Plasmid-mediated dissemination of antibiotic resistance among fecal Enterobacteriaceae in natural ecosystems may contribute to the persistence of antibiotic resistance genes in anthropogenically impacted environments. Plasmid transfer frequencies measured under laboratory conditions might lead to overestimation of plasmid transfer potential in natural ecosystems. This study assessed differences in the conjugative transfer of an IncP-1 (pKJK5) plasmid to three natural Escherichia coli strains carrying extended-spectrum beta-lactamases, by filter mating. Matings were performed under optimal laboratory conditions (rich LB medium and 37°C) and environmentally relevant temperatures (25, 15 and 9°C) or nutrient regimes mimicking environmental conditions and limitations (synthetic wastewater and soil extract). Under optimal nutrient conditions and temperature, two recipients yielded high transfer frequencies (5 × 10–1) while the conjugation frequency of the third strain was 1000-fold lower. Decreasing mating temperatures to psychrophilic ranges led to lower transfer frequencies, albeit all three strains conjugated under all the tested temperatures. Low nutritive media caused significant decreases in transconjugants (−3 logs for synthetic wastewater; −6 logs for soil extract), where only one of the strains was able to produce detectable transconjugants. Collectively, this study highlights that despite less-than-optimal conditions, fecal organisms may transfer plasmids in the environment, but the transfer of pKJK5 between microorganisms is limited mainly by low nutrient conditions.
MULTIFILE
Urban flooding and thermal stress have become key issues formany cities around the world. With the continuing effects of climatechange, these two issues will become more acute and will add to theserious problems already experienced in dense urban areas. Therefore, thesectors of public health and disaster management are in the need of toolsthat can assess the vulnerability to floods and thermal stress. The presentpaper deals with the combination of innovative tools to address thischallenge. Three cities in different climatic regions with various urbancontexts have been selected as the pilot areas to demonstrate these tools.These cities are Tainan (Taiwan), Ayutthaya (Thailand) and Groningen(Netherlands). For these cities, flood maps and heat stress maps weredeveloped and used for the comparison analysis. The flood maps producedindicate vulnerable low-lying areas, whereas thermal stress maps indicateopen, unshaded areas where high Physiological Equivalent Temperature(PET) values (thermal comfort) can be expected. The work to dateindicates the potential of combining two different kinds of maps to identifyand analyse the problem areas. These maps could be further improved andused by urban planners and other stakeholders to assess the resilience andwell-being of cities. The work presented shows that the combined analysisof such maps also has a strong potential to be used for the analysis of otherchallenges in urban dense areas such as air and water pollution, immobilityand noise disturbance.
Urban flooding and thermal stress have become key issues for many cities around the world. With the continuing effects of climate change, these two issues will become more acute and will add to the serious problems already experienced in dense urban areas. Therefore, the sectors of public health and disaster management are in the need of tools that can assess the vulnerability to floods and thermal stress. The present paper deals with the combination of innovative tools to address this challenge. Three cities in different climatic regions with various urban contexts have been selected as the pilot areas to demonstrate these tools. These cities are Tainan (Taiwan), Ayutthaya (Thailand) and Groningen (Netherlands). For these cities, flood maps and heat stress maps were developed and used for the comparison analysis. The flood maps produced indicate vulnerable low-lying areas, whereas thermal stress maps indicate open, unshaded areas where high Physiological Equivalent Temperature (PET) values (thermal comfort) can be expected. The work to date indicates the potential of combining two different kinds of maps to identify and analyse the problem areas. These maps could be further improved and used by urban planners and other stakeholders to assess the resilience and well-being of cities. The work presented shows that the combined analysis of such maps also has a strong potential to be used for the analysis of other challenges in urban dense areas such as air and water pollution, immobility and noise disturbance.
