In this study we discuss the potential risks and ethical considerations of using synthetic biology technologies to create an alternate form of life called mirror bacteria. We call upon the broader scientific community and policymakers to engage in discussion and to pursue preventive measures to avert this a potentially existential threat from unfolding. 

All known life on Earth is homochiral, meaning DNA and RNA are composed of right-handed nucleotides, and proteins are made from left-handed amino acids. Mirror versions of these and other essential components of life can be made now using chemical synthesis. While these chemically synthesized mirror proteins and nucleic acids in themselves pose no threats, it may eventually become possible to make thousands of different mirror proteins and a complete million base pair mirror bacterial genome and assemble all of this to produce a living mirror bacterium. Such a bacterium might be engineered so that it could pose a risk to our biosphere. This is not certain, but a possibility.

Mirror bacteria would function just as their natural, homochiral counterparts with some exceptional differences. First, mirror bacteria would likely evade the immune defenses of humans, animals, plants in a way that could lead to death of the infected organism. This would be analogous to risks some humans with severely defective immune systems have that force them to live lives in isolation bubbles to avoid all possible infections. Similarly, mirror bacteria would be unaffected by naturally occurring bacteriophages, which are viruses that infect and are responsible for a large fraction of bacterial death in our oceans and other aqueous environments. Protozoans might be able to ingest mirror bacteria but not effectively metabolize their mirror proteins and carbohydrates. This could cause massive environmental changes. Our homochiral world is ill equipped to defend against mirror versions of life.

The path to mirror bacteria is not inevitable. First, mirror bacterial creation would likely require 10-30 years technology development before being possible and would require a very large investment. That investment at this point would only have a payoff of new knowledge because no one has a strong argument for utility of mirror bacteria. Any medical uses of mirror proteins and nucleic acids can be met by current chemical synthesis approaches. Also to reiterate, we are not sure if they would pose a grave threat to our world or not. Still, the group of scientists that wrote the “Confronting risks of mirror bacteria,” published in Science, believe this is a non-zero risk of terrible consequences if synthetic biologists were to make these organisms and that decisions about how to address this risk need further discussion.

The limited utility of mirror bacteria does not justify the significant risks involved. No biocontainment strategy would offset this risk. We recommend preventing the creation of mirror bacteria, advancing oversight of enabling technologies and raw materials, and encourage further research into the potential risks.

Related applications

Mirror biomolecules, such as mirror-image nucleic acids and proteins, have scientific and potential therapeutic applications. These include research applications like aptamers, biocatalysis, and phage display, as well as the incorporation of D-amino acids into synthetic peptide or protein drugs.

We recommend that research on mirror biomolecules should continue, as it does not directly enable the creation of mirror bacteria and is of great value to basic science.

Author statements

“JCVI has a long history of measured and deliberate review and discourse on ethical and societal issues surrounding new and exciting, but potentially problematic areas of genomic research. Before we began experiments in constructing the first synthetic bacterial cell, we engaged with bioethicists and other thought leaders about the work and its implications. We believe that mirror life is an area that has the potential to cause catastrophic issues for life on Earth. A halt on efforts aimed at its creation is warranted until we can better understand the risks. Engagement and discourse with the scientific community, governments and the public are imperative. There are some potential upsides of this work that offer positive outcomes in areas such as drug development, but without a cautious approach we risk grave outcomes. We hope that this paper will serve as the wake-up call for all of us to come together and develop a rational path forward.” – J. Craig Venter, Ph.D.

“The danger of mirror life is its fundamental difference. Mirror molecules bacteria might be unassailable by the non-mirror world as a consequence of their basic reversed molecular structure. A self-replicating organism built of from mirror components — one that’s capable of sustaining itself and multiplying in the wild — would likely be invisible to many of the processes nature has evolved that keep a species in check. It’s vital that we head off those risks before they materialize.” – John Glass, Ph.D.

Synthetic genomics policy research at J. Craig Venter Institute

The J. Craig Venter Institute (JCVI) takes biosafety, biosecurity, environmental protection, and ethical considerations of research seriously. In 2007, we published a report on the examination of safety, security concerns, and governance related to the emerging field of synthetic genomics. Additional JCVI co-authored reports have expanded on this initial effort, examining regulatory challenges, technological advancements, the environment, and the geopolitical landscape as it relates to biotechnology.

We have consistently applied these same standards to our own body of work. In 2010, when we announced the construction of the first self-replicating bacterial cell with a synthetic genome, we also laid out the ethical and societal implications of this seminal work as well as the scientific rationale. Furthering this research, in 2016, we announced the construction of the first self-replicating bacterial cell with a minimized synthetic genome. Again, we shared additional discussions around the ethical and societal implications of synthetic genomics research at JCVI.

As the science of synthetic biology advances, so too must the conversations around the ethical, societal, practical, technological, biosafety, and biosecurity impacts continue. JCVI is committed to our mission to understand more about the biological world, and to develop unique insights and answers about disease, health, and the environment for the benefit of all.

Funding

J. Craig Venter Institute and staff involved received no funding related to this research.

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