Scientists have discovered a 5,000-year-old bacterium in a Romanian ice cave that resists several contemporary antibiotics. The microbe, isolated from permafrost, carries over 100 resistance genes and could inhibit dangerous superbugs. This finding highlights natural evolution of resistance and potential biotechnological applications.
In the Scarisoara Ice Cave in Romania, researchers extracted a bacterial strain named Psychrobacter SC65A.3 from a 5,000-year-old ice layer. The team drilled a 25-meter ice core from the cave's Great Hall, which preserves a record spanning 13,000 years. To avoid contamination, samples were sealed in sterile bags and kept frozen during transport to the laboratory. There, scientists sequenced the genome and tested the bacterium against 28 antibiotics from 10 classes.
The analysis revealed resistance to 10 antibiotics, including rifampicin, vancomycin, ciprofloxacin, trimethoprim, clindamycin, and metronidazole. These drugs treat conditions such as tuberculosis, colitis, urinary tract infections, lung infections, skin infections, bloodstream infections, and reproductive system infections. "The Psychrobacter SC65A.3 bacterial strain isolated from Scarisoara Ice Cave, despite its ancient origin, shows resistance to multiple modern antibiotics and carries over 100 resistance-related genes," said Dr. Cristina Purcarea, a senior scientist at the Institute of Biology Bucharest of the Romanian Academy. "But it can also inhibit the growth of several major antibiotic-resistant 'superbugs' and showed important enzymatic activities with important biotechnological potential."
Psychrobacter SC65A.3 belongs to cold-adapted bacteria, some of which cause infections but also hold promise for biotechnology. The strain's genome includes nearly 600 genes of unknown function and 11 genes that may combat bacteria, fungi, and viruses. "Studying microbes such as Psychrobacter SC65A.3 retrieved from millennia-old cave ice deposits reveals how antibiotic resistance evolved naturally in the environment, long before modern antibiotics were ever used," Purcarea explained.
The discovery raises concerns about melting ice potentially releasing resistance genes to modern bacteria, exacerbating global antibiotic resistance challenges. However, it also offers opportunities, as the bacterium produces unique enzymes and antimicrobial compounds that could lead to new antibiotics and industrial innovations. The research was published in Frontiers in Microbiology in 2026.
