Key Points:
- Extremophiles, resilient microbes, were found thriving in microwave ovens.
- The study challenges the belief that microwave radiation kills all bacteria. It identified 101 bacterial strains, including some linked to food-borne illnesses.
- Laboratory microwaves showed the highest bacterial diversity, including extremophiles.
- Regular cleaning of microwaves is recommended to reduce bacteria.
Extremophiles, organisms that survive and even thrive in the most extreme environments, have now been found in a surprising new location: microwave ovens. This discovery, published in Frontiers in Microbiology, reveals that these resilient microbes can endure the harsh conditions inside microwaves, challenging the widespread belief that microwave radiation kills all bacteria.
While previous studies have identified microbial communities in kitchen appliances like dishwashers and coffee machines, this is the first time the microwave oven has been examined for its microbiome. The study raises awareness that microwaves may not eliminate bacteria that cause food-borne illnesses, such as Escherichia coli and Salmonella.
Jason Tetro, a microbiologist known as “The Germ Guy,” highlights the importance of this study in revealing potential pathogens in microwave ovens, especially in shared settings. The research team, led by Alba Iglesias from the University of Valencia in Spain, swabbed 30 microwave ovens from various environments, including households, offices, and laboratories. The samples were cultured, and the bacterial genera were identified through DNA sequencing.
The results showed that 101 bacterial strains were present, with the dominant ones belonging to the Bacillus, Micrococcus, and Staphylococcus genera. These bacteria are commonly found on human skin and frequently touched surfaces. These bacteria were especially prevalent in household and shared-use microwaves. Some bacteria associated with food-borne illnesses, like Klebsiella and Brevundimonas, were found in household microwaves.
Interestingly, laboratory microwaves exhibited the greatest genetic diversity of bacteria, including extremophiles capable of surviving the radiation, high temperatures, and extreme dryness within these appliances. Manuel Porcar, a co-author of the study, noted that extremophiles might have been evolutionarily “selected” by surviving repeated exposure to microwave radiation. These resilient strains could have potential biotechnological applications, such as bioremediation of toxic waste.
For the general public, the study emphasizes that while microwaves are not “pure, pristine places,” they are not necessarily breeding grounds for dangerous pathogens either. However, Porcar recommends regularly cleaning your microwave, just as you would any other kitchen surface, to reduce the presence of potential bacteria.
