How snow is formed is more interesting than you would possibly think. This basic physical process, one of the common in nature, stays somewhat mysterious despite a long time of scientific scrutiny.
Now recent research from the University of Utah, together with the Max Planck Institute for Polymer Research in Germany and Boise State University in Idaho, is shedding recent light on the role of biological agents produced by fungi — of all things — within the formation of ice.
Contrary to what we're taught in class, water doesn't necessarily freeze at 0 degrees Celsius (32 degrees F) because there may be an energy barrier to the phase transition.
Perfectly pure water won't freeze until it's cooled to -46 degrees Celsius. This is because water molecules need particles on which to form the crystals that result in ice, a process called nucleation. To survive in cold environments, organisms have developed alternative ways to regulate the formation of ice.
So essentially the most efficient ice nucleating particles are biological in origin, produced in bacteria and fungi and even insects, however the molecular basis and exact mechanisms of “biological ice nuclei” will not be well understood.
The ability of fungi to regulate frost
Valeria Molinaro, a theoretical chemist on the University of Utah's College of Science, is on the forefront of unraveling this mystery, which has potential implications for improving our understanding of how life affects precipitation and climate. Is.
In a brand new study, he co-led, a global team of researchers explores the properties and properties of fungal ice nucleators, showing that they're composed of small protein subunits and form ice. They play a job in each promoting and inhibiting growth.
“They are proteins that are released into the atmosphere and these particles are very efficient for ice nucleation,” said Molinero, director of the university's Henry Ehring Center for Theoretical Chemistry. “But how these ice nucleation abilities benefit organisms is not known and is not present in all possible species. We don't know why ice forms or if there is any benefit.”
The multidisciplinary team homed in on a species of fungus and discovered that it produces extremely minute proteins that aggregate into large particles. Their results are published this week, or .
According to co-lead writer Konrad Meister, the mechanism for constructing large aggregates from small constructing blocks is present in organisms apart from fungi.
“Nevertheless, we were surprised by the small size of the fungal protein building blocks compared to their efficiency,” said Meister, a chemistry professor at Boise State. “Other known and similarly efficient ice-making proteins from other organisms are, for example, 25 times larger.”
How organisms evolve in alternative ways to realize the identical result.
Bacteria and fungal proteins can speed up ice formation at temperatures as warm as -10 to -2 degrees. Some bacteria are so effective at promoting snow that they're put to work within the products used to make snow at ski areas.
Molinero is intrigued that so many differing kinds of organisms have developed similar ice-nucleating abilities that he originally titled the paper “”, which implies “many, one,” however the journal insisted that they omit the Latin language.
“If you look at the states that can nucleate ice, there are insects, lichens, bacteria and fungi. They've all evolved independently, very powerful ice nucleators,” he said. “And all ice nucleation in nature that is highly efficient is done by proteins, although the size of individual ice nucleating proteins varies greatly between organisms.”
According to the study, the ecological advantages of ice nucleation and its role in cloud formation and precipitation are still not fully understood, making a critical gap in our understanding of the interaction between climate and life. . The research could lead on to improving the efficiency of freezing food, making ice or cloud seeding.
With the team's discoveries come many questions, nevertheless, about why and the way these proteins assemble.
“The other question is whether they're doing it on purpose or whether it's just a protein they produce for something else, but it has this property,” Molinero said.
Addressing these fundamental questions would require teamwork, bringing together investigators with expertise in various fields of chemistry, biophysics, and biology.
“This is a positive message. Solving the puzzle of the biological control of ice formation forces scientists to collaborate,” Molinero said. “Each of us has a piece of knowledge, but collectively we can do a lot. It's been fun.”
Valeria Molinaro is the Jack and Peg Simons Endowed Professor of Theoretical Chemistry and Director of the Henry Eyring Center on the University of Utah within the Department of Chemistry. Ingrid de Almeida Ribeiro, a postdoctoral researcher within the Molinero lab, is co-first writer of the study.