A summary of: Lerner et al., “Genetically Modified Microorganisms: Risks and Regulatory Considerations for Human and Environmental Health,” Microorganisms, 2026. https://doi.org/10.3390/microorganisms14020467
This summary is based on a peer-reviewed paper co-authored by Andre Leu, International Director of Regeneration International, a global nonprofit network dedicated to promoting regenerative agriculture and land management practices. Leu is a longtime advocate for organic farming and soil health, and has written extensively on the risks of pesticides and industrial agriculture. His involvement in this paper reflects Regeneration International’s broader mission to protect the biological integrity of soils and ecosystems, concerns that are central to the study’s findings on GMMs and the soil microbiome.
The Big Picture
When most people hear “GMO,” they think of crops – corn or soybeans engineered to resist pests. But scientists have been quietly engineering something far smaller and potentially far more consequential: microorganisms. Bacteria, yeasts, and fungi have been genetically modified and, in some cases, released into the environment on a massive scale, sometimes without the public even knowing.
A new review article published in the journal Microorganisms by a team of eight scientists and physicians argues that we are moving too fast. The technology to create genetically modified microorganisms (GMMs) has outpaced the regulations designed to keep them in check, and the potential consequences, for human health, for soil, and for the climate, deserve urgent attention.
What Is a Genetically Modified Microorganism?
A microorganism (or “microbe”) is any living thing too small to see with the naked eye: bacteria, viruses, fungi, and more. A genetically modified microorganism is one whose DNA has been intentionally altered in a lab, often using tools like CRISPR-Cas9, a kind of molecular “cut and paste” that can add, remove, or rewrite genetic instructions.
GMMs are not new. Since the 1980s, engineered bacteria have been used to produce human insulin, which transformed diabetes treatment. But the technology has become dramatically cheaper and more accessible. Today, CRISPR kits are available online, and high school students are creating novel microbes in classroom experiments.
The global market for GMMs used in agriculture alone was valued at over $10 billion in 2021 and is expected to nearly triple by 2029.
Why Microbes Are Different, and Potentially More Risky
The authors point out five features of microbes that make them uniquely challenging to regulate compared to genetically modified plants or animals:
- They reproduce extremely fast. Under ideal conditions, a single bacterium can double its numbers every 20 minutes. An engineered trait can spread through billions of organisms in hours.
- They’re nearly impossible to contain. Microbes travel on wind, water, animals, and people, reaching distant ecosystems and hosts.
- They share genes with each other. Through a process called horizontal gene transfer, microbes can pass genetic material to other, completely unrelated, microbes. An engineered gene could end up in microbes that were never modified in the first place.
- Microbiomes are essential to life. The communities of microbes living in and around humans, animals, plants, and soils are not just passengers, they are vital to health, immunity, and ecological balance.
- We know very little about them. Scientists estimate there are roughly one trillion different microbial species on Earth. We’ve only identified and characterized about 1% of them.
What Could Go Wrong? Key Risk Scenarios
The paper walks through several concrete scenarios where GMMs could cause harm.
Your Baby’s First Microbiome
The first three years of a child’s life are a critical window for establishing the gut microbiome, the community of microbes that shapes immune development, brain development, and lifelong health. A baby’s microbiome is seeded from the mother: through vaginal birth, breastfeeding, and skin contact.
The authors raise concern that GMMs could interfere with this delicate transfer. A genetically modified microbe could colonize a mother’s gut, mouth, vagina, or breast tissue, and then pass to her infant. The authors note that babies born by C-section, who miss out on vaginal microbiome transfer, already face higher rates of asthma, allergies, celiac disease, and diabetes. Anything that further disrupts microbial inheritance could have lasting consequences. Yet there is currently no research on how GMMs might affect breast milk, pregnancy outcomes, or infant microbiome development.
Your Mouth: A Highway for Gene Transfer
The oral microbiome, the 770-plus species of microbes living in your mouth, plays a surprising role in whole-body health. Friendly oral bacteria contribute up to 25% of your daily production of nitric oxide, a molecule essential for healthy blood pressure. An imbalanced oral microbiome has been linked to increased risk of heart attack, brain inflammation, diabetes, lung infections, and even preterm birth.
The mouth is also a prime location for horizontal gene transfer, meaning it’s a place where engineered genes could easily spread to other microbes. If a GMM displaced beneficial bacteria or shared genes with harmful ones, the downstream effects could be significant and very difficult to reverse.
An Industrial Yeast That Could Trigger Gut Infections
One of the more detailed examples in the paper involves a yeast called Yarrowia lipolytica, which has been widely engineered in industrial settings to produce various compounds. In one application, it was modified to consume a common sugar (xylose, found in fruits, bread, and many processed foods) and produce large amounts of succinate, a chemical normally present only in small quantities in the gut.
The problem: high succinate levels are known to trigger overgrowth of Clostridium difficile (C. diff), a bacterium responsible for severe, potentially life-threatening diarrhea. If engineered Y. lipolytica were to accidentally escape containment and colonize the human gut, particularly in vulnerable people like newborns, premature infants, or immunocompromised patients — it could set the stage for dangerous infections.
A Food Additive Enzyme That May Trigger Autoimmune Disease
An enzyme called microbial transglutaminase (mTg) is widely used in the food industry to improve the texture of processed meats, dairy, and baked goods, essentially acting as a “protein glue.” It’s produced using genetically modified bacteria and is present in countless processed foods worldwide. The global market for mTg was valued at $136 million in 2024, growing rapidly.
The authors argue the safety status of this enzyme deserves serious reconsideration. Unlike the human body’s own transglutaminase enzyme, mTg lacks the usual biological “off switches.” It can operate across a wider range of conditions, penetrate tissue more readily, and form chemical bonds that are highly resistant to the body’s normal breakdown processes.
Research has linked mTg to increased intestinal permeability (sometimes called “leaky gut”), celiac disease, autoimmune conditions, and potentially neurodegenerative diseases. Regulatory bodies in Switzerland, Germany, and Canada have already issued warnings, yet mTg continues to be used in processed foods globally with limited oversight.
Soil Microbes: The Foundation of All Life, and Climate Stability
Perhaps the most sweeping concern in the paper is about soil. One teaspoon of healthy soil contains billions of microbes. These microbes break down organic matter, cycle nutrients, and, critically, sequester carbon dioxide from the atmosphere. Soils hold more carbon than all plants and the atmosphere combined.
GMMs are already being released into agricultural soils at enormous scale. One company has spread its genetically engineered bacteria across nearly 5 million acres of farmland, releasing as many as 5 trillion microbes per acre. Another product covers 10 million acres and counting.
The authors warn that introducing engineered microbes into soil ecosystems, which are already stressed by climate change and industrial agriculture, could have cascading effects. Genetically engineered microbes could transfer their genes to native soil bacteria, creating new organisms with unpredictable traits. They could disrupt the delicate microbial processes that stabilize carbon in the soil. They could pave the way for “super bugs”, highly adapted, resistant microbes — just as herbicide-resistant “super weeds” emerged after widespread use of GM crops.
The Regulatory Gap
In the United States, GMMs used commercially are primarily regulated by the Environmental Protection Agency (EPA), under laws designed for toxic chemicals, not living, self-replicating organisms. Most GMMs not intended for commercial sale are effectively unregulated and untracked.
Meanwhile, many countries including the US, UK, Canada, and Australia have been deregulating gene-edited organisms, particularly those that don’t introduce DNA from another species. The authors argue this creates a dangerous blind spot, since gene editing can still cause unpredictable genetic changes, large deletions, chromosomal rearrangements, and unintended mutations, whether or not foreign genes are introduced.
As the U.S. Department of Homeland Security has acknowledged, the speed of innovation has outpaced American regulatory policy, and that gap needs to close.
What the Authors Are Calling For
The researchers propose a structured “biosafety workflow”, essentially a checklist of questions that should be answered before any GMM is created or released:
- What is the GMM’s intended function, and are there safer alternatives?
- What are the potential routes of escape or spread?
- How might the GMM interact with human microbiomes?
- What are the risks to soil, water, and wild ecosystems?
- What monitoring will occur after release?
Above all, they urge regulators to adopt the precautionary principle, the idea that when something carries significant potential for irreversible harm, the burden of proof should fall on demonstrating safety before release, not after. (See link for article)
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