An international group of researchers has discovered fungal proteins that can catalyze ice formation at high subzero temperatures. One potential application of this discovery could be to engineer weather.
In a process called cloud seeding, particles that can trigger the water in the clouds to turn into ice crystals, called ice nucleators, are released into clouds. The ice crystals then grow as more and more water molecules stick to them. In a kind of snowball effect, the ice crystals grow and become heavier, fall toward the ground, melt as they pass through the atmosphere and become rain. The traditional particle used for ice nucleating is silver iodide, which is highly toxic. The researchers believe this fungal protein molecule could provide a better, safer alternative.
The group also found evidence that the fungal gene encoding the ice nucleation protein was likely acquired by a fungal ancestor from a bacterial species horizontal gene transfer, at least hundreds of thousands, if not millions, of years ago.
“It is known that fungi can acquire genes from bacteria, but it’s not something that is common,” said study author Boris Vinatzer Vinatzer, an affiliate with the Translational Plant Sciences Center at Virginia Tech. “I never expected that this fungal gene had a bacterial origin.”
Researchers have known that fungi are capable of ice nucleation since the early 1990s. Only recently, however, have advances in DNA sequencing and computer science allowed them to sequence the genomes of the specific class of fungi—the Mortierellacae family—and discover the gene that encodes the ice nucleation protein.
While researchers still don’t know how fungi benefit from the acquired gene, they do know that the fungi have made modifications over the years to make it even better—and that translates into human benefit, as well.
For example, in the preparation of frozen foods, the fungal molecule would be safer than the bacterial one because the fungus just secretes the ice nucleation molecule, but the whole bacterial cell would be needed in the bacterial ice nucleation. More potential uses for fungal ice nucleation include climate modeling and cryopreservation of cells.
“Adding a fungal ice nucleator, which is a relatively small molecule, makes the water around the cell freeze much earlier before it gets very cold, to protect the delicate cell inside,” Vinatzer said. “You couldn’t do that with the bacteria because you would have to add entire bacterial cells.”
Data from Virginia Tech