You won't touch it again: scientists have discovered what lurks in kitchen sponges.

Scientists assert that sponges – a kitchen tool that people use daily in their kitchens – are a true paradise for bacteria, as reported by BBC.

The reason is that sponges remain warm, moist, and full of food crumbs, which serve as nourishment for microbes most of the time.

Microbiologist Markus Egert from the Furtwangen University in Germany collected data on the bacterial microbiome of used kitchen sponges. He discovered a staggering 362 species of microbes in these sponges. In some areas, the density of bacteria reached 54 billion individuals per square centimeter.

"This is an incredible number, similar to the count of bacteria found in human stool samples," says Egert.

As is known, sponges are full of pockets and holes, each providing an ideal home for a community of microbes.

Synthetic biologist Linchong Yu from Duke University previously modeled the complex environment of a sponge. He found that holes of varying sizes in the sponge stimulate the greatest growth of microbes.

"They discovered that having different pore sizes in kitchen sponges is indeed important for promoting growth. This makes sense because there are individualist microbes, for example, bacteria that prefer to grow alone. There are also bacteria that thrive in the company of others. Inside the sponge, there are so many different structures or niches that everyone is satisfied," explains Egert.

While sponges are excellent homes for bacteria, they do not necessarily pose a health risk to humans. Bacteria surround us every second; they live on our skin, in the soil, in the air, and so on. Not all of them are harmful; in fact, many perform vital functions. Therefore, the crucial question is whether we should be concerned about the bacteria found in sponges at all?

Egert was able to sequence the DNA of the bacteria most prevalent in kitchen sponges. While it was impossible to identify the exact species of each bacterium, five out of the ten most common species were closely related to bacteria that cause infections in individuals with weakened immune systems.

It is noted that cleaning measures for sponges, such as heating them in the microwave or rinsing them with hot soapy water, have failed to sanitize them. Some bacteria were eliminated, but they were replaced by more resilient strains.

"Our hypothesis is that cleaning measures may lead to a kind of natural selection process, in which a few survivors can grow back to large numbers. If you do this a couple of times, it could result in the selection of bacteria that are better adapted to cleaning," emphasizes the study's author.

Fortunately, none of the bacteria found in the sponges were linked to food poisoning or serious illness. Most bacteria on sponges are not harmful unless pathogens such as salmonella are introduced.

Subsequently, these potentially pathogenic bacteria can transfer from your sponge to plates, utensils, or other surfaces.

Ideally, to avoid danger, scientists recommend changing sponges daily. However, there are also methods that can help extend the lifespan of a sponge.

"There are two simple ways to clean them. You can place them in the dishwasher at the end of the evening or heat them in the microwave for a minute until you see steam coming out. This will kill most pathogens," say the scientists.

Other tips include not storing the sponge in the sink to allow it to dry between uses and thoroughly wringing out moisture and removing food crumbs. However, some may consider using an entirely different tool for dishwashing.

"I wouldn't use kitchen sponges at all. In fact, it doesn't make sense to me to use such an item in the kitchen. A brush is much better because it harbors fewer bacteria and dries faster. It's also easier to clean," summarized Egert.

As a reminder, the microbiologist discussed which public places to avoid during lunch. Although eating in public places has long become a social norm for many of us, microbiology expert Primrose Freestone emphasizes the increased risk of food poisoning in many of these settings.