vector-b ...
OCT 09, 2020
Microbiology
Two Early Relatives of Rubella Are Discovered
OCT 09, 2020
Two Early Relatives of Rubella Are Discovered
Rubella is a contagious, airborne viral infection that can lead to rash, fever, and sore throat. It's especially dangero ...
OCT 12, 2020
Genetics & Genomics
The Malaria Parasite Can Change Host Cell Genetics
OCT 12, 2020
The Malaria Parasite Can Change Host Cell Genetics
Mosquitoes can transmit the malaria-causing Plasmodium parasite to humans. Malaria was estimated to have caused the deat ...
OCT 18, 2020
Microbiology
Mouth Microbes Play a Role in Oral Cancer Development
OCT 18, 2020
Mouth Microbes Play a Role in Oral Cancer Development
Oral hygiene is not only important for keeping teeth and gums healthy; it can also affect a person's health in general.
NOV 16, 2020
Genetics & Genomics
Hidden Genes in the SARS-CoV-2 Genome
NOV 16, 2020
Hidden Genes in the SARS-CoV-2 Genome
It's essential for organisms to use their genomes to make proteins, and the processes of transcription and translation a ...
NOV 20, 2020
Microbiology
Heavy Metal Exposure Raises Levels of Antibiotic-Resistant Germs in Cows
NOV 20, 2020
Heavy Metal Exposure Raises Levels of Antibiotic-Resistant Germs in Cows
Antibiotic-resistant microbes are considered to be a major public health threat. The overuse of antibiotics is thought t ...
Loading Comments...