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Roman Baths-a potential source of antimicrobial compounds?
In a recent study published in The Microbe, researchers analyzed the elemental composition and microbial diversity of the Roman Baths, with a focus on prokaryotes. They found a high diversity of bacteria and archaea with potential antimicrobial properties. This means that the Roman Baths could indeed have other kinds of healing properties, thanks to microbes.
The rise in antimicrobial resistance (AMR) amongst known pathogenic bacteria is a major cause for concern around the world. This makes it important to find novel antimicrobial compounds that could combat infections effectively. At present, soil and marine environments have been widely explored to identify antimicrobial compounds. Exploring other environments such as hot springs may hold the key to discovering novel antimicrobial compounds and the Roman Baths could be yet another promising source for this discovery.
Recent Findings
To identify the elemental composition and diversity of the microbes, the researchers collected the water, biofilm and sediment samples from both the pools. They recorded the temperature, pH, salinity and dissolved oxygen levels of the water samples. The samples were then analyzed in the lab for the elements and microbes present in them. The researchers found that both the pools of water differed in their elemental composition. The samples from the King’s Spring had a higher temperature, and a higher pH. Further, they were enriched in sulfur, magnesium, potassium, calcium, phosphorus, manganese and iron compared to Great Bath.
They next used 16S rRNA sequencing to analyze the bacterial and archaeal diversity of both the locations. The water samples showed a marked difference in the abundance of the prokaryotes between the two locations. The Archaea Crenarchaeota was the most abundant phylum in the warmer King’s Spring, however it was absent in Great Bath. Crenarchaeota are a kind of archaea that were initially identified in hot springs. Most of them are thermophilic and use sulfur as a source of energy. While Cyanobacteria, a kind of photosynthetic bacteria, was the most abundant phylum in Great Bath, and possibly the reason for its green colored waters.
Many other phyla were present in both the samples, including some unidentified bacteria. The researchers further analyzed the microbial diversity of the biofilm and sediment samples of both the pools. Archaea were present in the biofilm and sediment samples of Great Bath, however bacteria dominated these samples. There was not much of a clear difference in the biofilm and sediment samples between the two pools as compared to the water samples. Members of the Actinobacteria and Myxococcota phyla were present in all samples. These phyla are promising candidates to isolate novel antimicrobial compounds. Actinobacteria are the source of many known antibiotics, such as, erythromycin, kanamycin, streptomycin, tetracycline, and vancomycin. Myxococcota are also known to be a source for antimicrobial compounds.
To isolate Actinobacteria that had the potential to produce antimicrobial compounds, the researchers spread the water, sediment and biofilm samples from the Roman Baths onto specific growth media. The isolates were then exposed to antimicrobial resistant strains of E. coli and S. aureus, which are known pathogens. The isolates that were able to inhibit the growth of these pathogenic bacteria, were further screened against other known antimicrobial resistant bacteria. Many of the isolates were able to inhibit the growth of otherwise resistant and difficult to treat microbes. However, most of these isolates were from the Pseudomonas genus, while a handful of Actinobacteria were isolated. These isolates showed very little activity against pathogenic bacteria, possibly because the isolates were cultured under non-native conditions.
The researchers hope to culture Actinobacteria using the water of the Roman Baths to provide native growth conditions. Other follow up studies would include isolating Myxococcota, identifying the organisms that produce antimicrobial compounds and eventually isolating these organisms. They further hope to determine the novelty of the antimicrobial compounds (being produced by the organisms identified from the Roman Baths), determine whether these can be brought into human use and identify their mode of action. By uncovering the microbial diversity of the Roman Baths and identifying it as a source of antimicrobials, Fina and colleagues open the doors for antimicrobial discovery from other hot springs around the world.
The next time you visit a hot spring, just remember that you might be walking into a treasure trove of antimicrobials and the source of a novel antimicrobial.
Link to the original post: Fina E, Kiernan M, Whatmough B, et al. Physicochemical and metagenomic analysis of samples from the Roman Baths (Bath, UK) reveals high bacterial and archaeal diversity and a potential for antimicrobial discovery. The Microbe. 2024;3:100075.
Featured image: An image of the Roman Baths, Bath, UK. Image source: Roman Bath House – http://www.joyofmuseums.com – Roman Baths (Bath), 14 January 2018. https://commons.wikimedia.org/wiki/File:Roman_Bath_House_-_www.joyofmuseums.com_-_Roman_Baths_%28Bath%29.jpg.
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