Over the years, probiotic formulations have typically relied on oxygen-tolerant bacteria such as Lactobacillus and Bifidobacterium, primarily because these strains can survive the standard manufacturing process. Although they generally provide clinical benefits, these strains alone do not fully reflect the bacterial species that characterize a healthy, stable gut microbiome.
Many of the bacteria The gut flora most commonly associated with a healthy, resilient gut microbiome are considered keystone commensals. These organisms play an important role in maintaining microbiome stability through functions such as Short-chain fatty acid production, mucin support, and metabolic cross-feeding with other beneficial microbes. Several important commensal species, including Faecalibacterium prausnitzii (F. prausnitzii) and Roseburia intestinalis (R. intestinalis), are obligate anaerobes, meaning they cannot survive in the presence of oxygen.
Standard production of probiotics involves processes such as fermentation, harvesting, freeze-drying and encapsulation, all of which involve exposing bacteria to oxygen at some point. While oxygen-tolerant organisms can generally survive this process, obligate anaerobes such as F. prausnitzii and R. intestinalis cannot survive when exposed to oxygen and become useless during probiotic production. As a result, commercially available probiotics have historically excluded many important commensal organisms that help create a more complete and resilient intestinal ecosystem.
This manufacturing hurdle has important clinical implications. Faecalibacterium prausnitzii and Roseburia intestinalis are common lower values in people with inflammatory, metabolicAnd neurological diseases. At the same time, large microbiome studies have shown that these bacteria are common and stable components of a healthy intestine. Until recently, there was no practical way to incorporate them into a shelf-stable probiotic product. However, a patent-pending anaerobic production platform, Microbial Ecosystem Therapeutics (MET), is now beginning to address this limitation.
From FMT to MET
Fecal microbiota transplantation (FMT) is a procedure in which stool from a healthy donor is transferred into the intestines of a person with a disrupted microbiome. It was one of the first approaches to show that restoring a complete microbial community, including oxygen-sensitive anaerobes, can help restore balance to the gut. That was special effective in treating recurrences Clostridioides difficile (C. diff) infection. At the same time, FMT has significant limitations because it relies on donor stool, which can vary from sample to sample, and raises safety and regulatory concerns that make it difficult to standardize for wider use.
These limitations led to the development of Microbial ecosystem therapeutics (MET). Instead of transferring whole stool, MET isolates specific anaerobic strains from a single, rigorously screened donor and cultivates them under oxygen-free conditions. This results in a reproducible formulation that avoids many of the disadvantages and safety concerns associated with FMT. MET has demonstrated the ability to do this in early clinical trials Solve recurring ones C. difficile infection in patients who did not respond to standard therapies. Therefore, MET follows the same ecological approach as FMT, using cultured, standardized bacterial strains rather than relying on repeated stool transfers from donors.
What MET technology achieves
The key advance behind MET is the ability to culture and produce anaerobic bacteria under controlled, oxygen-free conditions throughout the production process. The finished product is used in packaging designed to limit exposure to moisture, oxygen and light, thereby maintaining shelf life even without refrigeration.
Beyond oxygen control, MET also focuses on the selection of cooperating organisms. Rather than combining unrelated strains, these formulations are based on the bacteria involved Cross-feeding networks and metabolic activity. This better reflects how these organisms behave in a healthy gut ecosystem.
Why these organisms are important
One of the most notable results of this approach is the ability to incorporate key commensal organisms that were previously unavailable in probiotic products. Typically, Faecalibacterium prausnitzii is responsible about 5% of the gut microbiota in healthy adults. Considering that the gut microbiome contains thousands of different species of microbes, this percentage represents a significant presence in the gut ecosystem. It is a major producer of butyrate, a short-chain fatty acid that plays a central role in supporting intestinal barrier integrity and immune regulation. Reduced abundance of this keystone species was observed under all conditions inflammatory bowel disease (IBD), Type 2 diabetes, severe depressive disorderAnd Parkinson’s disease.
Roseburia intestinalis is another important commensal probiotic that represents the following approximately 2 to 5% of an adult’s gut microbiota and is also considered a key species producing butyrate. It is reduced in a number of inflammatory and metabolic diseases including Ulcerative colitis, Crohn’s disease, obesity and type 2 diabetes. These organisms have been extensively studied but have not yet been able to be incorporated into probiotic formulations due to their sensitivity to oxygen.
With MET-based approaches, these key species can now be combined with other key organisms such as Akkermansia muciniphila, Bifidobacterium longum and Bifidobacterium jugendlichis. These organisms are involved in complementary metabolic pathways and mutual feeding relationships that help support the overall stability of the microbiome.
Summary
Many of the key commensal bacteria most strongly associated with a healthy, resilient gut microbiome have historically been excluded from commercial probiotics due to their oxygen sensitivity. Advances in anaerobic manufacturing, particularly through MET, now enable the reliable production and delivery of these organisms, including species such as F. prausnitzii and R. intestinalis, which were previously unavailable in probiotic formulations. This represents a major shift toward inclusion of clinically relevant anaerobic strains that previous manufacturing methods could not support.
Learn more about keystone commensals and the gut microbiome:
The Gut Ecosystem: Why Biodiversity Matters
What are important probiotic species?
The New Way to Support Gut Health: Keystone Commensal Probiotics
Not all probiotics are created equal
By Jesse Martin, MS
