Researchers have discovered that a bacterium found in kimchi is capable of binding to nanoplastics in the gut and aiding in their removal from the body.
This finding repositions the microbes in fermented foods as potential aids in reducing plastic accumulation in people.
An intestinal test
In a fluid designed to replicate human intestinal conditions, the kimchi microbe was able to hold onto particles that other bacteria tended to release.
At the World Institute of Kimchi, Dr. Se Hee Lee and his team noted that 57% of the particles remained bound.
Meanwhile, a comparison strain saw its binding drop dramatically to just 3% under similar conditions, after initially achieving 85% in standard tests.
This drastic decline for the comparison strain highlighted the kimchi microbe’s significant role in the intestine.
Why plastic sticks to kimchi
The bacterium commonly found in kimchi, Leuconostoc mesenteroides, utilized biosorption—a process where pollutants bind to the surface—to prevent deeper tissue penetration.
Chemical groups on the bacterium’s surface seemed to facilitate the binding process with the plastic, ensuring stable contact.
Before any digestion was simulated, the kimchi bacterium had already attached to 87% of the particles, slightly outperforming the comparison strain’s 85%.
The results across varying temperatures, acidity, and particle loads indicated that the binding effect was robust enough to warrant further animal studies.
Plastic and kimchi in mice
In trials using germ-free mice—those raised without their natural gut microbes—the research team examined the strain devoid of interference.
Mice treated with the kimchi-derived bacterium expelled more than double the amount of nanoplastics in their feces compared to untreated controls.
This increase in waste indicated that a greater quantity of plastic had likely been captured in the intestine before entering the bloodstream. While results in mice don’t confirm safe effects in humans, they suggest a potential mechanism at play.
Why size matters
Nanoplastics—small plastic particles less than approximately 0.00004 inch—can occasionally bypass biological barriers, raising concerns about their persistence in the body.
Studies of human autopsies have revealed increased plastic concentrations in brain samples compared to liver or kidney samples.
However, simply having higher plastic levels in the brain doesn’t directly indicate harm, which brings up questions regarding dosage, timing, and associated risks.
This uncertainty surrounding potential harm underscores the importance of seeking safe methods to prevent particles from entering the body.
How exposure happens
People don’t need to ingest plastics directly; tiny fragments are already present in food, water, and air.
Factors like sunlight, heat, and friction break down larger plastics into smaller particles, making it easier for individuals to consume them over time.
The intestine is particularly crucial because it’s where these particles encounter digestion and bodily tissues.
Using edible microbes in the gut could be an effective strategy for intercepting contaminants right at the entry point.
Why kimchi matters
Kimchi contains lactic acid bacteria, which are essential for fermentation and its characteristic tangy flavor, providing a broad range of food-safe candidates for study.
Unlike many environmental bacteria, kimchi microbes have been consumed safely by people for generations, which enhances their practical application.
The researchers benefited from this long history, allowing them to explore gut strategies without worrying about potential risks from these strains.
This implies that familiar fermented foods could harbor beneficial microbes that serve purposes beyond just flavor and preservation.
Limits of this result
The tests utilized polystyrene as the type of plastic, leaving uncertainties about whether the same strain would bind other common plastics.
Human digestion is also more complex than lab conditions, involving mixed meals and numerous resident microbes.
Long-term studies are necessary to examine real microbial communities and determine whether binding affects absorption or gut health.
Without human trials and rigorous follow-up, the work remains promising yet preliminary regarding plastic exposure.
Plastic pollution and kimchi
This research links plastic pollution to food science and gut biology, highlighting its significance beyond just one fermented dish.
“Plastic pollution is increasingly recognized not only as an environmental issue but also as a public health concern. Our findings suggest that microorganisms derived from traditional fermented foods could represent a new biological approach to address this emerging challenge,” noted Lee.
The findings support this view, as particles were retained in the intestine before entering the body.
What happens next?
It’s essential not to consider a serving of kimchi as a guaranteed remedy for plastic removal because the strain tested was isolated under controlled conditions.
What is administered in controlled doses in a lab does not necessarily reflect what one might consume in a typical meal.
A practical next step would be screening fermented foods for stronger binding strains, followed by careful studies in humans.
Screening these microbes could transform familiar strains into targeted solutions for common contaminants in daily life.
Most existing plastic research has been aimed at pollution once it reaches oceans or other environments, but this study focused on the gut.
By demonstrating that a single food microbe can capture nanoplastics where exposure begins, it offers a tangible, preventative approach.
The study is documented in Bioresource Technology.
