Research shows that some bacteria from pig farms can work as probiotics, but safety varies dramatically by strain. A 2026 study of eight bacterial strains found that two showed excellent probiotic qualities with no dangerous genes, while one strain carried antibiotic-resistance genes it could transfer to other bacteria. According to Gram Research analysis, this highlights why whole-genome safety testing is essential before using any probiotic supplement.
Scientists tested eight types of bacteria from pig farms to see if they could work as probiotics—supplements that help your gut health. They found that some bacteria were great at surviving stomach acid and sticking to your intestines, which are important probiotic traits. However, the researchers discovered a major safety problem: some bacteria carried genes that make them resistant to antibiotics, and they could even pass this resistance to other bacteria. According to Gram Research analysis, while two of the bacteria strains showed real promise as safe probiotics, one strain posed significant risks that need careful monitoring before it could be used in supplements.
Key Statistics
A 2026 research article analyzing eight lactic acid bacteria strains from pig farms found that Pediococcus pentosaceus R124 achieved 54.11% adhesion to intestinal epithelial cells, a key marker of probiotic effectiveness.
In the same 2026 study of eight bacterial strains, Lactiplantibacillus plantarum Z108 demonstrated 24.18% survival at pH 2.0, showing exceptional acid resistance comparable to leading commercial probiotics.
A 2026 analysis of eight pig farm-derived bacterial strains revealed that Enterococcus faecium F130 carried thirteen antibiotic-resistance genes, eight of which were located on transferable plasmids capable of spreading resistance to other bacteria.
Research on eight lactic acid bacteria strains published in 2026 demonstrated that two strains (P. pentosaceus R124 and L. plantarum Z108) showed antibiotic resistance without carrying acquired resistance genes, suggesting intrinsic rather than dangerous acquired mechanisms.
The Quick Take
- What they studied: Can bacteria from pig farms work as probiotics, and are they safe enough to use in supplements or food?
- Who participated: Eight different strains of lactic acid bacteria (the good bacteria used in yogurt and fermented foods) isolated from fecal samples at large pig farms
- Key finding: Two bacterial strains showed excellent probiotic qualities and no dangerous genes, but one strain carried antibiotic-resistance genes that it could spread to other bacteria—a serious safety concern
- What it means for you: Not all probiotics are created equal. Before buying a probiotic supplement, you should know whether it’s been tested for antibiotic-resistance genes, especially if it comes from animal sources. This research suggests manufacturers need stricter safety testing.
The Research Details
Researchers collected bacteria samples from pig farm waste and grew eight different strains in the laboratory. They then ran multiple tests to see how well these bacteria could survive in conditions similar to your stomach and intestines. They tested how well the bacteria could stick to intestinal cells, survive stomach acid, and tolerate bile (a digestive fluid). They also checked if the bacteria were harmful by looking for hemolysis, which is when bacteria destroy red blood cells.
The most important part of the study involved DNA sequencing—reading the complete genetic code of each bacterial strain. This allowed scientists to search for specific genes that make bacteria resistant to antibiotics and genes that could make them harmful to humans. They also performed a special test called filter-mating to see if antibiotic-resistance genes could jump from one bacterial strain to another.
This approach is important because it combines two types of testing: functional tests (does it work as a probiotic?) and genetic safety tests (could it harm you?). Many probiotic products are only tested for whether they work, not whether they carry hidden genetic dangers. This study shows why both types of testing matter.
The study is well-designed because it uses whole-genome sequencing, which is the gold standard for identifying genetic risks. The researchers tested for both antibiotic resistance and virulence factors (genes that cause disease). However, the study only tested eight strains, which is a relatively small number. The results are published in PeerJ, a peer-reviewed scientific journal, which means other experts reviewed the work before publication.
What the Results Show
Two bacterial strains stood out as promising probiotics. Pediococcus pentosaceus R124 was excellent at sticking to intestinal cells (54.11% adhesion rate) and had strong coaggregation ability, meaning it could clump together with other beneficial bacteria. Lactiplantibacillus plantarum Z108 was a champion at surviving stomach acid, with 24.18% of the bacteria surviving at pH 2.0 (extremely acidic conditions). Enterococcus faecium F130 showed the best tolerance to bile salts, which is important for surviving in the small intestine.
However, the safety findings were concerning. All eight strains showed antibiotic resistance when tested in the lab, but the genetic analysis revealed very different stories. The two promising strains (R124 and Z108) had no acquired antibiotic-resistance genes in their DNA, suggesting their resistance came from natural, built-in mechanisms rather than dangerous genes they picked up. This is much safer than acquired resistance.
The third strain, E. faecium F130, was a different story entirely. It carried four virulence factor genes (genes that could cause disease) and thirteen antibiotic-resistance genes. Even more worrying, eight of these resistance genes were located on plasmids—small circles of DNA that can easily transfer between bacteria. In fact, the researchers proved that this strain could pass its antibiotic-resistance plasmid to other bacteria through a process called horizontal gene transfer.
All eight strains showed a non-hemolytic phenotype, meaning they didn’t destroy red blood cells, which is a good safety sign. The study also revealed that antibiotic resistance patterns varied significantly between strains, suggesting that not all bacteria with the same name behave the same way. This highlights the importance of testing individual strains rather than assuming all members of a species are identical.
This research aligns with growing concerns in the scientific community about antibiotic resistance in probiotics. Previous studies have shown that some probiotic products contain bacteria with resistance genes, but this study is notable for demonstrating actual horizontal gene transfer—proof that resistance can spread. The finding that some bacteria have intrinsic (natural) resistance without acquired genes is consistent with what scientists know about how bacteria naturally survive harsh conditions.
The study only tested eight bacterial strains, so the results may not apply to all probiotics from pig farms. The research was conducted in laboratory conditions (in vitro), which don’t perfectly mimic what happens in a real human digestive system. The study didn’t test whether the bacteria would actually transfer resistance genes in a living animal or human body. Additionally, the sample size of bacteria tested is small, so these findings should be confirmed with larger studies before making broad recommendations about probiotic safety.
The Bottom Line
If you’re considering a probiotic supplement, especially one derived from animal sources, look for products that have undergone whole-genome sequencing safety testing. Strains like P. pentosaceus R124 and L. plantarum Z108 appear to be safer choices based on this research. Avoid probiotics containing E. faecium strains unless the manufacturer can prove the specific strain has been tested for antibiotic-resistance genes and virulence factors. Confidence level: Moderate—this is one study with a small sample size, but the findings are scientifically sound.
Anyone considering probiotic supplements should care about this research, particularly people with weakened immune systems, those taking antibiotics, or anyone concerned about antibiotic resistance. Healthcare providers and probiotic manufacturers should use these findings to improve safety testing standards. People who don’t take probiotics don’t need to change their behavior based on this study alone.
If you start taking a safe probiotic, you might notice digestive improvements within 2-4 weeks, though some people see benefits sooner. However, the main benefit of this research isn’t about how quickly probiotics work—it’s about ensuring the ones you take won’t contribute to antibiotic resistance, which is a long-term public health concern.
Frequently Asked Questions
Are probiotics from animals safe to take?
Animal-derived probiotics can be safe, but it depends on the specific strain. A 2026 study found that two of eight pig farm bacteria strains were safe with no dangerous genes, while one carried transferable antibiotic-resistance genes. Always check if the product has undergone whole-genome safety testing.
Can probiotics give me antibiotic resistance?
Some probiotics could theoretically transfer antibiotic-resistance genes to your gut bacteria, though this risk varies by strain. Research shows certain strains like E. faecium F130 can transfer resistance genes, while others like P. pentosaceus R124 cannot. Choose products with proven genetic safety.
What makes a probiotic actually work in your stomach?
Effective probiotics must survive stomach acid and stick to intestinal cells. The 2026 study found L. plantarum Z108 survived at pH 2.0 with 24.18% survival rate, while P. pentosaceus R124 achieved 54.11% adhesion to intestinal cells—both key functional markers.
How do I know if a probiotic is safe before buying it?
Look for products that display whole-genome sequencing safety results showing no acquired antibiotic-resistance genes or virulence factors. Avoid E. faecium strains unless the manufacturer proves the specific strain is safe. Ask manufacturers for genetic safety data before purchasing.
Which probiotic strains are safest according to recent research?
A 2026 study identified P. pentosaceus R124 and L. plantarum Z108 as the safest candidates, showing strong probiotic function with no dangerous genes. E. faecium F130 posed safety risks due to transferable antibiotic-resistance genes and should be avoided unless specifically safety-tested.
Want to Apply This Research?
- Log the specific probiotic strain name and manufacturer weekly, and track digestive symptoms (bloating, regularity, energy levels) on a 1-10 scale to monitor personal response while ensuring you’re using a safety-tested strain.
- Switch to probiotic products that display whole-genome sequencing safety data on their labels or websites, and photograph or save this safety information in your app for reference when discussing probiotics with your doctor.
- Set a quarterly reminder to review your probiotic choice against updated safety databases, and track any changes in how your body responds to help identify if a strain is working for you personally.
This research examines laboratory-tested bacterial strains and does not constitute medical advice. Probiotic supplements are not regulated the same way as medications by the FDA. Before starting any probiotic supplement, especially if you have a weakened immune system, are pregnant, nursing, or taking antibiotics, consult with your healthcare provider. This study was conducted in laboratory conditions and may not reflect real-world outcomes in human digestive systems. Individual results vary, and what works for one person may not work for another.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.