Distribution and quantification of antibiotic resistance genes in a large subalpine lake (Lugano Lake) and tributary rivers.

OBJECTIVES: Antibiotic resistance genes (ARGs) are causing increasing problems, especially in clinical settings. Nowadays, they are considered important environmental contaminants, but little is known about their fate in the environment or how they affect natural microbial populations. In the environment, especially in water affected by anthropic activities such as discharge of hospital, urban, and industrial wastewater treatment plant (WWTP) and agricultural runoff, antibiotic determinants may become part of the environmental gene pool, spread horizontally, and be ingested by humans and animals via contaminated food and drinking water. The aim of this work was to monitor long-term the presence of antibiotic resistance determinants in water samples collected from a subalpine lake and some tributary rivers located in the southern part of Switzerland, and to assess if anthropic activities could influence the distribution of antibiotic resistance genes present in water environments. METHODS: We analysed water samples by qPCR to quantify five antibiotic resistance genes that confer resistance to the major classes of antibiotics used in clinical and veterinary settings (ß-lactams, macrolides, tetracycline, quinolones, and sulphonamides). Water samples were collected from January 2016 to December 2021, from three rivers located in south Switzerland and from five different sites of Lugano Lake. RESULTS: The most abundant genes were sulII, followed by ermB, qnrS, and tetA; they were found especially in the river influenced by wastewater treatment plants and in the lake near the potable water uptake plant. We observed an overall decrease in the number of resistance genes during the three years. CONCLUSIONS: Our results indicate that the aquatic ecosystems monitored in this study are a reservoir of ARGs and could potentially be a setting for the transmission of resistance from the environment to humans.

Fungal communities on alpine cheese rinds in Southern Switzerland.

BACKGROUND: The biodiversity of the mycobiota of soft cheese rinds such as Brie or Camembert has been extensively studied, but scant information is available on the fungi colonizing the rinds of cheese produced in the Southern Switzerland Alps. This study aimed at exploring the fungal communities present on rinds of cheese matured in five cellars in Southern Switzerland and to evaluate their composition with regards to temperature, relative humidity, type of cheese, as well as microenvironmental and geographic factors. We used macro- and microscopical morphology, matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, and sequencing to characterize the fungal communities of the cheeses, and compared them with metabarcoding targeting the ITS region. RESULTS: Isolation by serial dilution yielded 201 isolates (39 yeasts and 162 filamentous fungi) belonging to 9 fungal species. Mucor and Penicillium were dominant, with Mucor racemosus, M. lanceolatus, P. biforme, and P. chrysogenum/rubens being the most frequent species. All but two yeast isolates were identified as Debaryomyces hansenii. Metabarcoding detected 80 fungal species. Culture work and metabarcoding produced comparable results in terms of similarity of the fungal cheese rind communities in the five cellars. CONCLUSIONS: Our study has shown that the mycobiota on the rinds of the cheeses studied is a comparatively species-poor community influenced by temperature, relative humidity, type of cheese, and manufacturing steps, as well as microenvironmental and possibly geographic factors.