Researchers call for global discussion about possible risks from “mirror bacteria”

A group of researchers has published new findings in Science on potential risks from the development of mirror bacteria — synthetic organisms in which all molecules have reversed chirality (i.e. are ‘mirrored’).

Scientists had begun early work toward creating mirror bacteria, and while the capability is at least a decade away, recent years have seen significant progress. The new paper finds that, if created, these organisms may pose significant dangers to human, animal, plant, and environmental health. The authors call for a broad conversation among scientists, policymakers, and a wide range of other stakeholders to chart a path towards better understanding and mitigation of potential risks from mirror bacteria.

The 38 authors working in nine countries include leading experts in immunology, plant pathology, ecology, evolutionary biology, biosecurity, and planetary sciences. The publication in Science is accompanied by a detailed 300-page technical report.

While any threat is not imminent, the Science paper finds that mirror bacteria may pose serious risks. Immune defenses in humans, animals, and plants rely on recognizing specific molecular shapes found in invading bacteria. If these shapes were reflected — as they would be in mirror bacteria — recognition would be impaired and many basic immune defenses could fail, potentially leaving organisms vulnerable to infection.

The analysis also suggests that mirror bacteria in the environment may be able to evade natural predators like phages and protists, which rely heavily on chirally-mediated interactions to kill bacteria and limit their populations. Transport via animals and humans could enable spread between diverse ecosystems. Persistent and widespread environmental populations of mirror bacteria would expose humans, animals and plants to an ongoing risk of infection — a serious threat to humans and to global ecosystems.

The authors call for further scrutiny of their findings and conclude that, unless compelling evidence emerges that these organisms would not pose extraordinary dangers, mirror bacteria should not be created. Notably, the group includes several authors who previously held the creation of mirror bacteria as a long-term aspirational goal.

This paper marks a starting point for a broader discussion about the risks from mirror bacteria, including participation from the global scientific community, policymakers, research funders, and other stakeholders. Several of the authors on the paper are involved in planning a series of events throughout 2025, including events planned at the Institut Pasteur in France, the University of Manchester in the U.K. and the National University of Singapore, to scrutinize the findings of the paper and discuss steps that can be taken to prevent risks from mirror bacteria.

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