Novel probiotics adsorbing and excreting microplastics in vivo show potential gut health benefits

Microplastics contamination in food and water poses significant health risks. While microbes that form biofilm show potential for removing microplastics from the environment, no methods currently exist to eliminate these non-degradable particles from the human body.

In this study, we propose using probiotics to adsorb and remove ingested microplastics within the gut. We conducted a comprehensive evaluation of 784 bacterial strains to assess their ability to adsorb 0.1 μm polystyrene particles using a high-throughput screening method. 87 strains showed >60% adsorption ratio using FITC-labeled particles in 96-well plates, measured by fluorescence decrease after incubation.

Among the tested strains, Lacticaseibacillus paracasei DT66 and Lactiplantibacillus plantarum DT88 exhibited optimal adsorption in vitro and were effective across various microplastic types. In an animal model, mice treated with these probiotics demonstrated a 34% increase in polystyrene excretion rates and a 67% reduction in residual polystyrene particles within the intestine. Additionally, administration of L. plantarum DT88 mitigated polystyrene-induced intestinal inflammation.

Introduction

Plastics are everywhere. Approximately 80% of manufactured plastics are improperly processed, resulting in plastic pollution in the natural environment.¹Geyer R, Jambeck JR, Law KL (2017) Production, use, and fate of all plastics ever made. Science Advances. Open → Under physical, chemical, and biological pressures, plastics disintegrate into particles less than 5 mm — known as microplastics (MP) — that have dispersed into soil, water, atmosphere, and even living creatures.²Osman AI et al. (2023) Microplastic sources, formation, toxicity and remediation: a review. Environ Chem Lett. Open →

Microplastic contamination has been found in daily food and drinking water. It is reported that up to 5 grams of microplastics could be consumed per person per week — roughly the weight of a credit card.³Senathirajah K et al. (2021) Estimation of the mass of microplastics ingested. J Hazard Mater 404:124004. Open → The ingested particles can translocate across the gastrointestinal mucosa and deposit in biological fluids and organs.^4,5Powell JJ et al. (2010) Origin and fate of dietary nanoparticles in the GI tract; Sun J & Wang X (2023) Microplastics: a new environmental pollutant. Given their inert chemical properties, microplastics cannot be metabolized or degraded inside the human body.

A recent landmark study showed that people who had microplastics lodged in their carotid artery were 4.53× more likely to experience heart attack over a 34-month follow-up.⁶Marfella R et al. (2024) Microplastics and nanoplastics in atheromas and cardiovascular events. NEJM 390(10):900–910. Open →

Probiotics have demonstrated the ability to protect against health damage caused by toxic materials such as heavy metals and plasticizers, by either binding to or degrading these toxins.^7–12Multiple studies (2013–2022) on probiotic binding of heavy metals, plasticizers, and microplastics in seawater. See references 7–12. Despite beneficial effects in countering MP-induced damage, few approaches have been reported for removing ingested microplastics from the human body. This study set out to explore that possibility.

Screening 784 strains for microplastic adsorption

784 probiotic strains isolated from fermented foods were screened using a high-throughput fluorescence assay. Bacteria were incubated with FITC-labeled polystyrene particles in 96-well plates; those that adsorbed and precipitated the particles produced a measurable drop in supernatant fluorescence.

87 strains showed an adsorption ratio greater than 60%, with the highest reaching 80.5%. Three strains were selected for deeper analysis:

• L. plantarum DT88 — 79.8% adsorption ratio (top performer)
• L. paracasei DT66 — 71.4% adsorption ratio
• L. plantarum DT22 — 6.2% adsorption ratio (low-adsorbing control)

To confirm that this binding works across real-world plastic types (not just polystyrene), the researchers used scanning electron microscopy (SEM) to visualize bacteria-plastic aggregates with five different plastics:

The SEM images are striking: DT66 and DT88 bacteria completely coat the plastic particle surfaces, forming dense aggregates. The low-adsorbing control (DT22) shows only scattered bacteria. This binding is not specific to polystyrene — it works across polypropylene (food containers), polyethylene (bags, films), polycarbonate (bottles), and PET (water bottles). These five plastic types account for the vast majority of microplastic contamination found in food and drinking water.

Probiotics accelerate microplastic excretion

With binding confirmed in vitro, the next question was whether these probiotics could actually help remove microplastics from a living gut. Mice were given probiotics daily for seven days, then fed fluorescent polystyrene particles. After 20 minutes, their intestines were imaged.

The researchers also explored whether the probiotics' production of short-chain fatty acids (SCFAs) might contribute by speeding up gut motility. Butyric acid levels did increase in probiotic-treated mice, suggesting gut motility may play a secondary role alongside the primary adsorption mechanism.

Probiotics reduce microplastic retention

Faster transit is useful, but the critical question is whether probiotics reduce the amount of plastic that accumulates in intestinal tissue over time. In a longer-duration experiment, mice received both probiotics (morning) and polystyrene particles (afternoon) for seven consecutive days, then fasted for 16 hours before tissue analysis.

The results were dramatic. In the ileum:

• PS-only mice: ~1,900 mg/kg of residual polystyrene
• DT66-treated: ~700 mg/kg (62% reduction, p<0.001)
• DT88-treated: ~630 mg/kg (67% reduction, p<0.001)

Similar reductions were observed in the cecum. The low-adsorbing control strain (DT22) had no significant effect. DT22 is a probiotic — it survives acid and bile — but it does not bind plastic. This rules out the possibility that generic probiotic effects (like microbiome modulation) are responsible for the observed MP reduction. The benefit comes specifically from the adsorption capacity.

Probiotics ameliorate MP-induced inflammation

Beyond removing plastic, the probiotics also addressed the damage that microplastics cause. Polystyrene exposure triggered measurable intestinal inflammation in the mice — decreased anti-inflammatory IL-10 and elevated pro-inflammatory cytokines (IL-6, TNF-α, IL-1β).

L. plantarum DT88 showed the strongest anti-inflammatory effect:

• IL-10 (anti-inflammatory): PS exposure decreased it; DT88 fully restored it to baseline levels (p<0.0001)
• TNF-α: PS increased it to ~5,500 pg/g; DT88 significantly reduced it (p<0.0001)
• IL-6: PS increased it to ~850 pg/g; DT88 reduced it to ~500 pg/g
• IL-1β: PS increased it; DT88 reduced it (p<0.01)

Discussion

This is the first study to demonstrate a probiotic-based strategy for removing microplastics from the gastrointestinal tract of a living organism. The mechanism appears to be primarily physical — the bacteria bind to microplastic particles via hydrophobic surface interactions, forming larger aggregates that are then excreted through normal gut transit. The binding is likely mediated by hydrophobic cell-surface proteins and exopolysaccharides common to Lactobacillus strains.

A key strength of this study is the use of DT22 as a negative control — a probiotic strain with low adsorption capacity. This controls for the general benefits of probiotic supplementation (microbiome modulation, immune support) and isolates the specific contribution of microplastic adsorption.

The breadth of plastic types that DT66 and DT88 can bind is noteworthy. The SEM images show adhesion to PS, PP, PE, PC, and PET — the five most common plastics found in food and water contamination. This suggests the binding mechanism is general-purpose, not specific to one polymer chemistry.

Limitations and future directions: This study was conducted in mice, and the dosing regimen (1×10⁹ CFU/day) would need to be validated in human trials. The typical probiotic supplement contains 10⁹–10¹⁰ CFU per dose, so the doses used are within the range of commercially available products. The study examined polystyrene particles of defined sizes; real-world microplastic exposure involves a heterogeneous mix of particle sizes, shapes, and polymer types. Long-term safety data and optimal dosing remain to be established.

This article is an enhanced web presentation of the original open-access paper published in Frontiers in Microbiology under the Creative Commons Attribution License (CC BY 4.0). All text, data, and figures are from the original publication by Teng, Zhang & Rao (2025). Presented by DetoxBio for educational purposes.