Pseudomonas Syringae: Mother Nature’s Cloud Seeding Agents?

Even though the Bergeron-Findeisen theory of rain had been the widely accepted working principle on what causes rainfalls, is there another yet to be discovered mechanism behind precipitation? 

By: Ringo Bones 

Though this microorganism’s role in how rains form has just been discovered relatively recently, it may provide an explanation on why a rainforest or other regions on our planet is an inexplicable magnet for rainfall. Microbiologists and climatologists had just relatively recently found out that the microorganism Pseudomonas syringae that tends to hover above rainforests and other places with dense patches of vegetation has a protein structure that allows water vapor in the atmosphere to freeze just above zero degrees Celsius. The microorganisms themselves act as the nucleating agents that allow rain to form out of atmospheric water vapor that will trigger a rainfall if enough of them coalesce and the Earth’s gravity will do the rest. 

The working principle behind how rains form has been discovered by Swedish meteorologist Tor Bergeron in his white paper published back in 1935 proposing the astonishing theory that most rain begins as snow in the colder parts of the upper atmosphere. This theory was later elaborated by German physicist Walter Findeisen and is now widely accepted as the Bergeron-Findeisen theory of rain which is the working principle behind how rains form and artificial cloud-seeding. Dust blown up into the upper parts of our atmosphere where clouds form, ultrafine dry ice, silver iodide crystals, and even common table salt had been used in artificial cloud seeding with varying degrees of success. Now we can add Pseudomonas syringae to that list. 

Recent studies have shown that Pseudomonas syringae is a more potent nucleating agent for rain formation than dust or ultrafine solid carbon dioxide, silver iodide crystals and table salt. The microorganism has also been employed for awhile now as an ice or snow making bacteria to lower the operating costs of snow machines during the Yuletide season in places that normally don’t get snowfall during that time of the year.

Pseudomonas syringae is a rod-shaped, Gram-negative bacterium with polar flagella. Despite its desirable rainmaking and snowmaking properties Pseudomonas syringae is a potent plant pathogen. As a plant pathogen, it can infect a wide range of species and exists as over 50 pathovars seen as bacterial speck in tomatoes. Ice nucleation induced by Pseudomonas syringae that earned it the nickname the “rainmaking” or “snowmaking” bacteria – depending on the local prevailing atmospheric ambient temperature.