Some bacteria are probiotic, namely Lactobacillus plants lp14, Lactobacillus curlatus LCRO4, and Lactobacillus acidophilus LA12, is able to varying degrees to detoxify cadmium, lead and other toxic metals. These microbial allies may also be able to ameliorate intestinal epithelial damage caused by heavy metal exposure.
Those are the main signals from New paper Published in Frontiers in microbiology.
Although the notes were from In the laboratory Experiences and not alive
When tested in humans, they provide strong proof of concept that some microbes can sequester and detoxify toxic metals, and that they have the potential to reduce the toxicity associated with heavy metals (HM) that we humans absorb through our food and water.
“Taken together, our findings demonstrate that probiotic-mediated intestinal bioremediation is a feasible and promising strategy to counter heavy metal exposure,” says the microbiologist. Marco Pan, Ph.Dwho was the principal investigator of the new study.
Pan is the Chief Science Officer at Probiotics, an Italian company focused on developing probiotic strains for use in human health and nutrition products. Probiotics sponsored the new study, which was conducted in collaboration with researchers at Ghent University and Piedmont Orientale University.
“Taken together, our findings demonstrate that probiotic-mediated intestinal bioremediation is a feasible and promising strategy to counteract heavy metal exposure.”
-Marco Pan, Ph.D., Chief Science Officer, Probiotics
“It is interesting to note that many… L plants Strains elsewhere have been reported to absorb and immobilize heavy metals. Our results are consistent with these reports, and even suggest that dietary consumption of… L plants“Rich fermented foods (eg, traditional sauerkraut or other lactofermented vegetables) combined with a potentially contaminated meal (eg, a fish dish high in HMs) can help reduce the absorption of HMs in the gut,” Pan and colleagues wrote.
Towards bioremediation
The three organisms – LP14, LA12 and LCR04 – analyzed in the current study were selected based on a previous study. In the laboratory An experiment in which each microbe was exposed to a mixture of four HMs, namely cadmium and Cd2+
(1.1 mg/L), Chromium Chromium3+ (17.6 mg/L), Hg2+
(8.8 mg/L), and lead (Pb).2+ (14.9 mg/L). There were two parts to the test: in the first, insects were incubated with the HM mixture, while in the second they were cultured in HM-free medium, with the toxin mixture added afterwards.
All three of these well-characterized gut-derived lactobacilli have shown the ability to sequester and detoxify metals to varying degrees.
For the current experiments, Pan and his research team used Simulating the Human Intestinal Microbial Ecosystem (SHIME), Which depicts conditions inside the human stomach, small intestine and colon. The SHIME simulator allowed investigators to test for high levels of cadmium, lead, chromium, mercury and other metals that would be toxic to actual humans.
For these tests, the SHIME platform was configured for a dynamic representation of the upper gastrointestinal tract, followed by short-term colon simulation under feeding conditions. Survival, growth, and heavy metal detoxification capacity of each strain were evaluated under sequential stomach, small intestine, and colon conditions.
SHIME enabled Pane and his team to evaluate and compare the three microbes, measuring their relative relevance to the sequestration of specific minerals.
The colonic phase is key
They found it L plants LB14, W L. Crispatus LCRO4 showed a strong ability to reduce the bioavailability of toxic metals, but only in the colonic phase of the SHIME mimetic. in contrast, L. acidophilus LA12 They showed only a small – albeit measurable – ability to remove toxins.
All three Lactobacillus strains maintained high cell numbers by mimicking the small intestine (biliary and pancreatic enzymes), suggesting that they can indeed withstand the biochemical stresses of small intestinal conditions. But they did not show any HM detoxification activity in the small intestine of the simulator.
Mechanistically, only strains that propagated well in the colonic stage achieved significant HM removal.
“For all strains, quantitative analyzes revealed that samples from the simulated end-ileal environment showed HM levels very similar to the empty conditions (where the reactor was filled with HMs and no bacteria were added to them), suggesting that the small intestine conditions did not enable HM detoxification,” they wrote.
They add that L. Acidophilus LA12, which thrives in small intestinal conditions, and does not reproduce well in colon conditions, which may explain its minimal ability to remove metal toxins.
Metal differences
Researchers noted breed-specific and mineral-specific differences. Both the LP14 and LCR04 were able to detoxify lead, cadmium, chromium, and lead to some extent. But LCR04 showed a special affinity for lead, reducing the amount of lead in the supernatant by about 45%. Both microbes were able to reduce cadmium and chromium by 20-40%.
“Mercury was the most rebellious metal,” Pan notes. LP14 and LCR04 were able to detoxify only about 10% of the mercury present in the test mixture.
It is well established that HM exposure can negatively affect intestinal mucosal integrity and intestinal homeostasis. Although these effects vary depending on the type and concentration of the metal, all heavy metals have an irritant effect on the intestinal epithelium, leading to tissue stress and inflammation, and altering the composition of the microbiome.
Mucosal protective effects
To evaluate whether probiotics are in fact able to protect the gastrointestinal mucosa from tissue damage caused by heavy metals, Pan and his group followed up their SHIME simulation studies with an experiment using the gastrointestinal tract. Previous living Jeffs system.
This system used small intestines removed from freshly killed 13-day-old mice and implanted in silicone intestines. ex vivo
system, with serum-free tissue culture medium. The intestine was passed through six independent chambers, each chamber connected to two needles connected to input and output syringes. This allows precise control of the flow of the nutrient medium into the internal intestinal chamber.
At high concentrations, heavy metals tend to be very damaging to the intestinal mucosa. Pan’s team initially tested the concentrations of HM used in the initial screening and SHIME experiments, but they found that at these levels the metals caused so much damage that intestinal tissue was no longer viable.
“Tissues treated with probiotics showed an attenuated inflammatory response and preservation of epithelial integrity compared to tissues exposed to HMs alone.”
They ended up testing lower concentrations of HM (0.69 mg/L Cd2+31.2 mg/L chromium3+5.2 mg/L mercury2+and 6.9 mg/L of lead2+), which had a significant effect on mucosal permeability but without destroying tissue vitality.
In the ex vivo mouse intestinal system, even these relatively low concentrations compromised epithelial barrier integrity and elicited pro-inflammatory responses.
Preincubation of HMs with each of the three probiotic strains significantly attenuated these effects and restored normal intestinal permeability and cytokine profiles to some extent.
“Tissues treated with probiotics showed an attenuated inflammatory response and preservation of epithelial integrity compared to tissues exposed to HMs alone.”
This experiment tested a mixture of fixed proportions of minerals and therefore sheds little light on the specific mucosal effects of any one of them. The experimental design did not allow researchers to determine whether the protective effect was due to the ability of probiotics to sequester harmful metals, or whether it was a byproduct of bioactive substances secreted by microbes that might enhance mucus barrier function or downregulate inflammatory signals.
These questions, Baney says, still need to be explored in future studies.
Chronic exposure to HM tends to reduce the relative abundance of Firmicutes and Proteobacteria, while enhancing the growth of bacterial populations. Functionally, these disorders can negatively impact the integrity of the intestinal barrier.
Although limited, current observations show that probiotics can reduce the toxic effect of HMs on intestinal tissue. Pan speculated that this occurs “most likely through decreased bioavailability of minerals.”
Two-way relationship
There are a number of mechanisms by which probiotics such as the three tested in these studies can mitigate HM toxicity. These include: direct linkage to HM; The chelation process is complicated. Intracellular accumulation. The enzymatic or chemical modification of metals by oxidation, reduction, or demethylation.
Dr. Pan describes the relationship between heavy metal pollutants and gut microbes as “bidirectional.”
Clearly, exposure to metals can alter the composition and function of the microbiome. For example, chronic exposure to HM tends to reduce the relative abundance of HM Firmicutes and Proteobacteriawhile promoting growth Bacteroidetes Population. Functionally, these disturbances can negatively affect the integrity of the intestinal barrier and alter the composition of short-chain fatty acids produced by the microbiota.
But, as clearly shown in the PANI experiments, some gut-derived microbes can alter the toxicity of problematic HMs, reducing their negative impact on gut physiology. This is the basic principle of bioremediation.
There are clear limitations to Pan’s studies. First, they are funded by (probiotic) companies and therefore may contain biases in favor of patented probiotic strains. Since no other probiotic species or strains were tested, the data cannot be generalized beyond the three strains used in the trials.
Secondly, this is at an early stage, In the laboratory Experiments, not human clinical trials – or even alive Animal studies. It remains to be determined whether the mitigating effects of metals can actually occur in living organisms.
Ban acknowledges that “the absence of… alive
The data limit the translational generalizability of the results, especially with regard to systemic outcomes and long-term efficacy.
However, he emphasized that “these limitations do not detract from the novelty and importance of the study but rather highlight the need for cautious interpretation.”
“Exposure to heavy metals is a chronic public health condition that source control cannot solve at the population level. Enteral bioremediation is the missing part of the food safety chain,” Dr. Pan said. He said on the NutraIngredients website. “We now have the scientific basis to move forward with clinical research.
In the future, he and his team plan to test HM probiotic therapy in animals, hoping to confirm the compelling phenomena they have observed in In the laboratory Experiments. The ultimate goal, he says, is to bring this into the real clinical world as “a more natural, proactive and less invasive way to reduce the health risks associated with environmental heavy metal burdens.”
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