Researchers find hardy bacteria surviving in microwaves

Bacteria can adapt to a wide range of hostile environments, surviving and even thriving in marine oil spills, ocean-borne plastic trash, industrial brownfields and even the interior of the International Space Station.

Now, researchers have found bacteria that have adapted to arguably one of the most potentially deadly locales imaginable -- microwave ovens.

"Our results reveal that domestic microwaves have a more 'anthropized' microbiome, similar to kitchen surfaces, while laboratory microwaves harbor bacteria that are more resistant to radiation," said researcher Daniel Torrent with Darwin Bioprospecting Excellence SL in Paterna, Spain.

For the study, researchers took microbe samples from 30 microwaves -- 10 in single-household kitchens, 10 in shared spaces like cafeterias and workplaces, and 10 from molecular biology and microbiology labs.

Researchers cultured the strains and performed genetic sequencing on the microbes, detecting 747 different species within 24 bacterial families.

They found that typical microbial communities overlapped between home microwaves and those used to heat food in workplaces. Those bacteria tended to be the same as germs found on typical kitchen surfaces.

"Some species of genera found in domestic microwaves, such as Klebsiella, Enterococcus and Aeromonas, may pose a risk to human health," Torrent said. "However, it is important to note that the microbial population found in microwaves does not present a unique or increased risk compared to other common kitchen surfaces."

Laboratory microwaves tended to contain the highest diversity of microbes, and home microwaves the lowest.

The microbiomes found in microwaves closely resembled the microbes found on solar panels, researchers said.

Researchers speculated that the constant thermal shock and electromagnetic radiation produced by solar panels likely has the same effect on bacteria as microwaves do, killing off all but the most highly resistant microbes.

The new study was published Thursday in the journal Frontiers in Microbiology .

"For both the general public and laboratory personnel, we recommend regularly disinfecting microwaves with a diluted bleach solution or a commercially available disinfectant spray," Torrent said in a journal news release. "In addition, it is important to wipe down the interior surfaces with a damp cloth after each use to remove any residue and to clean up spills immediately to prevent the growth of bacteria."

It's not all bad news, however.

Bacterial strains that can survive microwaves might be useful in industrial processes that require especially hardy microbes, Torrent noted.

More information

Consumer Reports has more on cleaning a microwave .

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