| 1. |
- Bastviken, David, 1971-, et al.
(författare)
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Methane as a source of carbon and energy for lake pelagic food webs
- 2003
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Ingår i: Ecology. - 0012-9658 .- 1939-9170. ; 84:4, s. 969-981
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Tidskriftsartikel (refereegranskat)abstract
- Water-column methane oxidation can represent a substantial carbon transformation pathway in lakes, and circumstantial evidence indicates that methane may be a potentially important source of carbon for pelagic food webs. We estimated methanotrophic bacterial production (MBP), methanotrophic bacterial growth efficiency (MBGE), heterotrophic bacterial production (HBP), primary production (PP), and the relative contribution of methanotrophic bacteria to overall bacterial biomass in three very different lakes during summer and winter. In addition, we measured stable carbon isotope ratios in particulate organic matter (POM), surface sediments, zooplankton, and methane. MBP corresponded to 0.3-7% of the organic C production by primary producers, and 0.5-17% of HBP during summer. During winter, MBP was 3-120% of HBP. MBP generally dominated the heterotrophic bacterial production at greater depths. Methanotrophic biomass was 3-11% of total bacterial biomass on a depth-integrated basis. Zooplankton were generally more depleted in 13C than POM. If phytoplankton d13C signatures were -35 to -30ë, such as the POM signals, observed zooplankton signatures could be explained by a fraction of 5-15% methanotrophic bacteria in their diet. The results indicate that methanotrophic bacteria can provide a significant food source for zooplankton, and that methane oxidation represents a potentially important benthic-pelagic carbon and energy link in many lakes, particularly during winter.
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| 2. |
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| 3. |
- Bergdahl, Ingvar A., et al.
(författare)
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Mercury in serum predicts low risk of death and myocardial infarction in Gothenburg women.
- 2013
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Ingår i: International archives of occupational and environmental health. - : Springer Science and Business Media LLC. - 1432-1246 .- 0340-0131. ; 86:1, s. 71-7
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Purpose Markers of mercury (Hg) exposure have shown both positive and negative associations with cardiovascular disease (CVD). We assessed the association between serum Hg (S–Hg) and risk of cardiovascular disease in a prospective population-based cohort, with attention to the roles of dental health and Wsh consumption. Methods Total mortality, as well as morbidity and mortality from acute myocardial infarction (AMI) and stroke, was followed up for 32 years in 1,391 women (initially age 38–60), in relation to S–Hg at baseline, using Cox regression models. Potential confounders (age, socioeconomic status, serum lipids, alcohol consumption, dental health, smoking, hypertension, waist-hip ratio, and diabetes) and other covariates (e.g., Wsh consumption) were also considered. Results Hazard ratios (HR) adjusted only for age showed strong inverse associations between baseline S–Hg and total mortality [highest quartile: hazard ratio (HR) 0.76; 95% conWdence interval (CI) 0.59–0.97], incident AMI (HR 0.56; CI 0.34–0.93), and fatal AMI (HR 0.31; CI 0.15–0.66). Adjustment for potential confounding factors, especially dental health, had a strong impact on the risk estimates, and after adjustment, only the reduced risk of fatal AMI remained statistically signiWcant. Conclusions There was a strong inverse association between Hg exposure and CVD. Likely, reasons are confounding with good dental health (also correlated with the number of amalgam Wllings in these age groups) and/or Wsh consumption. The results suggest potential eVects of dental health and/or Wsh consumption on CVD that deserve attention in preventive medicine.
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| 4. |
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| 5. |
- Börjesson, Gunnar, et al.
(författare)
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Methane oxidation in landfill cover soils, as revealed by potential oxidation measurements and phospholipid fatty acid analyses
- 1998
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Ingår i: Soil Biology and Biochemistry. - 0038-0717. ; 30:10-11, s. 1423-1433
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Tidskriftsartikel (refereegranskat)abstract
- Landfills account for ca. 10% of the annual global burden of atmospheric methane. Part of the efflux is mitigated by means of biological methane oxidation in the landfill covers. In this study, two types of landfill cover soils (mineral soil and sewage sludge) were compared with respect to methane emissions as well as potential methane oxidation capacity and the PLFA (phospholipid fatty acid) content of soil samples. Methane fluxes were lowest at a landfill site where wastes were covered with old sewage sludge. This site consumed atmospheric methane on most occasions. In incubated soil samples from the landfill cover composed of mineral soil, potential methane oxidation was most strongly correlated with the concentration of PLFA 18:1ω8, which is typical for type-II methanotrophic bacteria. In contrast, in samples from a landfill cover composed of fresh sewage sludge, methane oxidation was most strongly correlated with 16:1-PLFAs, indicating that type-I methanotrophs predominated, probably owing to nutritional conditions being more favourable in the sludge. The results also indicate that it takes a long time, i.e. several years, for methanotrophs to get well established in landfill cover soils.
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| 6. |
- Börjesson, Gunnar, et al.
(författare)
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Microbial oxidation of CH4 at high partial pressures in an organic landfill cover soil under different moisture regimes
- 1998
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Ingår i: FEMS Microbiology Ecology. - 0168-6496. ; 26:3, s. 207-217
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Tidskriftsartikel (refereegranskat)abstract
- The uptake and utilization of CH4 at high concentrations (5-18% vol.) and different soil moistures were followed for samples from a landfill cover soil with a high organic matter content. Measurements of the utilization of CH4 and O2, and production of CO2 indicated that the activity of methanotrophic organisms accounted for most of the O2 respiration. At water saturation, CH4 oxidation rates decreased with time, probably because NH4/+ accumulated. Denitrification rates, estimated based on both N2 and N2O production, were positively related to soil moisture and only slightly influenced by the extent of CH4 oxidation. Total phospholipid fatty acid concentrations increased, and concentrations of phospholipid fatty acids, typical for obligate methanotrophic bacteria (e.g. 16:1ω8 and 18:1ω8), increased in the CH4-amended samples, indicating growth of both type I and type II methanotrophs.
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| 7. |
- Eklind, Ylva, et al.
(författare)
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Carbon Turnover and Ammonia Emissions during Composting of Biowaste at Different Temperatures
- 2007
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Ingår i: Journal of Environmental Quality. - : Wiley. - 0047-2425 .- 1537-2537. ; 36:5, s. 1512-1520
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different process temperatures (40, 55, and 67°C) during composting of source-separated household waste were studied in a 200 L compost reactor at an oxygen concentration of 16%. The overall decomposition measured as carbon mineralization, decomposition of different carbon constituents, and the dynamics of nitrogen mineralization and the microbial community, are reported. Ammonia emissions at 67°C were more than double those at lower temperatures, and they were lowest at 40°C. The decomposition rate, measured as CO2 emission, was highest at 55°C. Decomposition of crude fat was slower at 40°C than at 55 and 67°C. The peak in microbial biomass was largest in the run at 40°C, where substantial differences were seen in the microbial community structure and succession compared to thermophilic temperatures. Biowaste composting can be optimized to obtain both a high decomposition rate and low ammonia emissions by controlling the process at about 55°C in the initial, high-rate stage. To reduce ammonia emissions it seems worthwhile to reduce the temperature after an initial high-temperature stage.
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| 8. |
- Håkansson, Sebastian, et al.
(författare)
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Domesticering av mikroorganismer
- 2011
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Ingår i: Genteknik som tar skruv. - 9789154060610 ; , s. 211-222
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Bokkapitel (populärvet., debatt m.m.)
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| 9. |
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| 10. |
- Johnsson, Anna-Ida, et al.
(författare)
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Development and evaluation of SCAR markers for a Pseudomonas brassicacearum strain used in biological control of snow mould
- 2009
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Ingår i: Biological Control. - : Elsevier BV. - 1049-9644 .- 1090-2112. ; 48, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- Biological control microorganisms have long been promoted as an alternative to conventional pesticides. Before registration of a microbial biocontrol product for commercial sale, it must be evaluated as regards potential spread and persistence after release. In this study, strainspecific sequence-characterized amplified region (SCAR) markers were developed to monitor the biocontrol candidate strain Pseudomonas brassicacearum MA250, which is effective against snow mould (Microdochium nivale). One SCAR marker, OPA2-73, was used in quantitative real-time PCR (Q-PCR) on samples from a climate chamber experiment in which winter wheat seeds were treated with the bacterium or a chemical control agent, or left untreated. The results showed that MA250 persisted for up to 3 weeks after sowing on the kernel residues and also colonized the roots of treated seedlings. Total MA250 cell numbers on biocontrol treated seedlings after three weeks were approximately 10(6) Cells, compared with the original inoculum of 10(6)-10(7) cells per seed. Corresponding cell numbers of MA250 on chemically treated and untreated seedlings were below the detection limit. This study shows that SCAR marker OPA2-73 is a specific and sensitive tool for monitoring the biocontrol microorganism MA250 in environmental samples. (C) 2008 Elsevier Inc. All rights reserved.
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| 11. |
- Johnsson, Anna-Ida, et al.
(författare)
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Fate and behaviour of a seed-applied Pseudomonas brassicacearum strain in a winter wheat field trial, as determined by analysis with SCAR markers
- 2012
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Ingår i: Biocontrol Science and Technology. - : Informa UK Limited. - 0958-3157 .- 1360-0478. ; 22, s. 379-392
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Tidskriftsartikel (refereegranskat)abstract
- The fate and behaviour of the seed-applied biocontrol strain Pseudomonas brassicacearum MA250 in a field trial with winter wheat was determined using sequence-characterised amplified region (SCAR) markers. Samples of below-ground plant parts from healthy and withered (due to snow mould infection) seedlings were collected approximately one and seven months after sowing, which was performed in early autumn. DNA was extracted from roots and remaining parts of seeds with adhering soil, and the abundance of the strain was determined in quantitative real-time PCR (qPCR) assays. The results show that the introduced strain persisted over the whole trial-period of seven months. On termination of the trial (after seven months) the below-ground plant parts of each plant housed 10(6)-10(7) cells, substantially less than the original approximately 10 9 cells inoculated onto the seed. In healthy seedlings, there was a shift in cell numbers from seeds to roots between the samplings, suggesting colonisation of the roots during this time. The results show that with sufficient attention given to analytical control measures and the possibility of resident background populations, SCAR markers in combination with qPCR provide valuable information regarding the fate and behaviour of biocontrol micro-organisms under field conditions.
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| 12. |
- Johnsson, Anna-Ida, et al.
(författare)
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Specific SCAR markers and multiplex real-time PCR for quantification of two Trichoderma biocontrol strains in environmental samples
- 2011
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Ingår i: BioControl. - : Springer Science and Business Media LLC. - 1386-6141 .- 1573-8248. ; 56, s. 903-913
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Tidskriftsartikel (refereegranskat)abstract
- Several strains from the genus Trichoderma (Ascomycetes, Hypocreales) are commercially used as biocontrol agents, e.g. in formulations containing the two Trichoderma strains IMI206039 (Hypocrea parapilulifera B.S. Lu, Druzhinina & Samuels) and IMI206040 (T. atroviride P. Karst). To quantify the presence of the two isolates after application, we developed primers for SCAR markers (Sequence-Characterised Amplified Region). In order to quantify both fungal strains simultaneously, we also designed fluorophore-labelled probes distinguishing the two strains, to be used in combination with the SCAR primers. In incubations of two different soils, artificially inoculated and maintained under controlled conditions, the quantification through amplification with the SCAR markers in qPCR and through colony-forming units from plate counting correlated well. Further tests of the markers on samples taken from a golf green treated with a product containing both strains indicated that the two biocontrol strains did not establish, either on the golf green or in the surrounding area.
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| 13. |
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| 14. |
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| 15. |
- Jönsson, Håkan, et al.
(författare)
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Minimera mängden producerat avfall
- 2003
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Ingår i: Miljömagasinet. ; 2003-02-21, s. 4-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 16. |
- Lagerlöf, Jan, et al.
(författare)
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Land-use intensification and agroforestry in the Kenyan highland: Impacts on soil microbial community composition and functional capacity
- 2014
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 82, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates microbial communities in soil from sites under different land use in Kenya. We sampled natural forest, forest plantations, agricultural fields of agroforestry farms, agricultural fields with traditional farming and eroded soil on the slopes of Mount Elgon, Kenya. We hypothesised that microbial decomposition capacity, biomass and diversity (1) decreases with intensified cultivation; and (2) can be restored by soil and land management in agroforestry. Functional capacity of soil microbial communities was estimated by degradation of 31 substrates on Biolog EcoPlates (TM). Microbial community composition and biomass were characterised by phospholipid fatty acid (PLFA) and microbial C and N analyses. All 31 substrates were metabolised in all studied soil types, i.e. functional diversity did not differ. However, both the substrate utilisation rates and the microbial biomass decreased with intensification of land use, and the biomass was positively correlated with organic matter content. Multivariate analysis of PLFA and Biolog EcoPlate (TM) data showed clear differences between land uses, also indicated by different relative abundance of PLFA markers for certain microorganism groups. In conclusion, our results show that vegetation and land use control the substrate utilisation capacity and microbial community composition and that functional capacity of depleted soils can be restored by active soil management, e. g. forest plantation. However, although 20-30 years of agroforestry farming practises did result in improved soil microbiological and chemical conditions of agricultural soil as compared to traditional agricultural fields, the change was not statistically significant. (C) 2014 Elsevier B. V. All rights reserved.
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| 17. |
- Lankinen, Åsa, et al.
(författare)
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Fokusprojekt Lågriskmedel i växtskyddet
- 2019
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Rapport (populärvet., debatt m.m.)abstract
- Fokusgruppens syfte har varit att definiera kunskapsluckor avseende den praktiska användningen och implementeringen av alternativa medel med låg risk för bekämpning av skadegörare och sjukdomar inom jordbruk, trädgårdsodling och skogsbruk. Vi har utgått från en bred definition av medel med låg risk, som har omfattat både allmänkemikalier och växtskyddsmedel med låg risk (enligt gällande EU-lagstiftning). Trots att det idag finns ett ökat behov av alternativa verktyg inom växtskyddet och politiska mål om minimerad användning av kemiska medel, så är användningen av alternativa bekämpningsmedel i fältodlade grödor mycket begränsad. • En viktig faktor som styr och begränsar tillgängligheten av alternativa medel är EU-lagstiftningen för godkännande av dessa medel. För att kunna registrera ett medel behövs en investering från det företag som ansöker om godkännande, vilket kan vara en anledning till att medel inte blir tillgängliga på marknaden. En annan lagteknisk begränsning är ogynnsamma skatteregler för dessa medel. • Från ett användarperspektiv är bristande kunskap om hur effektiva dessa medel är, hur man bäst applicerar dem samt hur de kan integreras i befintliga växtskyddsstrategier en bidragande orsak till att de inte används fullt ut. • Rådgivningen pekar också på en otydlighet om vilka medel som får användas speciellt i ekologisk produktion och att användningen missgynnas av höga priser i kombination med en osäkerhet om hur effektiva dessa medel är. • I Jordbruksverkets rapport ”Hinder för ökad användning av alternativa bekämpningsmedel” (SJV, Rapport 2019:3), som medlemmar av fokusgruppen har varit med att skriva, är ett av förslagen en utökad rådgivningsverksamhet. Detta eftersom informationsinsatser och aktiv rådgivning kan påverka hur snabbt odlare accepterar och börjar använda ett växtskyddsmedel, speciellt om det har nya egenskaper (och en ny verkningsmekanism). Forskning visar att en ny åtgärd/metod inte bara ska Sammanfattning och slutsatser 5 passa in i befintliga verksamheter utan också passa med attityd och värderingar hos användaren. • Från ett forskningsperspektiv kan vi se ett klart behov av tillämpningsnära forskning framför allt för att få en ökad kunskap om hur alternativa bekämpningsmedel kan integreras i befintliga växtskyddsstrategier. En utmaning är den begränsade mängd forskningsmedel som finns att söka för denna typ av forskning. • Forskningen är ofta väldigt uppdelad mellan agrikultur, hortikultur och skogsbruk. Här skulle man kunna dra nytta av kunskap inom respektive system eftersom vissa aspekter är generella mellan olika system, åtminstone för vissa grödor/träd. • Från ett internationellt perspektiv kan vi se vinster med ett bättre samarbete med närliggande länder, tex Plant Biologicals Network (PBN) som koordineras från Danmark, men även engagemang inom det vidare EUperspektivet (bla lagar). • Ytterligare en slutsats från fokusgruppens arbete är att växtskyddsforskningen på SLU behöver samordnas bättre, tex genom att knyta samman de kompetenscentrum som finns idag – CBC och CKB – med nya strukturer som skulle kunna fokusera på i) analys av växtskadegörare och ii) lågrisk-metoder och hur dessa kan spela en roll i integrerat växtskydd (IPM). • ygarbeta tillsammans för att få till en bra samverkan och kunskapsutbyte.
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| 18. |
- Lau, Danny C P, et al.
(författare)
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Autochthonous resources are the main driver of consumer production in dystrophic boreal lakes
- 2014
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 95, s. 1506-1519
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Tidskriftsartikel (refereegranskat)abstract
- Dystrophic lakes are widespread in temperate regions and intimately interact with surrounding terrestrial ecosystems in energy and nutrient dynamics, yet the relative importance of autochthonous and allochthonous resources to consumer production in dystrophic lakes remains controversial. We argue that allochthonous organic matter quantitatively dominates over photosynthetic autotrophs in dystrophic lakes, but that autotrophs are higher in diet quality and more important for consumers as they contain essential polyunsaturated fatty acids (PUFA). In a field study, we tested the hypotheses that (1) autochthonous primary production is the main driver for consumer production, despite being limited by light availability and low nutrient supplies, and greater supply of allochthonous carbon, (2) the relative contribution of autotrophs to consumers is directly related to their tissue PUFA concentrations, and (3) methane-oxidizing bacteria (MOB) provide an energy alternative for consumers.Pelagic and benthic consumer taxa representing different trophic levels were sampled from five dystrophic lakes: isopod Asellus aquaticus, megalopteran Sialis lutaria, dipteran Chaoborus flavicans, and perch Perca fluviatilis. Based on carbon and nitrogen stable isotopes, the relative contributions of autochthonous (biofilms and seston) and allochthonous (coarse particulate and dissolved organic matter) resources and MOB to these taxa were 47-79%, 9-44% and 7-12% respectively. Results from fatty acid (FA) analyses show that the relative omega 3-FA and PUFA concentrations increased with trophic level (Asellus < Sialis and Chaoborus < Perca). Also, eicosapentaenoic-acid (EPA), omega 3-FA and PUFA concentrations increased with the autochthonous contribution in consumers, i.e., a 47-79% biofilm and/or seston diet resulted in tissue EPA of 4.2-18.4, omega 3 FAs of 11.6-37.0 and PUFA of 21.6-61.0 mg/g dry mass. The results indicate that consumers in dystrophic lakes predominantly rely on energy from autotrophs and that their PUFA concentrations are dependent on the relative contribution of these autochthonous resources. The limited energy support from MOB suggests they are not negligible and are potentially an integral part of the food webs. Our findings show that autochthonous resources are the main driver of secondary production even in dystrophic lakes and offer new insights into the functioning of these ecosystems.
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| 19. |
- Melin, Petter, et al.
(författare)
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Biological preservation of plant derived animal feed with antifungal microorganisms : safety and formulation aspects
- 2007
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Ingår i: Biotechnology letters. - Dordrecht, Netherlands : Springer. - 0141-5492 .- 1573-6776. ; 29:8, s. 1147-1154
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Forskningsöversikt (refereegranskat)abstract
- During storage of moist animal feed, growth of detrimental fungi causing spoilage, or being mycotoxigenic or pathogenic, is a severe problem. Addition of biopreservative yeasts or lactic acid bacteria can significantly reduce this problem. However, their use requires several careful considerations. One is the safety to the animal, humans and the environment, tightly connected to legal aspects and the need for pre-market authorisation when supplementing feed with microorganisms. Although both yeasts and lactic acid bacteria are considered comparatively safe organisms due to low production of toxic metabolites, it is of great importance to understand the mechanisms behind the biopreservative abilities. Another important issue concerns practical aspects, such as the economic production of large amounts of the organisms and the development of a suitable formulation giving the organisms a long shelf life. These aspects are discussed and a recommendation of this review is that both safety and formulation aspects of a specific microbe should be considered at an early stage in the selection of new organisms with biopreservation potential.
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| 20. |
- Nyberg, Karin, et al.
(författare)
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Response of Induced Perturbation on Replicating beta-Proteobacterial Ammonia-Oxidizing Populations in Soil
- 2012
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 63, s. 701-709
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Tidskriftsartikel (refereegranskat)abstract
- The short-term response of induced perturbation by 4-ethylphenol on beta-proteobacterial ammonia oxidizers (beta-AOB) was investigated in two soils with initial differences in community structure. The hypotheses were that short-term effects of a disturbance of the AOB community is best monitored by specifically looking at the active populations and that soils with dissimilar active AOB populations would display different degree of resistance or resilience. Two soils from a previously characterized long-term field study fertilized with manure or sewage sludge was used. Soil microcosms were incubated in the laboratory over 15 days. The substrate-induced ammonia oxidation was measured, and the composition of beta-AOB communities was determined by PCR-DGGE of specific beta-AOB 16S rRNA gene fragments. Actively replicating members of the beta-AOB were distinguished by the use of bromodeoxyuridine (BrdU) immunocapture. This approach demonstrated that only a minor fraction of the total AOB community was active. Exposure to 4-ethylphenol resulted in approximately 90% lowered substrate-induced ammonia oxidation rates in both soils. This activity inhibition was not accompanied by shifts in beta-AOB community structure when total beta-AOB DNA was studied. By contrast, changes were seen in the DGGE banding pattern of the BrdU-labeled community DNA after 4-ethylphenol addition in the manure-fertilized soil. In the sewage sludge fertilized soil, the banding pattern of the BrdU-labeled beta-AOB remained unchanged, but bands were weaker after the disturbance. In conclusion, it was shown that BrdU immunocapture was applicable to detect shifts in community composition among replicating beta-AOB populations in soil. However, this was not reflected by the soils' ammonia oxidation capacity to resist to or recover from the induced perturbation suggesting that rapid population shifts may not influence soil functioning in a short-term perspective.
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| 21. |
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| 22. |
- Sanseverino, Angela M, et al.
(författare)
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Methane Carbon Supports Aquatic Food Webs to the Fish Level
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- Large amounts of the greenhouse gas methane (CH4) are produced by anaerobic mineralization of organic matter in lakes. In spite of extensive freshwater CH4 emissions, most of the CH4 is typically oxidized by methane oxidizing bacteria (MOB) before it can reach the lake surface and be emitted to the atmosphere. In turn, it has been shown that the CH4-derived biomass of MOB can provide the energy and carbon for zooplankton and macroinvertebrates. In this study, we demonstrate the presence of specific fatty acids synthesized by MOB in fish tissues having low carbon stable isotope ratios. Fish species, zooplankton, macroinvertebrates and the water hyacinth Eichhornia crassipes were collected from a shallow lake in Brazil and analyzed for fatty acids (FA) and carbon stable isotope ratios (delta C-13). The fatty acids 16:1 omega 8c, 16:1 omega 8t, 16:1 omega 6c, 16:1 omega 5t, 18:1 omega 8c and 18:1 omega 8t were used as signature for MOB. The delta C-13 ratios varied from -27.7 parts per thousand to -42.0 parts per thousand and the contribution of MOB FA ranged from 0.05% to 0.84% of total FA. Organisms with higher total content of MOB FAs presented lower delta C-13 values (i.e. they were more depleted in C-13), while organisms with lower content of MOB signature FAs showed higher delta C-13 values. An UPGMA cluster analysis was carried out to distinguish grouping of organisms in relation to their MOB FA contents. This combination of stable isotope and fatty acid tracers provides new evidence that assimilation of methane-derived carbon can be an important carbon source for the whole aquatic food web, up to the fish level.
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| 23. |
- Schneider, Salome, et al.
(författare)
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Chromosome-Directed PCR-Based Detection and Quantification of Bacillus cereus Group Members with Focus on B. thuringiensis Serovar israelensis Active against Nematoceran Larvae
- 2015
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 81:15, s. 4894-4903
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Tidskriftsartikel (refereegranskat)abstract
- Bacillus thuringiensis serovar israelensis is a wide-spread soil bacterium affiliated with the B. cereus group (Bcg) and is widely used in biocontrol products applied against mosquito and black fly larvae. For monitoring and quantification of applied B. thuringiensis serovar israelensis and its effect on indigenous B. thuringiensis serovar israelensis and Bcg assemblages, efficient and reliable tools are essential. The abundance and properties of B. thuringiensis serovar israelensis strains in the environment traditionally have been investigated with cultivation-dependent techniques, which are hampered by low sensitivity and the morphological similarity between B. cereus and B. thuringiensis. Currently available PCR-based detection and quantification tools target markers located on plasmids. In this study, a new cultivation-independent PCR-based method for efficient and specific quantification of B. thuringiensis serovar israelensis and Bcg is presented, utilizing two sets of PCR primers targeting the bacterial chromosome. Sequence database searches and empirical tests performed on target and nontarget species, as well as on bulk soil DNA samples, demonstrated that this diagnostic tool is specific for B. thuringiensis serovar israelensis and Bcg. The method will be useful for comparisons of Bcg and B. thuringiensis serovar israelensis abundances in the same samples. Moreover, the effect of B. thuringiensis serovar israelensis-based insecticide application on the total Bcg assemblages, including indigenous populations, can be investigated. This type of information is valuable in risk assessment and policy making for use of B. thuringiensis serovar israelensis in the environment.
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| 24. |
- Schneider, Salome, et al.
(författare)
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Do Multi-year Applications of Bacillus thuringiensis subsp israelensis for Control of Mosquito Larvae Affect the Abundance of B-cereus Group Populations in Riparian Wetland Soils?
- 2017
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Ingår i: Microbial Ecology. - : SPRINGER. - 0095-3628 .- 1432-184X. ; 74:4, s. 901-909
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Tidskriftsartikel (refereegranskat)abstract
- Bacillus thuringiensis subsp. israelensis (Bti) is a soil-borne bacterium affiliated to the Bacillus cereus group (Bcg) and has been used in biocontrol products against nematoceran larvae for several decades. However, knowledge is limited on whether long-term Bti application can affect the structure of indigenous communities of Bcg and the overall abundance of Bti. Using species- and group-specific quantitative PCR assays, we measured the Bcg- and Bti-abundances in riparian wetlands in the River Dalalven floodplains of central Sweden. On five occasions during one vegetative season, soil samples were collected in alder swamps and wet meadows which had been treated with Bti for mosquito larvae control during the preceding 11 years, as well as in untreated control sites and well-drained forests in the same area. The average abundance of Bcg in alder swamps was around three times higher than in wet meadows. Across all sites and habitats, the Bti treatments had no effect on the Bcg-abundance, whereas the Bti-abundance was significantly higher in the treated than in the control sites. However, for individual sampling sites, abundances of Bti and Bcg were not correlated with the number of Bti applications, indicating that added Bti possibly influenced the total population of Bti in the short term but had only a limited effect in the longer term. The findings of this study increase the understanding of the ecology of Bti applications for mosquito control, which can facilitate environmental risk assessment in connection with approval of microbiological control agents.
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| 25. |
- Steger, Kristin, et al.
(författare)
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Development of compost maturity and Actinobacteria populations during full-scale composting of organic household waste
- 2007
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 103:2, s. 487-498
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: This study investigates changes in microbiological and physicochemical parameters during large-scale, thermophilic composting of a single batch of municipal organic waste. The inter-relationships between the microbial biomass and community structure as well as several physicochemical parameters and estimates of maturation were evaluated. METHODS AND RESULTS: Analyses of signature fatty acids with the phospholipid fatty acid and ester-linked methods showed that the total microbial biomass was highest during the early thermophilic phase. The contribution of signature 10Me fatty acids from Actinobacteria indicated a relatively constant proportion around 10% of the microbial community. However, analyses of the Actinobacteria species composition with a PCR-denaturing gradient gel electrophoresis approach targeting 16S rRNA genes demonstrated clear shifts in the community structure. CONCLUSIONS: This study demonstrates that compost quality, particularly maturity, is linked to the composition of the microbial community structure, but further studies in other full-scale systems are needed to validate the generality of these findings. SIGNIFICANCE AND IMPACT OF THE STUDY: The combination of signature lipid and nucleic acid-based analyses greatly expands the specificity and the scope for assessing the microbial community composition in composts. The results presented in this study give new information on how the development of the compost microbial community is connected to curing and maturation in the later stages of composting, and emphasizes the role of Actinobacteria in this respect.
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