Who says that it is Saint Peter who orders it to rain? A new study has revealed that hidden soil fungi “steal” bacterial DNA to control precipitation.
Tiny organisms not only – bacteria and fungi – have a “superpower” that allows them to reach the atmosphere and pull the rain down.
The conclusion is from a study in March in Science Advances.
To understand how a microbe can control a storm, we first have to look at how clouds turn into rain. High in the atmosphere, water does not always freeze at 0°C. Temperatures are normally much lower at cloud level, but pure water can remain liquid down to a frigid -40°C.
Most rain starts out as ice. In the atmosphere, clouds are full of “superheated” water – liquid that is below the freezing point but has not yet turned to ice because it has nothing to cling to.
For a cloud to turn into rain or snow, it needs a “seed” – a tiny particle that water molecules can cling to to crystallize into ice and then fall from the clouds as rain. Dust, soot and salt – carried into the clouds by the wind – can do this, but they are not very effective. They usually require the temperature to drop significantly before they begin to work. This is where biology comes into play.
Meet the ice producers
For decades, scientists have known about the ice nucleating proteins (INpros) found in certain bacteria such as Pseudomonas syringae.
As bacteria move from plant leaves to clouds to trigger rain. They use special proteins to force water to freeze at temperatures as high as -2°C.
However, recent discovery has revealed a new player in the climate game: fungal INpros.
While bacteria keep their ice-forming proteins “stored” in their “skin”, fungi – mainly Fusarium e Mortierella – release these proteins into the soil around them. Their structure makes these fungal proteins water-soluble and smaller than bacterial ones, and with high ice nucleation activity, which makes them more effective cloud seeds.
Make it rain
This takes us to the cycle of bioprecipitation. Imagine a forest floor covered in these fungi. As the wind blows, its microscopic ice-forming proteins are launched into the clouds. Once there, they act as powerful “seeds”.
Even in relatively warm clouds (above -5°C), these fungal proteins can force water to crystallize into ice. As these ice crystals grow, they become heavy and fall. As they pass through warmer air, they melt and turn into rain.
This creates a cycle:
- fungi grow in the moist soil of a forest
- Fungal proteins are taken to the sky
- rain is triggered by these proteins, watering the forest below
- the growth of more fungi is triggered by rain, starting the cycle again.
Unlike bacteria Pseudomonaswhich use ice to “attack” and damage crops to access their nutrients, these fungi Mortierella They are peaceful partners of plants. They do not seek to destroy. Instead, they release their ice-forming proteins into the surrounding soil, which appears to create a protective shield against harsh conditions and a nutrient-rich environment that helps both the fungus and plant thrive.
The new discovery about fungi is exciting because it shows that Even organisms buried in the ground can influence the atmosphereadding a new dimension to this ancient partnership between life and heaven.
It’s a missing piece in the puzzle of how life and the global climate shape each other. This ability to form ice likely gives fungi a survival advantage. They use ice to pump moisture into their mycelium (a vast underground network of thin fungal filaments), protect themselves from damage from patchy frost, and travel in clouds to reach new locations.
The evolutionary theft
The new research also revealed how fungi in the Mortierellaceae acquired the ability to create ice. When researchers studied the genetic code of fungi, they discovered that they did not develop this trait on their own. Millions of years ago, they “borrowed” the genetic code from bacteria, through a process called horizontal gene transfer.
Think of this as a biological “copy and paste”. While most animals only inherit DNA from their parents, microbes can exchange fragments of genetic code with their neighbors, giving them a instant evolutionary update.
However, these fungi are much more efficient at producing ice than bacteria because the fungus secretes (expels – that is, these proteins exist outside the fungal cell) these proteins, and can coat the environment around it and remain active in the soil even after the fungus is no longer present. These proteins are incredibly resilient. They can be washed into streams, dry and turn into dust, and be carried to the sky by the wind.
Why does this matter?
This discovery could change the way researchers view conservation. If we clear cut a forest – removing all the trees and leaving the land bare, we are not just losing trees. We may be destroy the biological engine that triggers regional precipitation.
As we face a changing climate with more frequent droughts, understanding these fungal INpros may be vital.
One day we will be able to use these natural and biodegradable proteins to “cloud seeding” to create rain.
Many countries (such as the UAE, China and the US) already have cloud seeding programs to protect crops from frost. But this type of cloud seeding – a heavy metal that can persist in the environment.
Fungal proteins offer a natural and biodegradable alternative. They can also protect crops from frost. By forcing the ice to form early and evenly, they release a small amount of heat that acts as a thermal blanket for the plant.
We could use them to make snow on ski slopes with less energy, create better-tasting frozen foods by preventing large ice crystals from damaging food cells, or even develop environmentally friendly cooling systems that don’t rely on harsh chemical refrigerants.
Next time you’re caught in a sudden downpour, take a deep breath. This “smell of rain” could very well be the scent of these little organisms telling the clouds that it’s time to release the water.
