(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.

We studied the efficiency of three culture series of the microalgae Phaeodactylum tricornutum (P. tricornutum) and bacteria Thalassospira sp. (axenic microalgae, bacterial culture and co-culture of the two) in removing bisphenols (BPs) from their growth medium. Bacteria were identified by 16S ribosomal RNA polymerase chain reaction (16S rRNA PCR). The microorganism growth rate was determined by flow cytometry. Cultures and isolates of their small cellular particles (SCPs) were imaged by scanning electron microscopy (SEM) and cryogenic transmission electron microscopy (Cryo-TEM). BPs were analyzed by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). Our results indicate that some organisms may have the ability to remove a specific pollutant with high efficiency. P. tricornutum in axenic culture and in mixed culture removed almost all (more than 99%) of BPC2. Notable differences in the removal of 8 out of 18 BPs between the axenic, mixed and bacterial cultures were found. The overall removals of BPs in axenic P. tricornutum, mixed and bacterial cultures were 11%, 18% and 10%, respectively. Finding the respective organisms and creating microbe societies seems to be key for the improvement of wastewater treatment. As a possible mediating factor, numerous small cellular particles from all three cultures were detected by electron microscopy. Further research on the mechanisms of interspecies communication is needed to advance the understanding of microbial communities at the nano-level.

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.

Around 85% of the environments on Earth are permanently or seasonally colder than 5 °C. Among those, the poles constitute unique biomes, which harbor a broad variety of microbial life, including an abundance of fungi. Many fungi have an outstanding ability to withstand extreme conditions and play vital ecosystem roles of decomposers as well as obligate or facultative symbionts of many other organisms. Due to their dispersal capabilities, microorganisms from cryosphere samples can be distributed around the world. Such dispersal involves both species with undefined pathogenicity and potentially pathogenic strains. Here we describe the isolation of fungal species from pristine Arctic locations in Greenland and Svalbard and the testing of the expression of characteristics usually associated with pathogenic species, such as growth at 37 °C, hemolytic ability, and susceptibility to antifungal agents. A total of 320 fungal isolates were obtained, and 24 of the most abundant and representative species were further analyzed. Species known as emerging pathogens, like Aureobasidium melanogenum, Naganishia albida, and Rhodotorula mucilaginosa, were able to grow at 37 °C, showed beta-hemolytic activity, and were intrinsically resistant to commonly used antifungals such as azoles and echinocandins. Antifungal resistance screening revealed a low susceptibility to voriconazole in N. albida and Penicillium spp. and to fluconazole in Glaciozyma watsonii and Glaciozyma-related taxon.