Pause work on ‘mirror life’, recommends panel of international experts

Efforts to create ‘mirror life’ – life whose building blocks have the opposite handedness to life on Earth – should be halted, an international group of experts has recommended. The group warns that mirror microorganisms could potentially cause lethal infection in humans, animals and plants. While the ability to create such lifeforms is likely many years away, the researchers say that work towards making them should be stopped until there is ‘compelling evidence’ that they won’t cause harm.

All life on Earth shares the same chirality or handedness. Nucleic acids are right-handed, while proteins are left-handed. But some researchers want to create mirror life in which the chirality of biological molecules is reversed. The chirality of biomolecules matters as interactions between them relies on them having a complementary shape. Researchers have been interested in creating mirror life because of the possibility that it could result in organisms with different properties which might make them useful for certain applications, such as producing new therapeutics.

In a policy article published in Science, a group comprising Nobel laureates and experts from across the fields of synthetic biology, ecology, global health and policy, highlight that although a viable mirror microbe is likely to be ‘at least a decade away’, now is the time for broader discussion to ‘chart an appropriate path forward’.

The group of 38 experts includes the 2018 chemistry Nobel prize winner, Gregory Winter, Jack Szostak, who won the 2009 medicine Nobel prize and Craig Venter, the US scientist who led the private effort to sequence the human genome in the 1990s.

They explain that they have qualitatively assessed the feasibility and risks of creating mirror bacteria, considering factors such as the nature, magnitude and likelihood of potential harms; the ease of accidental or deliberate misuse; and the effectiveness of potential countermeasures. Although the focus of their assessment was on mirror bacteria, they said many of the considerations might also apply to other forms of mirror life.

Among the concerns raised was the risk that mirror bacteria would evade many immune mechanisms mediated by chiral molecules, potentially causing lethal infection in humans, animals and plants. ‘They are likely to evade predation from natural-chirality phage and many other predators, facilitating spread in the environment,’ the authors write. ‘We cannot rule out a scenario in which a mirror bacterium acts as an invasive species across many ecosystems, causing pervasive lethal infections in a substantial fraction of plant and animal species, including humans.’

Biocontainment and biosafety approaches could reduce these risks, they write, but escape from these safeguards through evolution or human error could still occur.

They concluded that the foreseeable benefits of the creation of mirror bacteria were ‘limited’ and that although mirror bacteria could be used to help manufacture unnatural biomolecules, such molecules could be made through other means.

‘We believe that it is important to begin a conversation on how the risks can be mitigated, and we call for collaboration among scientists, governments, funders, and other stakeholders to consider an appropriate path forward,’ they added.

Research to better understand and prepare for the potential risks – such as studying the interaction of mirror biomolecules with the immune system – is needed, they write, but overall they recommended that unless ‘compelling evidence’ emerged that mirror life would not pose a danger, mirror bacteria and other organisms should not be created.

Responding to the article, Ting Zhu, a biochemist at Westlake University in Hangzhou, China, who is working on mirror-image biological systems, told Chemistry World that although he supported the ‘cautious approach’ he didn’t think a complete mirror-image bacterium could be synthesised in the foreseeable future. ‘Creating a mirror-image (or even natural-chirality) cell from scratch would require unprecedented technologies and vast resources that are currently unavailable and unlikely to be available in the near future,’ he adds. ‘Meanwhile, it is imperative for scientists to be extremely cautious, avoiding the creation of living organisms of either chirality on this planet without ensuring total safety.’

The findings have also been released in an in-depth technical report. The group said they planned to convene discussions on the topic of mirror bacteria in 2025.

Update: The headline and first paragraph of this story were amended on 19 December 2024 for clarity. The description of Ting Zhu’s research interests was also clarified on 19 December 2024.