Hello everyone and welcome back! In the US there have been waves of cold weather, creating snow storms, at some locations, in the process. Well, though some like it cold, this Caribbean girl would prefer some warmer weather soon haha! So, as much as it’s fun looking at snow on a macro scale…what if I told you that there are microbes that may help create it? This week, I will therefore speak a little about Pseudomonas syringae.
The gram-negative bacterium Pseudomonas syringae is rod-shaped, can move, and infects plants. There are several strains/types of this microbe (around 50 in fact…with each strain affecting each plant species differently), and gets its name from the tree species from which it was first found (Syringa vulgaris…a.k.a. the lilac tree). If you are a student, can you quickly research who isolated P. syringae back in 1902?
Since some strains are plant pathogens (causing disease in plants), these can secrete a toxin called syringomycin, that affect plant cell membranes. P. syringae can be found colonizing the surface of leaves (known as the phyllosphere), but if pathogenic, they end up destroying their ‘homes’, by forming lesions, for example.
But here’s where it gets very interesting…this microbe is able to create its own ice! Yes, you read that correctly haha. They are living ice makers. They have surface proteins that imitate ice crystal structure, encouraging attachment of more water molecules to them. When this happens, frost damage is possible on plant tissue when temperatures are a little below freezing. There is a quite amazing video that shows water freezing almost instantly when these microbes are added it!
What’s more interesting, is that P. syringae seems to have a greater influence on snow formation, and other forms of precipitation, than previously thought. Additionally, this microbe is used to even create artificial snow at some snow resorts! Pretty cool, don’t you think? (no pun intended 😉)
Take care until next time! 😊
For more information on P. syringae, see link 1, link 2 and link 3. Also see the following link for more on syringomycin. Credit is given for use of images of icy plant leaves, ski location and P. syringae.
jtbtrinbagomicrobiologist 
