Mold Cannons: High-Speed Spores on Video

Sept. 22, 2008 — -- Imagine launching an astronaut into space at 5,000 times the speed of sound. That's the acceleration at which some molds discharge microscopic spores into the air, Miami University researchers report in a new study published this month in the online journal PLoS ONE.

But the real news is that the researchers captured the process on video.

"It's absolutely astonishing," said Nicholas Money, one of the botanists who conducted the research. "This is the first time that we're seeing the way these fungi are moving."

And they're moving fast. The spores fly at about 55 mph and can travel a distance of more than eight feet.

In order to capture the microscopic motion of the fungi in a Petri dish, the research team used a high-speed camera that records one million images every four seconds.

The video shows fluid-filled stalks ejecting spores like squirt guns.

"I think it's really wonderful stuff," said Frederick Spiegel, chairman of the department of biological sciences at the University of Arkansas. "It really helps to get actual measurements."

The video allows researchers to more accurately calculate the speed and acceleration of the spores and understand the different ways in which various mold species disperse the reproductive cells.

Previously, botanists were able to see the mold stalks under a microscope, but they couldn't visualize the rapid discharge of the spores.

"It's literally so fast that you sometimes get a hint that there's a flicker of something," said Spiegel, who studies slime molds.

"Everything's over in far less than a blink of an eye," Money added.

The videos show four mold species that typically grow on animal dung and are known to have extremely powerful spore ejection strategies. But the researchers have also recorded yet-to-be-published video of other fungi, including toxic molds that are typically associated with indoor allergies.

"The prevailing view has been that it's airflow within that space that really gets these allergy-causing spores into the air, and therefore into the noses and lungs of inhabitants," Money said.