A group of 38 researchers from nine countries — which includes experts in immunology, plant pathology, ecology, evolutionary biology, biosecurity and planetary sciences — published a paper on Science on potential risks from the development of mirror bacteria (synthetic organisms in which all molecules have reversed chirality, i.e. are ‘mirrored’) on Thursday (12/12). The researcher Daniela Bittencourt, from Embrapa Genetic Resources and Biotechnology (Brasília, DF), is one of the coauthors of the study and the only participating Latin-American scientist. Scientists had been working toward creating mirror bacteria, and while the capability is at least a decade away, recent years have seen significant progress. The newly published paper finds that, if created, these organisms may pose significant dangers to human, animal, plant, and environmental health. The authors underscore the need for broad dialogue to chart a path towards better understanding and mitigation of potential risks from mirror bacteria. The publication in Science is accompanied by a detailed 300-page technical report. While there is no is no imminent threat, the Science paper finds that such mirror organisms may pose serious risks as immune defenses in humans, animals, and plants rely on recognizing specific molecular shapes found in invading bacteria. If these shapes were reflected — as they would be in mirror bacteria —, recognition would be impaired and many basic immune defenses could fail, potentially leaving organisms vulnerable to infection. The analysis also suggests that mirror bacteria in the environment may be able to evade natural predators that would kill the bacteria and limit their populations. Moreover, transport via animals and humans could enable spread between diverse ecosystems. Persistent and widespread environmental populations of mirror bacteria would expose humans, animals and plants to an ongoing risk of infection — a serious threat to humans and to global ecosystems. The authors call for further scrutiny of their findings and conclude that, unless compelling evidence emerges that these organisms would not pose extraordinary dangers, mirror bacteria should not be created. This paper marks a starting point for a broader discussion about the risks from mirror bacteria, including participation from the global scientific community, policymakers, research funders, and other stakeholders. Several of the authors on the paper are involved in planning a series of events throughout 2025, including events planned at the Institut Pasteur in France, the University of Manchester in the U.K. and the National University of Singapore, to scrutinize the findings of the paper and discuss steps that can be taken to prevent risks from mirror bacteria. Ethics For researcher Daniela Bittencourt, the scientific community has the responsibility to advance ethically and with a rigorous approach to biosecurity, ensuring that the benefits of biotechnological innovations are not overshadowed by potential risks to public health and the environment. “From a theoretical standpoint, mirror bacteria offer valuable opportunities to deepen our understanding of the fundamental biology of organisms, allowing us to explore how the inversion of molecular orientations can impact cellular functioning,” Daniela explains. According to her, the bacteria whose molecules are mirrored, that is, with structures that are inverted from their natural shapes, could have significant practical applications, such as the development of new materials that are more resistant to degradation, and the creation of new drugs that are more efficient and more resistant to natural biological processes. However, the authors argue that the possibilities offered by mirror molecules can be achieved without the need to make mirror bacteria. “Despite such possibilities, mirror bacteria pose significant risks, as highlighted in the paper. Concerns about those risks are even more relevant given the recent advances in synthetic biology methodologies, which have made the creation of such organisms more feasible. Therefore, it is crucial that there is close collaboration between scientists, policymakers and regulators to ensure the responsible advance of biotechnology, balancing innovation with due caution”, the researcher asserts. * Based on press release by Milltown Partners.