"Mirror bacteria" being made in labs could be a looming risk to the health of humanity, scientists have warned.
These hypothetical organisms get their name from how their molecules would face the opposite way to those in the cells of all existing life—akin to the mirrored shapes of our left and right hands—and, because of this fundamental strangeness, could be dangerous to humans, animals and plants alike.
The synthetic bacteria are currently in the early stages of development, and may come to fruition in over a decade, according to a paper in the journal Science.
"Our view is that mirror bacteria and other mirror organisms should not be created," the researchers wrote.
The direction of a molecule, such as the proteins in our body, is known as its chirality. All DNA and RNA found in all Earth life forms are made from "right-handed" molecules, while proteins are made from nearly entirely "left-handed" amino acids.
The chirality of a molecule can determine its structure and function. For example, the drug thalidomide exists as two different chiralities—known formally as enantiomers—where one is therapeutic for the treatment of morning sickness, and the other causes severe birth defects.
According to the new paper, work has begun on building bacteria with mirrored molecules of the opposite chirality to all other life on Earth, with left-handed DNA and right-handed proteins.
"Driven by curiosity and plausible applications, some researchers had begun work toward creating lifeforms composed entirely of mirror-image biological molecules," the researchers wrote. "The capability to create mirror life is likely at least a decade away and would require large investments and major technical advances."
According to the new paper, researchers fear that mirror bacteria could be able to evade natural predators like phage viruses and microscopic protists, or even immune cells in our bodies, as they rely on chiral-dependent binding to recognize bacteria.
This could mean that immune defenses may not be as effective against mirror bacteria, leaving animals and plants vulnerable to unhindered infection.
"Our analysis suggests that mirror bacteria would likely 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 researchers wrote.
The scientists suggest that, in a worst-case situation, mirror bacteria could rapidly and lethally infect many of the lifeforms on our planet.
"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. Even a mirror bacterium with a narrower host range and the ability to invade only a limited set of ecosystems could still cause unprecedented and irreversible harm," the researchers wrote.
The researchers note that while this threat is still a long way out, it may very well occur within the next few decades. They say that in the coming years before mirror bacteria are developed, we need to create limitations regarding research into these organisms, if not banning it entirely.
"Unless compelling evidence emerges that mirror life would not pose extraordinary dangers, we believe that mirror bacteria and other mirror organisms, even those with engineered biocontainment measures, should not be created," the researchers wrote.
"We therefore recommend that research with the goal of creating mirror bacteria not be permitted, and that funders make clear that they will not support such work."
If this research cannot be stopped, the scientists suggest developing ways to control and prevent these mirror bacteria from causing any harm.
"Such research might include studying the interaction of mirror biomolecules with the immune system as well as developing detection methods and biosurveillance systems. Although countermeasures could not prevent widespread harm, they might offer some limited or localized protection," they said.
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References
Adamala, K. P., Agashe, D., Belkaid, Y., De C Bittencourt, D. M., Cai, Y., Chang, M. W., Chen, I. A., Church, G. M., Cooper, V. S., Davis, M. M., Devaraj, N. K., Endy, D., Esvelt, K. M., Glass, J. I., Hand, T. W., Inglesby, T. V., Isaacs, F. J., James, W. G., Jones, J. D. G., . . . Zuber, M. T. (2024). Confronting risks of mirror life. Science. https://doi.org/10.1126/science.ads9158
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