Ant armor may provide insight into mineral formation

By Meghan Chua


A possible clue to how one common but hard-to-synthesize mineral forms has shown up in an unlikely place, thanks to collaboration between bacteriology and geoscience labs at UW–Madison.

Geoscience graduate student Yihang Fang studies how the mineral dolomite forms. Dolomite, which contains carbon and magnesium, is useful for water and oil storage and may help lock excess carbon out of the atmosphere, yet is rarely found in modern geological sources.

Yihang Fang
PhD student Yihang Fang, pictured at the Eden Quarry in central Wisconsin, studies how the mineral dolomite forms. Fang has received a Smithsonian Fellowship for his work.

Researchers like Fang try and synthesize it in the lab to better understand the conditions under which it forms, such as high-temperature, high-pressure environments. Previous work from his research group has found that some microbial organisms can also catalyze dolomite precipitation from mineral-rich water that leaves behind a high-magnesium crystal after evaporating.

The newest method that Fang will explore was inspired by a collaboration between professor Cameron Currie’s bacteriology lab at UW–Madison and professor Huifang Xu’s geoscience research group. When researchers in the Currie lab noticed crystals growing on the leaf-cutter ants they study, they sent samples to Xu’s research group to identify the mineral. It turned out to be high-magnesium calcite that could also provide insights on dolomite formation.

Their analysis suggests that a protein layer on the leaf-cutter ants could be the catalyst that allows the magnesium-rich calcite layer to grow. This mineral layer likely serves as armor for the ants, providing defense from other attacking ants or parasites.

Fang will test whether protein control is the mechanism helping the ants form their armor, and how that same method could be used to synthesize dolomite, as a fellow at the Smithsonian Institute National Museum of Natural History. As a fellow, he will have access to the Smithsonian’s vast collection of minerals to use for experiments.

“Through that, we can prove whether this mechanism is actually working or [if there is] some other mechanism that is helping the leaf-cutter ants to get this dolomite armor,” Fang said. He is one of six graduate students in the Big Ten Academic Alliance awarded the fellowship this year.

Pinning down the mechanisms that help dolomite form can aid geoscientists in learning more about the formation of Earth itself. For instance, areas with lots of dolomite formations could show where large amounts of surface water existed following an ice age if that dolomite formed through precipitation.

Fang has held a love for geoscience since he was young. A book he read as a child inspired his curiosity in learning how the earth formed and how minerals played a role. He came to UW–Madison as an undergraduate in 2010 and declared a geoscience major in his freshman year. After earning a bachelor’s degree in geoscience, mathematics, and physics, Fang completed a master’s degree at UW with his undergraduate research advisor, working on mineral precipitation.

For the first year of his PhD, Fang studied at the University of Hawaii, working on high-pressure, high-temperature synthesis experiments aimed at understanding the properties of the Earth’s core. After that year, he returned to UW–Madison to continue the work on carbonate precipitation from his master’s degree.

“The more you study, this stuff just gets more interesting – and there are more questions,” Fang said.

Fang said that there are so many opportunities for collaboration as a graduate student at UW–Madison. If he has a question outside his area of expertise, for instance, there are multiple people in other departments that he can ask about it.

“What I love about Madison, besides the beautiful city and all the fun things that are going on around us, is it’s like a wonderland but for grad students,” Fang said. “You can get all the stuff you want all in one place. There are just so many resources you can use.”

After he graduates, Fang hopes to find a job in academia to continue his geoscience research.