In the present study, biomass development and changes in community composition of phototrophic biofilms grown under different controlled ambient conditions (light, temperature and flow) were examined. Source communities were taken from a wastewater treatment plant and used to inoculate growth surfaces in a semi-continuous-flow microcosm. We recorded biofilm growth curves in cultures over a period of 30 days across 12 experiments. Biovolume of phototrophs and community composition for taxonomic shifts were also obtained using light and electron microscopy. Species richness in the cultured biofilms was greatly reduced with respect to the natural samples, and diversity decreased even further during biofilm development. Diadesmis confervacea, Phormidium spp., Scenedesmus spp. and Synechocystis spp. were identified as key taxa in the microcosm. While a significant positive effect of irradiance on biofilm growth could be identified, impacts of temperature and flow rate on biofilm development and diversity were less evident. We discuss the hypothesis that biofilm development could have been subject to multistability, i.e. the existence of several possible stable biofilm configurations for the same set of environmental parameters; small variations in the species composition might have been sufficient to switch between these different configurations and thus have contributed to overwriting the original effects of temperature and flow velocity.
Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Copy DOI
Abstract A key step toward developing appropriate evidence-based public health nutrition policies is determining exactly how that evidence should be collected and assessed. Despite this the extent to which different evidence bases influence policy selection is rarely explored. This article presents an epistemological framework which offers a range of considerations affecting this process generally and with particular implications for both micronutrient requirements and the role of behavior in the policy-making process. Qualitative case study data covering 6 European countries/regions (Czech Republic, Italy, the Netherlands, Nordic countries, Poland, and Spain), and three micronutrients (folate, iodine, and vitamin D), have been presented to illustrate the relevance of the Framework. Keywords: Public healthevidence basedpolicy makingnutritionEURRECA ACKNOWLEDGMENTS This work has been carried out within the EURRECA Network of Excellence (http://www.eurreca.org), financially supported by the Commission of the European Communities, Specific Research Technology and Development (RTD) Programme Quality of Life and Management of Living Resources within the 6th framework programme, contract no. 036196. This does not necessarily reflect the Commission's views or its future policy in this area. The contributions of authors were as follows: L. Timotijevic, J. Barnett, K.A. Brown, L. Lähteenmäki, and M.M. Raats were responsible for the study concept. L. Timotijevic, K.A. Brown, L.D. Wit, A.M. Sonne, J. Ruprich, I. Řehůřková, M. Jeruszka-Bielak, E. Sicinska, N.B. García, and A. Guzzon carried out data collection and basic data analysis. L. Timotijevic completed analysis and prepared the draft of the final article. Editing was carried out by L. Timotijevic, K.A. Brown, L. Lähteenmäki, M.M. Raats, J. Barnett, and R. Sheperd. We would also like to acknowledge the contributions made to this body of work by Wojciech Roszkowski and DR Matthew Peacock. The preparation of this article was coordinated by Mandy Claessens from ILSI Europe and the copy editing by EUFIC.
Photosynthetic performance of algal-bacterial biofilms from an Italian wastewater treatment plant was studied in a flow-lane photobioreactor at different irradiances, temperatures, and flow regime to evaluate the effects of these environmental parameters on biofilms' functioning, in view of application of these communities in wastewater biological treatment. Pulse amplitude modulated fluorescence was used to estimate the effective quantum yield of PSII (ΔF/Fm') of the light-acclimated biofilms and to perform rapid light curves (RLCs) for the determination of the photosynthetic parameters (rel.ETRmax, α, Ik). Chl a, ash free dry weight (AFDW), and dry weight (DW) were measured to assess phototrophic and whole biofilm biomass development over time. From the analysis of photosynthetic parameter variation with light intensity, temperature and flow rate, it was possible to identify the set of experimental values favoring biofilm photosynthetic activity. Biomass increased over time, especially at the highest irradiances, where substrata were fastly colonized and mature biofilms developed at all temperatures and flow conditions tested.
Semisoft cheese made from raw sheep's milk is traditionally and economically important in southern Europe. However, raw milk cheese is also a known vehicle of human listeriosis and contamination of sheep cheese with Listeria monocytogenes has been reported. In the present study, we have developed and applied a quantitative risk assessment model, based on available evidence and challenge testing, to estimate risk of invasive listeriosis due to consumption of an artisanal sheep cheese made with raw milk collected from a single flock in central Italy. In the model, contamination of milk may originate from the farm environment or from mastitic animals, with potential growth of the pathogen in bulk milk and during cheese ripening. Based on the 48‐day challenge test of a local semisoft raw sheep's milk cheese we found limited growth only during the initial phase of ripening (24 hours) and no growth or limited decline during the following ripening period. In our simulation, in the baseline scenario, 2.2% of cheese servings are estimated to have at least 1 colony forming unit (CFU) per gram. Of these, 15.1% would be above the current E.U. limit of 100 CFU/g (5.2% would exceed 1,000 CFU/g). Risk of invasive listeriosis per random serving is estimated in the 10 −12 range (mean) for healthy adults, and in the 10 −10 range (mean) for vulnerable populations. When small flocks (10–36 animals) are combined with the presence of a sheep with undetected subclinical mastitis, risk of listeriosis increases and such flocks may represent a public health risk.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
