(1) Background: Airborne microbes are an integral part of a cave ecosystem. Cave allochtonous airborne microbiota, which occurs mainly during aerosolization from an underground river, from animals, and from visitors, is particularly pronounced in show caves. The impacts of tourists and natural river aerosolization on the cave air were estimated in large cave spaces within the Škocjan Caves; (2) Methods: Simultaneously with the measurements of atmospheric parameters, cultivable airborne bacteria were impacted, counted and identified using MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry); (3) Results: A mix of bacteria typically associated with humans and with natural habitats, including a large percentage of non-identified isolates, was found in the cave air. Few of the isolates were attributed to Risk Group 2. A strong positive correlation between tourist numbers and the rise in the concentration of airborne bacteria was indicated. Concentration of airborne bacteria rises to particularly high levels close to the underground river during periods of high discharge. A 10-times lower discharge reflected an approximately 20-times lower concentration of airborne bacteria; (4) Conclusions: Caves that are open and visited contain a diverse airborne microbiota originating from different sources. Enormous cave chambers that display relatively dynamic cave climate conditions do not normally support the enhancement of airborne bacterial concentrations.
The Škocjan Caves are included in UNESCO's World Heritage List due to their outstanding natural features. The caves include a large underground canyon containing the Reka River, collapse dolines with vegetation in rock fissures and impressive archaeological sites with a rich history of speleological and scientific research. They are also included in the Ramsar Directory of Wetlands of International Importance. Together with their broader surface area, the site is known as the UNESCO Karst Biosphere Reserve. The aim of the management of the reserve is to protect the World Heritage Site and to preserve its outstanding universal value for future generations. The protection activities are regulated by the provisions of international documents, the Škocjan Caves Regional Park Act and the park's management plan. These activities include monitoring of the water quality in the Reka River and meteorological surveys on the surface. Monitoring of the microclimate of the caves focuses on measuring the effects of tourism and monitoring the levels of radon, with the aim of the ensuring the safety of the park's employees. Ensuring a favourable status for the underground habitats and species is laid down in the Natura 2000 management programme. Particular attention is paid to ensuring high-quality, safe visits to the caves and providing educational and awareness-raising activities on the surface of the park.
Escherichia coli, one of the primary intestinal commensal bacteria in humans and endothermic animals, is commonly considered an indicator of faecal pollution. E. coli strains were isolated from karst rivers under different hydrological conditions, from footpaths in tourist caves and from bat guano. Isolates were tested for phenotypic resistance to ampicillin, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline and trimethoprim. The highest percentage of antimicrobial resistant E. coli was found in karst waters, followed by those from surface swabs and from bat guano. Several isolates from rivers and swabs exhibited multidrug-resistant phenotype. Environmental conditions impact the populations of E. coli; a positive correlation between dissolved oxygen and E. coli counts, and a negative correlation between conductivity and E. coli concentrations have been observed for karst rivers. Malenščica (Slovenia), a drinking water resource with an extensive catchment area, contained a relative high percentage of antimicrobial-resistant E. coli strains. None of the isolates from bat guano was resistant to ampicillin, chloramphenicol, and tetracycline. Future monitoring of bats should consider a regular follow-up of indicative microbial disease indicators in fresh guano. Regular cleansing of tourist footpaths in caves and disinfection barriers at the cave entrances reduce the concentration and transmission of E. coli significantly. A future, more detailed, study on characterization of additional E. coli isolates is needed to reveal their pathogeneicity, mechanisms of antibiotic resistance, mobile genetic elements, and gene transfer frequencies to other members of the karst microbiome.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.