Combatting Anthrax

A top-down view of the ADVANCED ASTROCULTURE™ plant growth chamber on the ISS, where reddish light illuminates the leafy heads of Arabidopsis plants.

The technology worked so well that the University of Wisconsin collaborators joined forces with KES Science and Technology, Inc., to develop an ethylene scrubber for Earth. The device, called Bio-KES, works wonders in supermarkets where ethylene in the air of produce aisles reduces the shelf life of vegetables. Bio-KES was nominated as Discover Magazine's Product of the Year in 1998, and it's since been shipped across the globe for use by grocers and florists.

Moreover, Bio-KES is the parent of AiroCide TiO2.

"It was a serendipitous discovery," recalls Hayman. Tests showed that Bio-KES not only removed ethylene, but also killed airborne dust mites. Marc Anderson quickly realised why: When ultraviolet (UV) photons strike something coated by TiO2 - like the tubes inside Bio-KES - positive and negative charges appear on its surface. Those charges tear apart nearby water molecules. The OH^- ion, a by-product of the reaction, disrupts organic molecules. It's deadly to dust mites, Anthrax and many other pathogens.

Technicians modified Bio-KES - adding higher-power UV lamps, for example, to give it "an extra kick," says Hayman - and AiroCide TiO2 was born.

In a laboratory at the University of Wisconsin, a plexiglass chamber (left) containing airborne spores covers the entrance to an AiroCide TiO2 unit. Few microbes survive a journey through the machine. The exit port (right) reveals glowing UVC lamps inside.

Dean Tompkins, a colleague of Anderson's at the University of Wisconsin, is in charge of testing AiroCide TiO2. "We don't use real Anthrax," he notes. "That would be too dangerous. Instead, we experiment with one of its non-virulent cousins: Bacillus thurengiensis." During a typical experiment, Tompkins propels a cloud of approximately 1000 spores through the AiroCide chamber. Only 100 or so emerge intact.

Spores that enter AiroCide TiO2 spend at least 5 to 10 seconds in transit through the device. "That's important," adds Hayman, "because pathogens that remain inside longer are more likely to die." To slow the spores, TiO2-coated tubes within the unit are randomly arranged - there's no direct path through the machine. When air moves across the jumbled tubes, the flow becomes turbulent - forcing spores to linger where they can be attacked by OH^- and illuminated by germ-killing ultraviolet light

Such powerful tools against bio-terror indeed seem a far cry from star-trekking greenhouses, but that's how many discoveries are made: You never know what new invention might emerge - like AiroCide TiO2 - or what might be annihilated in the process - like Anthrax!