Scientists have discovered a 5,000-year-old bacterial strain preserved in the ice of Romania’s Scarisoara Ice Cave that exhibits resistance to ten modern antibiotics. The finding, published in Frontiers in Microbiology, underscores how antibiotic resistance isn’t just a modern problem created by overuse of drugs, but an ancient phenomenon shaped by natural selection.
A Relic of the Past
The isolated strain, Psychrobacter cryohalolentis SC65A.3, was extracted from a 25-meter ice core. Psychrobacter species are naturally adapted to cold, saline environments and have a widespread global distribution. Despite its age, SC65A.3 is not only antibiotic-resistant but also possesses unique enzymatic properties. Researchers found it carries over 100 genes associated with drug resistance, including those effective against antibiotics used to treat tuberculosis and severe urinary tract infections.
Why This Matters
The discovery is significant for two key reasons. First, it provides evidence that antibiotic resistance existed in bacteria long before humans began using antibiotics. This suggests that resistance mechanisms evolved naturally in response to environmental pressures. Second, the strain’s genetic makeup could hold the key to both accelerating antibiotic resistance and creating new treatments.
The Dual Nature of Ancient Resistance
The ancient bacteria presents a paradox: it contains genes that could worsen the global antibiotic crisis if released into modern ecosystems through melting ice, but also produces enzymes and compounds with potential biotechnological value. These compounds could inspire the development of novel antibiotics, industrial enzymes, and other innovations.
“Studying microbes such as Psychrobacter SC65A.3 reveals how antibiotic resistance evolved naturally in the environment, long before modern antibiotics were ever used,” said Dr. Cristina Purcarea of the Romanian Academy.
The study sequenced the genome of SC65A.3 to identify genes linked to survival in extreme cold and antimicrobial resistance. Testing confirmed resistance to a broad range of antibiotics commonly used in clinical practice. The researchers also found that the strain can inhibit growth in several existing antibiotic-resistant “superbugs.”
A Reservoir of Resistance?
The findings suggest that cold environments may serve as natural reservoirs for resistance genes, raising concerns about the potential for ancient microbes to contribute to modern antibiotic resistance. As climate change accelerates ice melt, these genes could spread to contemporary bacteria, exacerbating an already critical public health threat.
However, this is not just a warning: SC65A.3 also represents a unique source of untapped biochemical potential. The strain’s enzymes and antimicrobial compounds may hold the key to developing the next generation of antibiotics and biotechnological solutions.
The discovery underscores the complex interplay between ancient microbial life and modern medicine. The fate of antibiotic resistance, and potentially the future of antibacterial therapies, may lie buried within millennia-old ice.
