Structure and activity of lacustrine sediment bacteria involved in nutrient and iron cycles

Knowledge about the bacterial community structure in sediments is essential to better design restoration strategies for eutrophied lakes. In that regard, the aim of this study was to quantify the abundance and activity of bacteria involved in nutrient and iron cycling in sediments from four Azorean lakes with distinct trophic states (Verde, Azul, Furnas and Fogo). Inferred from quantitative PCR, bacteria performing anaerobic ammonia oxidation, were the most abundant in the eutrophic lakes Verde, Azul and Furnas (4.5 % to 16.6 %), followed by nitrifying bacteria (0.8 % to 13.0 %), denitrifying bacteria (0.5 % to 6.8 %), iron-reducing bacteria (0.2 % to 1.4 %), and phosphorus-accumulating organisms (<0.3 %). In contrast, denitrifying bacteria dominated sediments from the oligo-mesotrophic lake Fogo (8.8 %). Activity assays suggested that bacteria performing ammonia oxidation (aerobic and anaerobic), nitrite oxidation, heterothrophic nitrate reduction, iron reduction and biological phosphorus storage/release were present and active in all Azorean lake sediments. The present work also suggested that the activity of denitrifying bacteria might contribute to the release of phosphorus from sediments.The authors are indebted and grateful to the Regional Department of Water Resources and Land Planning (Azores) for the grant (Contrato Excepcionado no. 4/2008/ DROTRH) and its staff (Dina Pacheco), and to Virgilio Cruz and Paulo Antunes (Geosciences Department, University of Azores) for the useful help in sediments' collection, to the technical staff of the Department of Environmental Engineering - DTU for chemical analysis, to Laurent Philippot (INRA - University of Burgundy) for positive controls for DNB, to Richard Glaven and Derek Lovley (Department of Microbiology, University of Massachusetts) for Geobacter strains, to Paul Bodelier, Marzia Milleto and Marion Meima (Netherlands Institute of Ecology, NIOO-KNAW) for SRB clones and to Yunhong Kong and Per Halkjaer Nielsen (Department of Life Sciences, Section of Environmental Engineering, Aalborg University) for PAO clones. The authors also acknowledge the Grant SFRH/BD/25639/2005 from the Foundation for Science and Technology/M.C.T.(Portugal) awarded to G. M. and a Marie Curie Excellence Award (EC FP6) to B.F.S

Exploring denitrifying communities in the environment

Denitrifiers are aerobically respiring bacteria that under anoxic conditions have the ability to switch to anaerobic respiration, so that nitrate and nitrite are stepwise reduced to nitric oxide, nitrous oxide and dinitrogen. Denitrifiers are a very diverse functional group with members from almost all phylogenetic bacterial groups. One aim of this thesis was to re-evaluate published primers targeting the functional genes, nirS, nirK and nosZ, encoding different enzymes in the denitrification pathway. New primer combinations for nirS and nosZ were designed, whereas the existing primers for nirK still seemed satisfactory. It was possible to PCR-amplify nirS genotypes from soil samples using the new nirS primer pair. In addition, denaturing gradient gel electrophoresis was introduced as a fingerprinting method for nirK- and nosZ-denitrifiers. The methods developed in this initial project were then used to study denitrifying communities in two environments where denitrification is especially important from a human perspective. In the first, methanol and ethanol were added to a wastewater treatment plant with an activated sludge process to increase the denitrification rate. As a result of the additions of external carbon sources the denitrifying communities altered their metabolic function, and specific nirS- and nirK-denitrifiers developed. In the second project, the nirK-denitrifiers were used as a model community to investigate the toxicity of the heavy metal silver to soil denitrifiers. The use of silver is increasing because of its well-known antimicrobial effects, and this may lead to increased environmental contamination. The addition of silver reduced activity and number of denitrifiers, whereas their diversity increased. Because of this demonstrated sensitivity, it is proposed that denitrifiers are suitable indicator organisms for environmental pollution. In conclusion, this thesis shows that molecular methods show great potential for investigating diversity of denitrifiers in various environments, much of which is yet to be discovered. However, in order to fully understand the ecology of denitrifiers, methods targeting the active organisms must be developed, and more denitrifiers must be isolated and characterised

Smärtskattningsskalor till för tidigt födda barn - En systematisk litteraturstudie

Bakgrund: Obehandlad smärta hos för tidigt födda barn kan leda till både omedelbara och långtgående negativa effekter. För att kunna ge barnen en adekvat smärtbehandling är det viktigt att regelbunden smärtskatta dem, men då de inte kan kommunicera verbalt är de beroende av att andra kan tolka deras smärtsignaler. Syfte: Att identifiera smärtskattningsskalor riktade mot för tidigt födda barn samt undersöka deras validitet och reliabilitet. Metod: En systematisk litteraturstudie med arton inkluderade artiklar. Resultat: Fjorton smärtskattningsskalor anpassade till för tidigt födda barn identifierades. Alla visade god eller mycket god reliabilitet. Gällande validitet skiljde det sig åt mellan de olika instrumenten. Slutsats: Det går inte att rekommendera en specifik smärtskattningsskala baserat på denna litteraturstudie. Det är därför viktigt att fortsätta undersöka de mest lovande i större, kliniska studier och säkerställa deras validitet, reliabilitet, klinisk användbarhet och relevans

Opioid-inducerad obstipation i samband med postoperativ smärtbehandling : Förekomst och förebyggande åtgärder

Objective: The objective was to examine the incidence of constipation, and the preventive measures taken in relation with postoperative pain treatment with opioids at two orthopaedic surgery wards. Methods: The participants were patients that had undergone surgery in the back, hip or thigh. They were selected through systematic selection and a total of 46 electronic health records were examined. The factors investigated and tested for correlation with constipation were the usage of laxatives, daily fluid-intake and early mobilisation. Results: Totally, 26.1 % of the patients became constipated, and laxatives were prescribed to 65.2 % of the patients. Doctors prescribed 53.3 % of the laxatives, nurses 33.3 % and for the remaining 13.3 % it was uncertain who had written the prescription. Usage of laxatives seemed to cause constipation (p=0,025), whereas there was no correlation between constipation and early mobilization. The documentation regarding daily fluid-intake was insufficient and no correlation test could be performed. Conclusions: This study failed to demonstrate that usage of laxatives and early mobilization prevents constipation in patients postoperatively treated with opioids. There was a need for increased education about constipation and its preventing measures for health care workers

Opioid-inducerad obstipation i samband med postoperativ smärtbehandling : Förekomst och förebyggande åtgärder

Objective: The objective was to examine the incidence of constipation, and the preventive measures taken in relation with postoperative pain treatment with opioids at two orthopaedic surgery wards. Methods: The participants were patients that had undergone surgery in the back, hip or thigh. They were selected through systematic selection and a total of 46 electronic health records were examined. The factors investigated and tested for correlation with constipation were the usage of laxatives, daily fluid-intake and early mobilisation. Results: Totally, 26.1 % of the patients became constipated, and laxatives were prescribed to 65.2 % of the patients. Doctors prescribed 53.3 % of the laxatives, nurses 33.3 % and for the remaining 13.3 % it was uncertain who had written the prescription. Usage of laxatives seemed to cause constipation (p=0,025), whereas there was no correlation between constipation and early mobilization. The documentation regarding daily fluid-intake was insufficient and no correlation test could be performed. Conclusions: This study failed to demonstrate that usage of laxatives and early mobilization prevents constipation in patients postoperatively treated with opioids. There was a need for increased education about constipation and its preventing measures for health care workers

Opioid-inducerad obstipation i samband med postoperativ smärtbehandling : Förekomst och förebyggande åtgärder

Objective: The objective was to examine the incidence of constipation, and the preventive measures taken in relation with postoperative pain treatment with opioids at two orthopaedic surgery wards. Methods: The participants were patients that had undergone surgery in the back, hip or thigh. They were selected through systematic selection and a total of 46 electronic health records were examined. The factors investigated and tested for correlation with constipation were the usage of laxatives, daily fluid-intake and early mobilisation. Results: Totally, 26.1 % of the patients became constipated, and laxatives were prescribed to 65.2 % of the patients. Doctors prescribed 53.3 % of the laxatives, nurses 33.3 % and for the remaining 13.3 % it was uncertain who had written the prescription. Usage of laxatives seemed to cause constipation (p=0,025), whereas there was no correlation between constipation and early mobilization. The documentation regarding daily fluid-intake was insufficient and no correlation test could be performed. Conclusions: This study failed to demonstrate that usage of laxatives and early mobilization prevents constipation in patients postoperatively treated with opioids. There was a need for increased education about constipation and its preventing measures for health care workers

Metabolic Profiles and Genetic Diversity of Denitrifying Communities in Activated Sludge after Addition of Methanol or Ethanol

External carbon sources can enhance denitrification rates and thus improve nitrogen removal in wastewater treatment plants. The effects of adding methanol and ethanol on the genetic and metabolic diversity of denitrifying communities in activated sludge were compared using a pilot-scale plant with two parallel lines. A full-scale plant receiving the same municipal wastewater, but without external carbon source addition, was the reference. Metabolic profiles obtained from potential denitrification rates with 10 electron donors showed that the denitrifying communities altered their preferences for certain compounds after supplementation with methanol or ethanol and that methanol had the greater impact. Clone libraries of nirK and nirS genes, encoding the two different nitrite reductases in denitrifiers, revealed that methanol also increased the diversity of denitrifiers of the nirS type, which indicates that denitrifiers favored by methanol were on the rise in the community. This suggests that there might be a niche differentiation between nirS and nirK genotypes during activated sludge processes. The composition of nirS genotypes also varied greatly among all samples, whereas the nirK communities were more stable. The latter was confirmed by denaturing gradient gel electrophoresis of nirK communities on all sampling occasions. Our results support earlier hypotheses that the compositions of denitrifier communities change during predenitrification processes when external carbon sources are added, although no severe effect could be observed from an operational point of view

Soil Resources Influence Spatial Patterns of Denitrifying Communities at Scales Compatible with Land Management▿ †

Knowing spatial patterns of functional microbial guilds can increase our understanding of the relationships between microbial community ecology and ecosystem functions. Using geostatistical modeling to map spatial patterns, we explored the distribution of the community structure, size, and activity of one functional group in N cycling, the denitrifiers, in relation to 23 soil parameters over a 44-ha farm divided into one organic and one integrated crop production system. The denitrifiers were targeted by the nirS and nirK genes that encode the two mutually exclusive types of nitrite reductases, the cd1 heme-type and copper reductases, respectively. The spatial pattern of the denitrification activity genes was reflected by the maps of the abundances of nir genes. For the community structure, only the maps of the nirS community were related to the activity. The activity was correlated with nitrate and dissolved organic nitrogen and carbon, whereas the gene pools for denitrification, in terms of size and composition, were influenced by the soil structure. For the nirS community, pH and soil nutrients were also important in shaping the community. The only unique parameter related to the nirK community was the soil Cu content. However, the spatial pattern of the nirK denitrifiers corresponded to the division of the farm into the two cropping systems. The different community patterns, together with the spatial distribution of the nirS/nirK abundance ratio, suggest habitat selection on the nirS- and nirK-type denitrifiers. Our findings constitute a first step in identifying niches for denitrifiers at scales relevant to land management