Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2010
Abstract
The water quality in the western part of Lake Vansjø in south eastern Norway is classified as very poor due to excessive growth of blue green algae. It has been shown that phosphorus (P) losses are high from a subcatchment where potatoes and vegetables are grown on 25 % of the agricultural area. The water quality of the lake is of great concern because it is the drinking water reservoir of 60.000 inhabitants and an important recreation area for people living in the area. An integrated project funded by the government was started in 2008 in order to improve the water quality of the lake. Within this project, the public agricultural management, agricultural advisors, farmers and the Norwegian Institute for Agricultural and Environmental Research (Bioforsk) collaborate to attain the target of improved water quality. The farmers are encouraged to sign a contract where they will receive a financial support for covering extra costs for committing to a set of restrictions and mitigation options aiming at reduced P losses. Vegetable- and potato fields give large challenges when aiming at reduced P losses. A large part of the research activity is therefore related to possible mitigation options on these fields, e.g. effect of reduced P fertilization on yields and quality of bulb onion (Allium cepa), carrots (Daucus carota) and white cabbage (Brassica oleracea var. capitata alba), and evaluation of catch crops as a mitigation option for reduced soil erosion from these fields. Development of constructed wetlands to include filters that adsorb P and measurement of P losses through tile drains are also included in the project.
Authors
Hsin-Ho Huang Daniel Camsund Peter Lindblad Thorsten HeidornAbstract
Cyanobacteria are suitable for sustainable, solar-powered biotechnological applications. Synthetic biology connects biology with computational design and an engineering perspective, but requires efficient tools and information about the function of biological parts and systems. To enable the development of cyanobacterial Synthetic Biology, several molecular tools were developed and characterized: (i) a broad-host-range BioBrick shuttle vector, pPMQAK1, was constructed and confirmed to replicate in Escherichia coli and three different cyanobacterial strains. (ii) The fluorescent proteins Cerulean, GFPmut3B and EYFP have been demonstrated to work as reporter proteins in cyanobacteria, in spite of the strong background of photosynthetic pigments. (iii) Several promoters, like P(rnpB) and variants of P(rbcL), and a version of the promoter P(trc) with two operators for enhanced repression, were developed and characterized in Synechocystis sp. strain PCC6803. (iv) It was shown that a system for targeted protein degradation, which is needed to enable dynamic expression studies, is working in Synechocystis sp. strain PCC6803. The pPMQAK1 shuttle vector allows the use of the growing numbers of BioBrick parts in many prokaryotes, and the other tools herein implemented facilitate the development of new parts and systems in cyanobacteria.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
2009
Abstract
No abstract has been registered
Abstract
Due to the exponential increase in production and marketing of engineered nanomaterials, concerns are raised about their inevitable spreading in the environment. Soils, with their high proportion of solid phase, are likely to constitute the major ultimate sink for engineered nanoparticles (ENPs). Regrettably, data are scarce on the potential environmental risks of ENPs on soil ecosystems. The main reason for this key knowledge gap was the lack of methodologies able to trace the ENPs in complex environmental matrices like soils, which already contain a high background of natural nanoparticles (e.g. clays, organic matter, iron oxides). Using neutron activation as a tracer technique enabled us to overcome this hurdle: neutron activated ENPs can readily be quantified by gamma spectrometry, in all kind of samples, including living organisms. Here we examined the uptake and excretion kinetics of cobalt (Co-NPs, APS 3.9 ± 0.8 nm) and silver nanoparticles (Ag-NPs, APS 20.2 ± 2.5 nm) in the earthworm Eisenia fetida, as well as their internal distribution within worms. We compared the uptake, retention time and internal ditribution of Co-NPs and Ag-NPs with those of soluble salts of cobalt and silver. Earthworms were fed over a 28d period with horse manure contaminated with either neutron activated Co-NPs and Ag-NPs, or Co and Ag salts spiked with the radiotracers 60Co and 110mAg. Accumulation and excretion kinetics were assessed by gamma spectrometry on living earthworms along a three month period for silver treatments and a five month period for cobalt treatments. The patterns of accumulation were highly different for cobalt and silver. The concentration ratios [(Bq/g worm) / (Bq/g food)] after 28d uptake were 0.93 ± 0.36 and 2.02 ± 0.65 for Co-NP and Co2+, respectively, while corresponding values for Ag-NPs and Ag+ were 0.015 ± 0.016 and 0.054 ± 0.024, respectively. Almost all absorbed Co-NPs and Co2+ remained within the worms four months after transfer to clean soil, while Ag concentration ratios fell to almost zero within a few days. We investigated futher the distribution of Co-NPs and Co2+ in worms bodies by coupling autoradiography images of worm transects and gamma spectrometry on individual organs. The body wall, mainly composed of muscular fibers, and the reproductive organs (e.g. spermathecae and seminal vesicles) accumulated lower amounts of cobalt than the digestive tract. By far, the highest accumulation was found in the blood, namely in the pseudo-hearts.
Abstract
No abstract has been registered
Abstract
Denitrification is a key ecosystem process which is essential to avoid massive enrichment of nitrate in surface and ground water. A rather narrow group of bacteria are able to carry out denitrification, and they are known to be sensitive to environmentally toxic pollutants like e.g. heavy metals. Since these microorganisms carry out a key ecosystem function, they are strong candidates for testing and monitoring environmental effects of toxic substances likely to reach the soil environment. We conducted a series of experiments where either a pure strain of a denitrifying bacterium (Paracoccus denitrificans) or intact soil microbial communities containing indigenous denitrifiers were subjected to different types of silver nanoparticles (average particle size 20 and 1 nm) at a wide range of concentrations. The results showed that the smallest particles were far more toxic than the larger ones on a mass basis and completely killed off denitrifying bacteria in vitro at concentrations as low as 100 ppb. When soil was present, this concentration had no effect on respiration and even the far more sensitive process of denitrification, measured as production of the gases NO, N2O and N2, was unaffected. Results from experiments that are under way will also be presented. Here threshold levels for inhibition of denitrification by P. denitrificans and intact microbial communities are established for the two types of silver nanoparticles and where toxicity is compared when expressed on a mass basis vs. a surface area basis. Also the sensitivity of the different steps in the denitrification process will be compared and related to corresponding data for dissolved metals. The perspectives for using denitrification impediment as a way to assess ecotoxicity at a functional level will be discussed.
Abstract
Silver nanoparticles constitute one of the most common nanomaterials used in consumer products today, and the volumes used are increasing dramatically. Silver is an element known for its acute toxicity to both prokaryotes and a range of aquatic organisms. While ecotoxicity studies on nano-sliver is being studied at species level for some aquatic organisms, corresponding studies on terrestrial organisms are lagging behind. Also, studies targeting functional endpoints rather than purely physiological aspects are lacking. We have compared two types of nano-silver differing in average particle size (1 and 20 nm) with respect to their inhibitory effects on a pure strain of the soil bacterium Paracoccus sp. Which is an efficient denitrifyer capable of transforming NO3 into N2. This process is an important step in the biogeochemical cycling of N, and one that may potentially produce large amounts of the potent green house gas N2O if impeded by environmental pollutants. The results show that nano-silver is highly toxic to denitrifying bacteria and that low amounts severely affect the process of denitrification. Studies using indigenous denitrifying bacterial communities incubated in the presence of different concentrations of nano-silver in soil slurries are under way and will provide data where soil constituents affect the bioavailability nano-silver in a close to realistic exposure scenario. The implications of the relationship between toxicity levels in pure cultures and soil slurries will be discussed regarding the bioavailability of nanoparticles as pollutants in terrestrial environments.
Abstract
Due to the exponential increase in production of engineered nanomaterials, concerns are raised about their inevitable spreading and fate in the environment. In this study we examined the uptake and excretion kinetics of cobalt and silver nanoparticles (NPs) in Eisenia fetida, as well as their internal distribution within earthworms. We hypothesised that the uptake, retention time and internal distribution of cobalt and silver depend on their speciation, i.e. whether they are absorbed as ions or nanoparticles. Nanoparticles were subjected to neutron activation prior to the experiment, in order to facilitate tracing and quantification in earthworms by gamma counting and autoradiography. Ions and NPs were added to the food, horse manure (HM). The treatments were Co2+ 0.70 µg/kg HM, CoNP 0.69 mg/kg HM, Ag+ 0.54 mg/kg HM, AgNP 0.45 mg/kg HM, and control. The experiment followed the OECD guidelines, with one month uptake and two months excretion for silver treatments, and four months excretion for cobalt treatments. The patterns of accumulation were highly different for cobalt and silver. The concentration ratios (Bq/g worm / Bq/g food) after one month uptake were 0.93 ± 0.36 and 2.02 ± 0.65 for CoNP and Co2+ respectively, and almost all absorbed CoNP and Co2+ remained within the worms after 4 months excretion. The Ag concentration ratios after one month uptake were 0.015 ± 0.016 and 0.054 ± 0.024 for AgNP and Ag+ respectively, with a subsequent excretion of almost all AgNP and Ag+ within a few days. In addition to information on uptake and excretion kinetics, gamma counting on individual organs, coupled to autoradiography on worm transects gave information on distribution of cobalt and silver NPs within the body, and the target organs for these NPs.