Jörg Villiger's research while affiliated with University of Zurich and other places

Publications (6)

Article
Full-text available
The beta lactamase gene blaCTX-M, responsible of the resistance to cephalosporins, has been detected in microbes from hospitals to open waters. We studied the seasonality and stability of blaCTX-M in Lake Maggiore over 3 years and the role of potential inputs of allochthonous bacteria and/or antibiotic pollution in promoting its occurrence. blaCTX-...
Article
Gravity-driven membrane (GDM) filtration is a promising tool for low-cost decentralized drinking water production. The biofilms in GDM systems are able of removing harmful chemical components, particularly toxic cyanobacterial metabolites such as microcystins (MCs). This is relevant for the application of GDM filtration because anthropogenic nutrie...
Article
Full-text available
The most prominent responses of Lake Zurich to climate warming include the increase of surface water temperatures, a reduced depth of spring mixing, and the persistent thriving of the harmful cyanobacterium Planktothrix rubescens, a low-light adapted species concentrating in the metalimnion during summer. To study changes of its habitat, we assesse...
Article
Full-text available
Gravity-driven membrane (GDM) ultrafiltration systems require little maintenance: they operate without electricity at ultra-low pressure in dead-end mode and without control of the biofilm formation. These systems are already in use for water purification in some regions of the world where adequate treatment and distribution of drinking water is no...
Article
Bacterial diversity, community assembly, and the composition of the dissolved organic matter (DOM) were studied in three temporary subsurface karst pools with different flooding regimes. We tested the hypothesis that microorganisms introduced to the pools during floods faced environmental filtering towards a ‘typical’ karst water community, and we...
Article
Full-text available
Emerging interactions are key determinants of system productivity and efficiency in plant and animal communities, whereas their importance for planktonic microbial assemblages is unknown. We studied the relationship between two aquatic bacterial strains and a protistan predator with respect to cooperation and system efficiency. While competitive ex...

Citations

... In this context, antibiotic contamination of freshwater bodies can be considered as a disturbance factor of anthropogenic origin for bacterial communities (Fick et al., 2009), with strong potential effect on the selection, stabilization, and proliferation of potentially threatening resistances in aquatic environments heavily used by humans. In experimental freshwater communities the addition of antibiotics usually decreases bacterial abundance Eckert et al., 2019a;Eckert et al., 2019b) but its effect on diversity depends on the class of antibiotic (Liu et al., 2012) since different antibiotics target different bacterial taxa. Consequently, the addition of certain antibiotics, e.g. ...
... Previous studies indicated that during algal bloom period, the gravity-driven membrane (GDM) system was able to remove toxic cyanobacterial metabolites (microcystins). However, a much lower flux was obtained due to the algae attachment on the surface that reduced the membrane flux (Kohler et al. 2014;Silva et al. 2018). ...
... In contrast, constantly elevated biomass of P. rubescens is attributed to changes in the patterns of stratification and mixing due to climate change. During the last decades, years with incomplete mixing have become more frequent, for example, in Lake Zürich, allowing P. rubescens to increase its population as more cells survive as inoculum for the next season's population while holomixis would diminish cell density more strongly due to higher hydrostatic pressure in deep water layers [39,144]. On the other hand, reduced mixing can also result in nutrient depletion of the epilimnion through sedimentation and thus lead to lower abundance of P. rubescens, as observed in Lake Garda [40]. ...
... Previous studies indicated that during algal bloom period, the gravity-driven membrane (GDM) system was able to remove toxic cyanobacterial metabolites (microcystins). However, a much lower flux was obtained due to the algae attachment on the surface that reduced the membrane flux (Kohler et al. 2014;Silva et al. 2018). ...
... No measures are routinely taken to monitor ecological parameters, including the abundance, biomass, activity, and diversity of microbial communities (Griebler et al. 2010, Korbel & Hose 2011. As a consequence, our knowledge about the microbiology of karst aquifers and springs is rather limited (Farnleitner et al. 2005, Pronk et al. 2009, Wilhartitz et al. 2009, Shabarova et al. 2014, including the Slovenian karst. ...
... The bacterial abundance and the morphological distribution in water were measured by flow cytometry (BD Accuri C6) on single sample aliquots of 1.5 ml stained with SYBR Green I (final concentration 1%, Life Technologies). Counts were set to a minimum of 2 x10 6 events within the gates designed for single and doubling cells, and 5 x10 2 events in the gates for small and large aggregates, the first composed by 3-9 cells and the second by at least 10 cells [30]. Flow cytometry counts and morphologies were confirmed by further epifluorescence microscopy (Axioplan, Zeiss) analysis (DAPI stained samples collected on 0.22 µm black polycarbonate filters, Millipore). ...