Research in synthetic biology opens up new perspectives on the understanding and manipulation of life forms. “Mirror life” – a synthetic organism, whose molecular appearance would reflect natural life – currently seems impossible. And so far, that's the case – even the simplest mirror bacteria would be far too complex for scientists to attempt to create. But it is causing growing concern. These mirror bacteria, by escaping natural immune mechanisms, could represent an unprecedented threat to ecosystems and public health.
A recent study, led by 38 scientists from renowned institutions such as the University of Pittsburgh, the University of Manchester and the Pasteur Institute, warns of the potential dangers of this research. Published in the journal Science, this analysis calls for a global debate to regulate the development of these organisms before they pose uncontrollable risks. This position underlines the urgency of rigorous ethical and scientific supervision.
A scientific innovation that is still conceptual
First, let's define what these mirror bacteria are. These are hypothetical organisms designed from inverted chiral molecules. Why hypothetical? Because they haven't been created yet. They are a conceptual projection based on theoretical and technical advances in synthetic biology.
Let’s return to the notion of chirality. In nature, proteins and sugars follow a specific orientation, essential for their biological interaction. Proteins are composed of “left-handed” amino acids, while sugars adopt a “right-handed” configuration. Reversing this chirality would result in fundamentally distinct organisms. They would be incapable of biological dialogue with natural life forms. As the report states, these bacteria could be recognized neither by the human immune system nor by typical microbial predators, such as phages and protists. This radical biological compartmentalization would make these entities potentially invisible and invulnerable to natural control and regulation mechanisms.
Currently, no living organism consisting solely of molecules of inverted (or mirror) chirality exists. Neither nature nor in laboratories. Certainly individual mirror molecules, such as proteins or inverted nucleic acids, were synthesized for specific studies. But assembling these molecules into a functional cell remains a major technical challenge.
Creating a mirror bacteria would require overcoming several scientific obstacles, including the synthesis of complex biological structures such as mirrored ribosomes, and their integration into a functional living system. However, rapid progress in synthetic biology makes this scenario plausible in the medium to long term. It is this future possibility that raises concerns and motivates calls for caution, even though these bacteria do not yet exist.
Potential risks not yet measured
The risk goes beyond the simple inability of the immune system to respond. Mirror bacteria could theoretically adapt to natural environments by exploiting nonchiral nutrients, such as glycerol, or modified molecules to meet their needs. Without natural predators to limit their spread, they could proliferate uncontrollably in various ecosystems, leading to major ecological imbalances.
Natural proteins are exclusively left-handed © Tadashi Ando from TUS
At the same time, human infections could reach catastrophic levels due to the inability of antibodies to recognize their reverse targets, a phenomenon comparable to artificially induced immunodeficiency. These perspectives explain why many researchers are calling for a moratorium on this work. They currently consider them too risky to be pursued without strict supervision.
An international response to prevent the risks of mirror bacteria
The analysis published in Science constitutes an unprecedented collective position regarding the risks associated with mirror bacteria. This 300-page report, drawn up by a group of 38 scientists from nine countries, sounds the alarm about the dangers involved in this research. Among the signatories are renowned figures such as Nobel Prize winners Greg Winter and Jack Szostak, as well as specialists in immunology, ecology, and bioethics.
Faced with the risk of propagation without possible control, the report recommends an immediate moratorium on their development. He urges funding institutions to stop supporting these projects as long as tangible evidence of their safety remains absent. This plea also emphasizes the urgency of a public and scientific debate to rigorously regulate the implications of these technologies.
Nevertheless, scientists recognize the value of mirror molecules beyond the creation of entire organisms. These synthetic molecules, which include proteins or nucleic acids with reverse chirality, could transform the medical field. Their inability to interact with normal biological mechanisms would make them promising tools for the treatment of complex diseases. Particularly in cases where current immune responses limit the effectiveness of conventional therapies.
Drugs based on these molecules could resist enzymatic degradation processes. This would actually prolong their effectiveness in the body. The signatories of the report insist that this research must continue within a strictly defined framework. We must avoid any shift towards the manufacture of mirror bacteria, the implications of which would exceed current control and risk management capacities.
Mirror bacteria providing opportunity for global dialogue
The risks associated with mirror bacteria have sparked a call for global action. It becomes necessary to supervise research in this area before it poses uncontrollable threats. In response, a series of international conferences and meetings are planned in 2025. Notably at the Pasteur Institute in Paris, the University of Manchester and Singapore. These events aim to bring together scientists, policy makers, funding institutions and representatives of civil society.
The aim is to establish ethical standards and clear regulatory frameworks. The objective is to anticipate potential dangers while opening a space for discussion on the benefits and limits of this technology. Patrick Cai, professor of synthetic genomics at the University of Manchester, said these discussions provide a rare opportunity to act proactively. These meetings should make it possible to reconcile the pursuit of scientific advances with responsible risk management.
This initiative also seeks to strengthen international cooperation. It is essential to establish consensus on the priorities and limits of synthetic biology research. The technologies resulting from this work, such as mirror molecules for therapeutic or industrial applications, are seen as promising. In bioproduction, these molecules could offer systems more resistant to contamination, thus improving the efficiency of industrial processes. By instituting safeguards now, scientists hope to capitalize on potential benefits, preventing high-risk scenarios. This should ensure balanced and secure development of these technologies.
Source : Katarzyna P. Adamala et al., “Confronting the risks of mirror life”, Science (2024).
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