Your Microwave Could Be a Haven for Surprisingly Resilient Bacteria

If you haven’t sanitized your microwave in a while, you may want to get on that. A new study has revealed that these kitchen appliances can harbor some of the most resilient microbes yet discovered.

The researchers examined 30 microwaves and found that nearly 750 different species of bacteria call these appliances home, including some that you wouldn’t want in your food or on your fingers.

“Some species of genera found in domestic microwaves, such as Klebsiella, Enterococcus and Aeromonas, may pose a risk to human health,” said Daniel Torrent, a researcher at Darwin Bioprospecting Excellence SL, who worked on the study. “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.”

Klebsiella, for instance, is a bacteria normally found in human feces that the Centers for Disease Control and Prevention says can cause pneumonia and blood infections in humans, adding that it’s “becoming increasingly resistant to antibiotics.” Enterococcus and Aeromonas are just as concerning.

It might seem counterintuitive that anything can survive a microwave oven, which heats up food by blasting it with radiation. Microwaves are a form of non-ionizing radiation, meaning they lack the energy to alter cells and atoms, and the levels found in your kitchen microwave are not believed to be dangerous to humans. While putting your food in a microwave for an appropriate period of time does kill microbes, according to the FDA, that’s due to the heat that’s generated, not the radiation itself.

Not all microwaves host the same types of microbiomes. Rather, they take on some of the microscopic characteristics of the surrounding area. The study found that microwaves in shared spaces or single-home kitchens had bacteria that was different and less diverse than microwaves located in laboratories.

“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 Torrent.

Though lab microwaves have different microbiomes from their domestic counterparts, they were similar to those on solar panels. The researchers theorized that the conditions in both environments, such as the presence of electromagnetic radiation and constant changes in heat, mean only the hardiest species of bacteria can survive.

If this is all turning you off from nuking that frozen chicken pot pie for dinner, fret not. Torrent recommended giving your personal kitchen bacteria farm a regular cleaning with diluted bleach or disinfectant spray, and to clean up any messes quickly to prevent bacterial growth.