The world-famous Roman Baths are home to a diverse range of microorganisms which could be critical in the global fight against antimicrobial resistance, a new study suggests. The investigation of extreme ecological niches, such as hot springs, has gained recent interest due to their unique ecosystems, increasing the chance for novel antimicrobial natural product discovery. The study, published in the journal The Microbe, is the first to provide a detailed examination of the bacterial and archaeal communities found within the waters of the popular tourist attraction in the city of Bath (U.K.).

Scientists collected samples of water, sediment and biofilm from locations within the Roman Baths complex including the King’s Spring (where the waters reach around 45 degree C) and the Great Bath, where the temperatures are closer to 30 degree C. The samples were then analysed using cutting edge sequencing technology and traditional culturing techniques were employed to isolate bacteria with antibiotic activity.

Around 300 distinct types of bacteria were isolated across the Roman Baths site — among them the key candidate groups, Actinobacteria and Myxococcota, known for antibiotic production — with different examples being more prominent within the varying water temperatures. Further tests showed 15 of these isolates — including examples of Proteobacteria and Firmicutes — showed varying levels of inhibition against human pathogens including E.coli, Staphylococcus Aureus and Shigella flexneri.

“From initial isolation experiments, 297 isolates were purified, of which 15 showed broad spectrum activity against human pathogens, though interestingly these were not from target genera in the Actinobacteria. From these data, there is clear potential for novel antimicrobial natural products discovery from the Roman Baths, as has been demonstrated from other thermal hot springs globally,” the authors write.

The research comes at a time when the need for new sources of antibiotics is at unprecedented levels, with resistance of bacteria to currently used medication estimated to be responsible for more than 1.25 million deaths globally each year. The researchers say a significant amount of additional investigation is required before the microorganisms found in the Roman Baths can be applied in the fight against disease and infection globally. However, they add that this initial study has shown there is clear potential for novel antimicrobial natural products contained within its hot springs to be explored further for that purpose.