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August 9, 2024
Microwave ovens, a staple in modern kitchens, are not just heating leftovers—they are also home to highly specialized microbial communities, according to a groundbreaking new study. Researchers have discovered that these hardy bacteria, thriving in the extreme conditions of microwave ovens, could have significant implications for both hygiene and potential biotechnological applications.
The study, conducted by a team at Darwin Bioprospecting Excellence SL in Paterna, Spain, explored the microbial ecosystems within 30 microwave ovens. These included devices from single-household kitchens, shared domestic spaces like corporate centers and cafeterias, and laboratories focused on molecular biology and microbiology.
“Our results reveal that domestic microwaves have a more ‘anthropised’ microbiome, similar to kitchen surfaces, while laboratory microwaves harbor bacteria that are more resistant to radiation,” said Daniel Torrent, the lead researcher on the study. This observation highlights how the environment and usage patterns influence the types of bacteria that survive and thrive in these appliances.
Using next-generation sequencing and cultivation techniques, the team identified a total of 747 different bacterial genera across 25 bacterial phyla. The most common phyla found were Firmicutes, Actinobacteria, and Proteobacteria. Interestingly, the diversity of microbial life was lowest in single-household microwaves but highest in laboratory environments, reflecting the different levels of exposure to varied biological materials and conditions.
Among the bacteria found, certain genera were exclusive to specific types of microwaves. For instance, domestic microwaves housed bacteria like Acinetobacter, Bhargavaea, Brevibacterium, and Rhizobium. In contrast, laboratory microwaves were home to more radiation-resistant microbes such as Nonomuraea, Delftia, Micrococcus, and Deinococcus.
The presence of these specialized bacteria, particularly in laboratory settings, points to their ability to withstand the unique challenges posed by the microwave environment, including constant thermal shock, electromagnetic radiation, and desiccation. This adaptation makes them of potential interest for industrial processes where such resilience could be advantageous.
However, the study also raises concerns about hygiene, especially in domestic settings. “Some species of genera found in domestic microwaves, such as Klebsiella, Enterococcus, and Aeromonas, may pose a risk to human health. However, the microbial population in microwaves does not present a unique or increased risk compared to other common kitchen surfaces,” Torrent noted.
To mitigate any potential risks, Torrent advises regular cleaning and disinfection of microwave ovens. He recommends using a diluted bleach solution or a commercially available disinfectant spray to clean the interior surfaces. Additionally, wiping down the interior with a damp cloth after each use and promptly cleaning up spills can help prevent the growth of bacteria.
This study not only highlights the resilience of certain microbes in extreme environments but also underscores the importance of maintaining kitchen hygiene to ensure food safety. The findings may pave the way for further research into the biotechnological applications of these robust bacteria, potentially leading to new innovations in various industries.
