Ultra-resistant bacteria in our microwave ovens

The microbiome is a community of microorganisms, a term generally used to talk about the human microbiome. It is a set of bacteria, fungi or yeasts present in our body. But researchers from the University of Valencia in Spain have observed that the microwave oven also has its own microbiome, despite the extreme conditions in which these bacteria evolve, since the principle of these ovens is that they send electromagnetic waves capable of heating water molecules and therefore food.

Scientists have described the microbiome of 30 ovens used in private kitchens, collective kitchens or laboratories. The first lesson of their analyses is that microwaves kill bacteria that are harmful to humans. That’s the good news. Microwaves actually eliminate dangerous bacteria such as Escherichia Coli, Salmonella or Listeria.

On the other hand, researchers have identified traces of a hundred other bacteria. Some are well known, such as bacillus, micrococcus or staphylococcus. These are bacteria that can be found on the skin and which, in some cases, can be harmful. But there are other, more original ones, called extremophiles. These are organisms that evolve in inhospitable environments, very hot or very cold, very acidic or with high pressures similar to the deep sea. Conditions that would eliminate most bacteria but not these organisms for which these are normal environments.

But don’t worry when you reheat your slice of quiche or your bowl of milk: scientists assure us that, despite the presence of these bacteria, microwaves are not reservoirs of pathogens. This study is here to remind us that these ovens are not virgin places either, contrary to popular belief that microwave cooking kills bacteria and viruses. The researchers remind us that it is necessary to clean them regularly. But for them the interest lies elsewhere: expanding the study of extremophile bacteria because they can lead to biotechnological applications.