A group of researchers that includes Michigan State University faculty called attention to potential risks to humans and global ecosystems from the development of mirror bacteria — synthetic organisms that at the molecular level are ‘mirror’ versions of those found in nature.

Scientists have begun early work toward creating mirror bacteria. While the capability is at least a decade away, recent years have seen significant progress. The researchers published a new paper in the journal Science finding 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 toward better understanding and mitigation of potential risks from mirror bacteria.

Representing nine countries, the 38 authors of the Sciencepiece include leading experts in immunology, plant pathology, ecology, evolutionary biology, biosecurity and planetary sciences. MSU faculty Richard Lenski and James Tiedje are among the authors. Lenski is a John A. Hannah Professor in the Department of Microbiology, Genetics and Immunology and a core member of the Ecology, Evolution and Behavior Program. Tiedje is a University Distinguished Professor Emeritus in the Department of Plant, Soil and Microbial Sciences. Both are elected members of the National Academy of Sciences.

While a specific threat is not imminent, the Science paper, accompanied by a detailed 300-page technical report, 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.

According to Lenski, “The idea of creating mirror bacteria, where macromolecules like DNA and proteins are mirror images of those in nature, might seem like science fiction. But some scientists have been pursuing that goal, and it appears to be technically feasible. Fortunately, making mirror bacteria is at least a decade in the future, and maybe more, so we have time to carefully consider all the risks and discuss how best to avoid them.”

The analysis also suggests that mirror bacteria in the environment may be able to evade natural predators — including certain viruses and amoebas — which rely on interactions with the naturally configured molecules 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.

Another of the Science paper’s authors is Jack Szostak, a 2009 Nobel Laureate in Physiology or Medicine at the University of Chicago. “I was initially skeptical of the idea that mirror bacteria would be so dangerous,” Szostak said. “But after studying the issues, I now believe that mirror bacteria could spread across species and environments, resistant to predation and invisible to immune systems.”

“The first mirror bacteria, if they are created by responsible scientists, are likely going to be deliberately disabled, so they can’t grow outside the lab,” Lenski said. However, that might not be enough to ensure safety in the long run. “Once a mirror bacterium is created, it would become much easier for others to duplicate that feat. Someone or group might be tempted to produce a mirror version of a robust bacteria that would avoid natural controls and endanger humans and the environment. That’s the fear.”

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 paper’s authors are involved in planning a series of future events to scrutinize the findings of the paper and discuss steps that can be taken to prevent risks from mirror bacteria.

Read the Science Article and full technical report.