Soap brand Lifebuoy has launched some truly grimy billboards.

The company's new shopping mall ads are essentially giant Petri dishes in which bacteria swabbed from everyday objects grows before the eyes of passers-by over the course of days.

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The end result is a colorful pattern of living bacterial colonies splayed out around their comparatively small source.

A time-lapse of the bacterial growth Image: the electric factory

The stunt is intended to demonstrate on a super-sized scale the amount of bacteria and fungi that lurk unseen on household items like smartphones, dollar bills and game controllers.

It's unclear, however, whether the company distinguishes between harmful germs and microorganisms that can actually be beneficial to health.

The Unilever-owned brand enlisted a team of microbiologists to build the specially designed enclosures and inoculate them with the samples.

The ads are currently only running in South American shopping malls, and Lifebuoy plans to expand the effort worldwide with a range of new formats starting next year.

Juan Ciapessoni, group chief creative officer at The Electric Factory, the design firm behind the ads, said the campaign is also meant to refute the healthcare advertising trope in which germs are rendered as cartoonish villains.

"Advertising, until now, told you that bacteria are bad and cause disease by showing them as funny and disgusting 3D ‘monsters,’" he said in a statement. "But by making caricatures of the problem, there’s the potential danger that a very real issue could be taken lightly."

The campaign is actually not the first to incorporate living microorganisms into outdoor advertising. An earlier LifeBuoy billboard used samples of ten different germs to spell out the company's name. And marketers for the 2011 movie Contagion used a similar gimmick.

Image: the electric factory