Take a deep breath. The air you’re breathing is home to tiny microbes that ride currents like trapeze artists and can swing on transparent air streams for thousands of miles.

That is the subject of an article published July 11 in a special issue of Scientific American on “Wild Ideas in Science” written by two Virginia Tech researchers who are using unmanned systems and mathematical models to study the transport of microbes in the air and water.  The special issue covers what it calls “amazing innovations that just might save the planet and us.”

“Many of the microorganisms we collect in the atmosphere and water are understudied or even new to science. We are only just beginning to appreciate the tremendous biodiversity of microorganisms in our atmosphere, lakes, and oceans,” said David Schmale and Shane Ross.

Schmale is a professor in the School of Plant and Environmental Sciences in the College of Agriculture and Life Sciences. Ross is a professor in the Kevin T. Crofton Department of Aerospace and Ocean Engineering in the College of Engineering. Both Schmale and Ross are affiliated researchers with the Fralin Life Sciences Institute.

The team writes about how they have tracked the acrobatic pathways of microbes through the air and water.

“Microbes in the atmosphere may be pathogens of plants, animals, and people. Some live in the clouds as invisible weather-makers, nucleating rain, hail, and even snow. Others are professional surfers, riding atmospheric waves in search of new homes in new locations,” the team wrote in the article. “Understanding how and when these plant pathogens are transported through the atmosphere to susceptible crops is a prerequisite for managing disease.”

The article is also a window into discoveries using drones to research pathogens.

“New tools and technology enable us to answer important questions about where these microbes are coming from, where they are going, and what they are doing in the atmosphere,” said Schmale.

Schmale and Ross have been tracking different species of fungi in the genus Fusarium in the atmosphere with drones and ground-based sampling devices. One species, Fusarium graminearum, produces spores that may be released from the debris of corn and small grains. When these spores land on wheat and the silks of flowering corn, the fungus takes over the developing kernels. The fungus can produce dangerous toxins that threaten domestic animal health. 

When the team analyzed Fusarium colonies collected in the atmosphere with drones, they found that some of the fungi were airborne for several hours, a sufficient amount of time to be transported in air currents across broad geographic regions.

Dust also makes for handy microbial taxicabs. Some microbes travel across continents on dust particles when they might otherwise be subsumed by ultraviolet light exposure, the team wrote. So popular are the global dust lanes for microbes that an estimated hundreds of millions of tons of African dust land in Florida every year.

The pair also discuss how some microbes can modulate weather. Some strains of the bacterium Pseudomonas syringae produce a protein that may facilitate precipitation through a process known as ice nucleation. This bacterium is part of a commercial product that makes artificial snow.

But Pseudomonas syringae isn’t the only microbial trapeze artist out there. Schmale and his colleagues have collected a wide variety of bacteria and fungi travelling in the air. They also found that the microbes that are associated with precipitation are unique to their geographic locations, which could help with weather prediction or microbial weather modification.

Funding from a number of different programs through the National Science Foundation has supported the researchers' work on the transport of microorganisms in the air and water.

Microorganisms are high fliers not only on land, but also in the sea and other aquatic environments as well. Schmale and Ross discovered that aerosolization of microbes may occur when waves crash, bubbles burst, wind sweeps across still water surfaces, or from impacts from droplets splashing.

Drone tracking dye
Members of the Schmale and Ross Labs are using teams of unmanned aerial systems (UASs), or drones, to study flows in the environment. Here, a harmless fluorescent dye is released into the water. A UAS images the plume to estimate dye concentrations, and water samples are collected around the plume with a 3D-printed device that dips into the water while tethered to the drone. These samples are then returned to land for analysis. Photo credit: Shane Ross.

The team has been collecting microbes using drones and unmanned boats in and over water to better understand the transport and mixing of hazardous agents in the environment. Recent experiments with harmless fluorescent dyes as surrogates have provided new clues to the transport of hazardous agents in the water and air.

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Still breathing?

To paraphrase Morpheus from the "Matrix," “You think that’s air you’re breathing now?” How do you define air? Schmale and Ross say the answer might be more than oxygen — it may be the microbes themselves.

-Written by Amy Loeffler, Kristin Rose, and Kendall Daniels