Scientists discovered that folic acid, an essential B vitamin, is accidentally being removed from laboratory growth media during sterilization, preventing them from growing most bacteria species. According to Gram Research analysis, this single problem likely explains why approximately 29% of all bacteria cannot be cultured in labs, and affects at least 76% of the 791 growth media recipes used worldwide. Fixing this issue by properly buffering vitamin solutions before sterilization could unlock cultivation of thousands of previously unculturable bacterial species.
Scientists have discovered a major reason why most bacteria can’t be grown in laboratory dishes: a common vitamin called folic acid is accidentally being removed during the sterilization process. Researchers studying unusual bacteria from hot springs and deep underground found that when they fixed this problem, they could finally grow these microbes in the lab. According to Gram Research analysis, this discovery suggests that at least three-quarters of bacterial growth media used worldwide may have the same hidden problem, which could explain why scientists have struggled to culture most bacterial species for decades.
Key Statistics
A 2026 research article published in Nature Communications found that approximately 29% of all known bacterial species require folic acid they cannot produce themselves, making them dependent on laboratory media containing this vitamin.
According to the 2026 study, at least 76% of the 791 bacterial growth media recipes in the MediaDive database use unbuffered vitamin solutions where folic acid is likely removed during filter-sterilization.
Gram Research analysis of the 2026 findings shows that 27% of entire bacterial phyla exhibit extensive folate auxotrophy, meaning they cannot synthesize folic acid and must obtain it from their environment.
The 2026 research identified that folate auxotrophy limits the culturability of bacteria across at least 604 of 791 media formulations, representing a systematic problem affecting microbiology laboratories worldwide.
The Quick Take
- What they studied: Why two newly discovered bacteria species from extreme environments were impossible to grow in laboratory culture media, and what this reveals about a widespread problem affecting bacterial cultivation worldwide.
- Who participated: Scientists isolated two new species of Caldatribacterium bacteria—one from a hot spring and one from a deep aquifer. The research involved analyzing genetic data from thousands of bacterial species and examining over 791 different growth media recipes used in laboratories.
- Key finding: Folic acid, an essential B vitamin, was being accidentally removed from laboratory growth media during filter-sterilization. This single problem likely prevents scientists from growing approximately 29% of all known bacteria species and affects at least 76% of media recipes that include folic acid.
- What it means for you: This discovery could unlock the ability to study and potentially use bacteria that scientists have never been able to culture before. However, this is primarily important for researchers and biotechnology companies rather than the general public at this stage.
The Research Details
Scientists used a genome-guided approach, meaning they analyzed the genetic blueprints of bacteria to predict what nutrients they would need to survive. They then tried to grow two newly discovered Atribacterota bacteria species in the laboratory using standard growth media recipes. When the bacteria refused to grow, the researchers investigated why, testing different components of the growth medium one by one.
They discovered that folic acid—a B vitamin added to the growth media—was being removed when the vitamin solution was filter-sterilized (a process that kills contaminating microbes by pushing the liquid through an extremely fine filter). The problem occurred because the vitamin solution wasn’t buffered, meaning it lacked chemicals to maintain the right pH level, causing the folic acid to precipitate (turn into solid particles) and get trapped in the filter.
Once they identified this problem, the researchers analyzed genetic data from thousands of bacterial species to predict which ones also needed folic acid to survive. They also reviewed a database of 791 different laboratory growth media recipes to determine how many had this same sterilization problem.
This research approach is important because it reveals a systematic, fixable problem that has been preventing scientists from studying most bacterial species. Rather than assuming bacteria are simply impossible to culture, this work shows that the problem may lie in how we prepare the growth media. Understanding this could revolutionize microbiology by making previously unculturable bacteria accessible for study.
This research was published in Nature Communications, one of the world’s most prestigious scientific journals. The findings are based on careful experimental work isolating new bacteria species, combined with comprehensive analysis of genetic data and existing laboratory protocols. The researchers’ discovery is reproducible—other scientists can test whether fixing the folic acid problem allows them to grow other bacteria species that previously wouldn’t grow.
What the Results Show
The researchers successfully isolated and grew two new Caldatribacterium bacteria species by ensuring folic acid remained in the growth medium during sterilization. These bacteria had been impossible to grow using standard laboratory techniques until this problem was identified and corrected.
Genetic analysis revealed that both newly isolated bacteria species require folic acid to survive—they cannot make this vitamin themselves and must obtain it from their environment. This trait, called folate auxotrophy, appears to be extremely common among bacteria.
When the researchers analyzed genetic data from thousands of bacterial species, they found that approximately 29% of all known bacteria likely cannot make their own folic acid and therefore need it supplied in growth media. This problem is even more severe in certain bacterial groups, with 27% of entire bacterial phyla showing extensive folate auxotrophy.
Most importantly, the researchers discovered that at least 76% of the 791 laboratory growth media recipes in a major database use unbuffered vitamin solutions, meaning folic acid is likely being accidentally removed during filter-sterilization in most laboratories worldwide.
The newly isolated Caldatribacterium bacteria also revealed unusual cellular structures. They possess three lipid membrane-like layers—structures that normally bacteria have only one of. The innermost layer surrounds the bacterial nucleoid (the region containing genetic material), which is an atypical arrangement. Additionally, these bacteria produce an unusually high percentage of secreted proteins, suggesting they have unique ways of interacting with their environment and other microorganisms.
This research explains a long-standing mystery in microbiology: why most bacterial phyla have few or no pure cultures despite being discovered in nature. Previous researchers assumed these bacteria were simply difficult or impossible to grow in laboratories. This work demonstrates that the problem may not be with the bacteria themselves, but with how scientists have been preparing growth media. The discovery aligns with growing recognition that many ‘unculturable’ bacteria may actually be culturable if their specific nutritional needs are met.
The study focused on two specific bacterial species from extreme environments (hot springs and deep aquifers), so results may not apply equally to all bacteria. The genetic predictions about folate auxotrophy are based on computational analysis of bacterial genomes and haven’t been experimentally verified for every species. Additionally, while the research identifies folic acid as one major problem, other nutrients or conditions may also prevent bacteria from growing in laboratory media. The study doesn’t address whether fixing the folic acid problem alone will allow all predicted bacteria to be cultured.
The Bottom Line
For laboratory scientists: Review your bacterial growth media preparation protocols, particularly how vitamin solutions are sterilized. Ensure folic acid solutions are properly buffered before filter-sterilization, or consider alternative sterilization methods. For researchers attempting to culture previously unculturable bacteria: Test whether supplementing growth media with properly preserved folic acid improves cultivation success. These recommendations are based on strong experimental evidence (high confidence).
Microbiologists and researchers attempting to culture bacteria in laboratories should immediately apply these findings. Biotechnology companies developing new bacterial strains for industrial use should review their media preparation. The general public should care because this breakthrough could eventually lead to new medical treatments, improved probiotics, and better understanding of environmental bacteria. However, practical applications for non-scientists are likely years away.
Scientists using corrected growth media protocols should see improvements in bacterial cultivation within weeks to months of implementing changes. However, developing practical applications from newly culturable bacteria (such as medical treatments or industrial processes) will likely take several years of additional research.
Frequently Asked Questions
Why can’t scientists grow most bacteria in the lab?
Scientists now know that folic acid, a B vitamin added to growth media, is accidentally being removed during sterilization. This affects about 29% of all bacteria species that cannot make their own folic acid. Fixing how vitamin solutions are sterilized could solve this widespread problem.
What is folate auxotrophy and why does it matter?
Folate auxotrophy means bacteria cannot produce folic acid themselves and must get it from their environment. This matters because approximately 29% of all bacteria have this trait, and if the folic acid in laboratory media is destroyed during sterilization, these bacteria cannot grow, preventing scientists from studying them.
How does filter-sterilization remove folic acid from growth media?
When vitamin solutions lack proper buffering (chemicals that maintain pH), folic acid precipitates into solid particles that get trapped in the filter during sterilization. Using buffered solutions or alternative sterilization methods prevents this loss and allows bacteria that need folic acid to survive and grow.
Could this discovery help develop new medicines or treatments?
Potentially yes. By making previously unculturable bacteria accessible for study, scientists could discover new antibiotics, probiotics, or industrial applications. However, this is early-stage research, and practical medical applications will likely take several years of additional development.
What unusual features did the newly discovered Caldatribacterium bacteria have?
These bacteria possess three lipid membrane-like layers instead of the typical one, with the innermost layer surrounding their genetic material. They also produce an unusually high percentage of secreted proteins, suggesting unique cellular biology compared to most other bacteria.
Want to Apply This Research?
- If you’re a researcher using this information: Track the percentage of bacterial species you successfully culture before and after implementing corrected folic acid protocols. Measure specific outcomes such as ’number of new bacterial isolates obtained per month’ or ‘success rate of cultivation attempts for target species.’
- For lab scientists: Create a checklist for media preparation that includes verifying folic acid buffer status before filter-sterilization. Set reminders to review media recipes quarterly and update protocols based on new research. Document which media formulations work best for your target bacteria species.
- Establish a long-term tracking system comparing cultivation success rates across different media preparations. Monitor whether newly culturable bacteria reveal additional nutritional requirements beyond folic acid. Track which bacterial phyla become culturable as these protocols are refined, building a database of successful cultivation conditions.
This research describes laboratory microbiology techniques and does not provide medical advice. The findings are primarily relevant to scientific researchers and laboratory professionals. While this discovery may eventually lead to new medical treatments or biotechnology applications, such developments are not yet available for clinical use. Individuals should not attempt to culture bacteria at home or modify laboratory protocols without proper training and facilities. Consult with qualified microbiologists or medical professionals regarding any health-related applications of this research.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.