Scientific Dispute: The Risks of Lab-Engineered Bacteria in Mirror Life Research

Modeling studies indicate that microorganisms based on mirror images of natural molecules face significant survival challenges outside controlled laboratory environments. This raises questions about developed methods for “mirror feeding” or other innovative sustenance solutions.

However, the study has drawn criticism from experts in the field, who caution that it may overlook substantial risks associated with these so-called mirror organisms.

Many crucial biomolecules, like DNA and proteins, exhibit chirality, allowing them to exist as either left-handed or right-handed forms. Similar to the left and right hands, they are mirror images and cannot be superimposed. Presently, all known life on Earth utilizes right-handed DNA and left-handed proteins, enabling compatible interaction within cellular mechanisms.

While not technically feasible at this time, producing organisms with reversed chirality may one day become possible. In 2024, a collaboration of 38 scientists published research, calling for a halt on studies aimed at creating mirror life due to potential threats these organisms could pose—such as immune systems failing to recognize mirror bacteria.

Research led by Ricard Sole and his team at the Santa Fe Institute explored the implications of introducing a small population of mirror organisms into Earth’s biosphere. They employed computer models to analyze the constraints mirror life forms would encounter in diverse ecological scenarios.

According to Sole, for mirror life to pose a threat, it must first be capable of existing autonomously. The primary obstacle for mirror organisms is their exclusive ability to digest food comprised of molecules matching their chirality.

“Envisioning the engineering of dedicated ‘mirror food’ to nourish mirror organisms complicates rather than resolves the issue,” states Sole. “The development of a distinct ‘mirror biosphere’ would necessitate a continuous industrial system to produce vast quantities of mirror chiral biomolecules, including mirror sugars, mirror amino acids, and mirror lipids, alongside isolated nutrients.”

The research model emphasized whether mirror organisms could autonomously colonize actual ecological settings rather than survive temporarily in laboratory conditions equipped with artificial feeding systems.

“We believe that mirror life will encounter formidable barriers across a range of ecological conditions, presenting challenges to successful establishment,” Sole elaborates. “Nonetheless, critical unanswered questions remain that warrant further exploration, including long-term evolutionary dynamics and more realistic models detailing immune interactions with mirror organisms.”

This study is currently available on a preprint server pending peer review. A group of scientists focused on mirror life has issued a statement urging revisions of the paper.

Bone Cooper, a co-author of the statement from the University of Pittsburgh, noted to New Scientist that although mirror microorganisms initially grow more slowly than their native counterparts due to nutrient mismatches, they can thrive on numerous achiral nutrients. “Moreover, the mirror cell population may quickly adapt, essentially generating a second tree of life,” Cooper asserts.

The study suggests that Earth’s existing biodiversity could function as a “firewall” against mirror organisms, as natural life forms are optimized for their environments, thus outcompeting mirror forms. In the case of mirror bacteria, Sole and his colleagues contend that the immune system may still identify them as foreign invaders.

Yet, Cooper remains skeptical. “Numerous examples from invasion biology highlight the susceptibility of biodiverse ecosystems to invaders that lack natural predators,” he remarks.

Kate Adamala, one of the 2024 authors from the University of Minnesota, supports Solé’s hypothesis regarding the scarcity of food rich in identical chiral molecules as a critical limitation for mirror organisms. “This intrinsic disadvantage is a universal hurdle for mirror life forms in any natural ecosystem,” she notes.

However, she adds that these organisms might utilize photosynthesis for self-sustenance or leverage naturally occurring chiral molecules. “Although creating such an organism would be incredibly challenging, it’s not entirely implausible,” Adamala explains. “At the time, it wasn’t clear why the broader scientific community stood firmly against labeling this possibility as ‘very unlikely.’”

Solé affirms that his team has contemplated the potential for mirror organisms to exploit non-chiral nutrients or photosynthesis but maintains that they would still confront significant ecological hurdles.

“The crucial inquiry is not merely whether some nutrients are available, but whether there is enough access to facilitate sustainable growth while contending with the established biosphere,” he emphasizes. “Even if mirror organisms could subsist on a limited selection of achiral compounds, they would still face severe ecological constraints, including resource quality, dilution, competition, and the inability to efficiently metabolize the majority of naturally available chiral biomolecules.”

Philippa Lentzos, a Professor at King’s College London, posits that while mirror life is a legitimate future concern, it should not detract from pressing immediate biological risks. “The appropriate response is not to panic or dismiss these findings but to advocate for prudent governance, clear protocols regarding hazardous work, and a comprehensive research agenda that does not neglect pressing biosafety and biosecurity priorities,” she states.

“The evidence presented in this study regarding ecological constraints does not negate the necessity for governance; instead, it underscores the importance of an evidence-based adaptive approach. We must discern the assumptions influencing risks, identify the uncertainties, and ascertain which types of work will significantly alter the situation,” Lentzos concludes.