“This technology provides a new paradigm for rapid and non-invasive detection of gastrointestinal diseases,” says Ying Zhou, a co-author of the study.

Why Easier, Noninvasive Gut Diagnostics Are Needed

In the U.S., millions of people live with colorectal cancer or inflammatory bowel disease, including colitis, which can lead to intestinal bleeding, diarrhea and abdominal pain. Colonoscopy remains the gold-standard diagnostic tool. It relies on an endoscope, a camera-tipped flexible device that is carefully guided through the large intestine. Although it provides valuable medical insight, many individuals hesitate to undergo the procedure because it requires extensive preparation and can feel invasive. To develop an alternative, Zhou, Bang-Ce Ye, Zhen-Ping Zou and colleagues are exploring the use of bacteria that detect biomarkers such as heme, a component of red blood cells that signals bleeding inside the gut.

Building Bacterial Sensors That Survive Digestion

The team previously designed bacteria that emit light when they encounter heme, but the early versions broke down during digestion and were difficult to retrieve afterward. In the new study, the researchers protected the bacteria by enclosing them, along with magnetic particles, inside small droplets of sodium alginate, a thickening ingredient commonly found in foods. This produced sturdy hydrogel microspheres that travel through the digestive tract and can be removed from stool with a magnet. Initial laboratory tests confirmed that the hydrogel shield allowed the bacteria to survive simulated digestive conditions while still letting heme reach the sensor and trigger a glow.

Testing the Microspheres in Mouse Models of Colitis

The researchers then gave the microspheres orally to mice with varying levels of colitis, ranging from no disease activity to severe inflammation. After the spheres moved through the gastrointestinal tract, the team retrieved them using a magnet and reported three key findings:

• Microsphere cleanup and signal analysis required about 25 minutes.
• The sensors produced stronger light signals as disease severity increased, indicating higher levels of heme in animals with more advanced colitis.
• Tests in healthy mice showed that the microspheres were biocompatible and safe.

Future Potential for Human Testing and Disease Monitoring

Although the technology has not yet been evaluated in humans, the researchers suggest that encapsulated bacterial sensors could one day help diagnose gastrointestinal diseases, monitor treatment responses and track changes in disease over time.

The authors acknowledge funding from the National Natural Science Foundation of China, the National Key Research and Development Program of China, and the China Postdoctoral Science Foundation.

The work appears in the article titled ‘Safeguarding Microbial Biodiversity: Microbial Conservation Specialist Group (MCSG) within the Species Survival Commission of the International Union for Conservation of Nature (IUCN)’, published in Sustainable Microbiology, an AMI journal.

Launching a New Global Effort Through the IUCN

In July 2025, the IUCN formally created the MCSG within its Species Survival Commission. The group is co-chaired by Professor Gilbert and Raquel Peixoto (KAUST / ISME). Its formation followed a May workshop led by Professor Gilbert that brought together conservation specialists and microbiologists to explore how traditional conservation goals apply in a world driven by microbial processes.

“This is the first global coalition dedicated to safeguarding microbial biodiversity, which is the ‘invisible 99% of life’, to ensure that microbes are recognized as essential to the planet’s ecological, climate, and health systems,” Professor Gilbert said.

He added: “I think this reframes conservation from saving individual species to preserving the networks of invisible life that make visible life possible — a paradigm shift toward planetary health. It also gives us a really good look into the microbial tools that can support conservation action — so that we may use microbiology to solve the world’s biggest problems.”

Why Microbial Biodiversity Matters for the Planet

Microbes are central to soil fertility, carbon cycling, marine productivity, and the health of plants and animals. Despite this, they rarely appear in conservation policy. Professor Gilbert noted that overlooking microbial diversity weakens climate resilience, food security, and ecosystem restoration efforts. He explained: “The MCSG fills this gap by embedding microbiology directly into IUCN’s conservation machinery, i.e. using Red List criteria, ecosystem assessments, and restoration programs, to make microbes visible in policy, not just in science.”

Building a Global Network to Guide Microbial Conservation

Over the past two years, the founding members have assembled an international community of microbiologists, ecologists, legal experts, and Indigenous knowledge holders from more than 30 countries. Together, they created the first microbial conservation roadmap, outlining five core components of the IUCN Species Conservation Cycle:

• Assessment — develop Red List-compatible metrics for microbial communities and biobanks.
• Planning — create ethical and economic frameworks for microbial interventions.
• Action — pilot restoration projects using microbial solutions (coral probiotics, soil carbon microbiomes, pathogen-resistant wildlife).
• Networking — connect scientists, culture collections, and Indigenous custodians worldwide.
• Communication & Policy — launch public and policy campaigns, including “Invisible but Indispensable.”

Early work is supported by funding from the Gordon & Betty Moore Foundation, along with in kind support from AMI and ISME. This first phase focuses on mapping microbial hotspots, building conservation indices, and linking existing microbial biobanks into a coordinated global archive.

Overcoming Scientific and Ethical Challenges

Professor Gilbert explained that creating a conservation framework for microscopic life comes with complex scientific and conceptual barriers. These challenges include:

• Determining what qualifies as a “microbial species” within Red List criteria.
• Integrating genomic and ecological information into systems originally developed for plants and animals.
• Addressing the belief that microbes are too resilient or too complicated to require protection.

“Microbial conservation must contend with enormous unseen diversity and highly dynamic community structures that defy classical species concepts. Taxonomic instability, lack of long-term baselines, and the ethical handling of microbial samples (including Indigenous or human-associated microbiota) all require new definitions of ‘loss’, ‘restoration’, and ‘rights of microbes’,” he said.

He added, “But a major landmark came when the IUCN approved the MCSG as a formal Specialist Group — officially extending global conservation to microbes for the first time.”

Plans for the Next Phase of Conservation Work

The group’s upcoming goals include:

• Developing the first Microbial Red List framework by 2027.
• Creating global maps of microbial hotspots across soil, marine, and host-associated systems.
• Testing conservation strategies such as microbial bioremediation, coral probiotics, and soil carbon restoration.
• Ensuring microbial indicators are incorporated alongside plants and animals in IUCN and UN biodiversity targets by 2030.

What Is Needed for Long-Term Progress

Sustained investment will be essential to expand global microbial monitoring networks. Future progress also depends on integrating microbes into national biodiversity and climate strategies, including “30 by 30” and One Health policies. Another key priority is building “public microbial literacy — recognizing microbes as the foundation of ecosystem and human health.” The roadmap also highlights the importance of digital-twin and AI tools to anticipate how microbial communities will respond to environmental change.

The paper was published today (November 20) in Sustainable Microbiology.