![\"\"](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/08\/07122046\/SEI_216276500.jpg\")
<\/div>Microwaves heat up food, but don\u2019t necessarily kill bacteria<\/p>\n
Shutterstock\/stockfoto<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
Microwave ovens in homes, offices and laboratories are home to a surprising diversity of bacteria.<\/p>\n
Although microwaves are widely used to heat up food and sterilise samples, the radiation they emit is non-ionising, which means that it doesn\u2019t damage biological molecules. They heat things up by making water molecules vibrate<\/a>, but this only kills bacteria if they reach a high enough temperature.<\/p>\n Nevertheless, repeated bouts of heating and drying mean that microwaves were thought to be a difficult environment for microorganisms to survive in.<\/a><\/p>\n Alba Iglesias<\/a> at the University of Valencia, Spain, and her colleagues took samples from 30 microwave ovens: 10 from single-household, domestic kitchens; 10 from shared kitchens such as corporate centres, scientific institutes and cafeterias; and 10 from molecular biology and microbiology laboratories.<\/p>\n In total, the researchers found 747 different genera of bacteria within 25 bacterial phyla. Diversity was lowest in single-household microwaves, and highest in laboratory appliances.<\/p>\n Many of the bacteria found in shared, domestic microwaves and the single-household microwaves overlapped, and were similar to the bacteria often found on human hands and in other parts of the kitchen. However, those in labs, where food was not cooked, were more distinct and were similar to the microbiome found in other extreme, dry, hot and irradiated environments, such as on solar panels.<\/p>\n <\/p>\n The researchers noted that some bacteria found in domestic microwaves, such as Klebsiella, Enterococcus<\/em> and Aeromonas<\/em>, may pose a risk to human health. However, they say the microbial population found in microwaves does not present a unique or increased risk compared with other common kitchen surfaces. The researchers didn\u2019t respond to an interview request.<\/p>\n