Blar i forfatter Artikler, rapporter og annet (Norges fiskerihøgskole) "Dalheim, Lars"

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    • Inclusion of photoautotrophic cultivated diatom biomass in salmon feed can deter lice 

      Eilertsen, Hans Christian; Elvevoll, Edel O.; Giæver, Ingeborg Hulda; Svenning, Jon Brage; Dalheim, Lars; Svalheim, Ragnhild Aven; Vang, Birthe; Siikavuopio, Sten Ivar; Dragøy, Ragnhild; Ingebrigtsen, Richard Andre; Hansen, Espen Holst; Hustad, Anette; Eilertsen, Karl-Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-29)
      The aim of this study was to evaluate the potential of diatom (microalgae) biomass as a lice-reducing ingredient in salmon feed. The original hypothesis was based on the fact that polyunsaturated aldehydes (PUAs), e.g. 2-trans, 4-trans decadenial (A3) produced by diatoms can function as grazing deterrents and harm copepod development. Salmon lice (Lepeophtheirus salmonis) is a copepod, and we intended ...

    • Lipid yield from the diatom Porosira glacialis is determined by solvent choice and number of extractions, independent of cell disruption 

      Svenning, Jon Brage; Dalheim, Lars; Vasskog, Terje; Vang, Birthe; Matricon, Lucie; Olsen, Ragnar Ludvig (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-17)
      Cell wall disruption is necessary to maximize lipid extraction yields in conventional species of mass-cultivated microalgae. This study investigated the effect of sonication, solvent choice and number of extractions on the lipid yield, lipid class composition and fatty acid composition of the diatom <i>Porosira glacialis</i>. For comparison, the diatom <i>Odontella aurita</i> and green alga <i>Chlorella ...

    • Mass Cultivation of Microalgae: I. Experiences with Vertical Column Airlift Photobioreactors, Diatoms and CO2 Sequestration 

      Eilertsen, Hans Christian; Eriksen, Gunilla; Bergum, John-Steinar; Strømholt, Jo; Elvevoll, Edel O.; Eilertsen, Karl-Erik; Heimstad, Eldbjørg Sofie; Giæver, Ingeborg Hulda; Israelsen, Linn; Svenning, Jon Brage; Dalheim, Lars; Osvik, Renate Døving; Hansen, Espen Holst; Ingebrigtsen, Richard Andre; Aspen, Terje M; Wintervoll, Geir-Henning (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-17)
      From 2015 to 2021, we optimized mass cultivation of diatoms in our own developed vertical column airlift photobioreactors using natural and artificial light (LEDs). The project took place at the ferrosilicon producer Finnfjord AS in North Norway as a joint venture with UiT—The Arctic University of Norway. Small (0.1–6–14 m<sup>3</sup>) reactors were used for initial experiments and to produce inoculum ...

    • Microbial Community Dynamics during a Harmful Chrysochromulina leadbeateri Bloom in Northern Norway 

      Aalto, Nerea Johanna; Schweitzer, Hannah; Grann-Meyer, Erlend; Krsmanovic, Stina; Svenning, Jon Brage; Dalheim, Lars; Petters, Sebastian; Ingebrigtsen, Richard Andre; Hulatt, Christopher Jonathan; Bernstein, Hans Christopher (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-09)
      A harmful algal bloom occurred in late spring 2019 across multiple, interconnected fjords and bays in northern Norway. The event was caused by the haptophyte Chrysochromulina leadbeateri and led to severe fish mortality at several salmon aquaculture facilities. This study reports on the spatial and temporal succession dynamics of the holistic marine microbiome associated with this bloom by relating ...

    • Protein determination - Method matters 

      Mæhre, Hanne K.; Dalheim, Lars; Edvinsen, Guro K.; Jensen, Ida-Johanne; Elvevoll, Edel O.; Jensen, Ida-Johanne (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-01)
      The reported protein content of foods depends on the analytical method used for determination, making a direct comparison between studies difficult. The aim of this study was to examine and compare protein analytical methods. Some of these methods require extraction preceding analysis. The efficacy of protein extraction differs depending on food matrices and thus extraction yield was determined. ...

    • Stability of lipids during wet storage of the marine diatom Porosira glacialis under semi-preserved conditions at 4 and 20 °C 

      Dalheim, Lars; Svenning, Jon Brage; Vasskog, Terje; Eilertsen, Hans Christian; Olsen, Ragnar Ludvig (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-17)
      Cultivation of diatoms may help alleviate the pressure on wild fish stocks for marine nutrient availability in aquaculture feed and for human consumption. However, the lipids in microalgae biomass are easily deteriorated, both trough lipolysis and degradation of polyunsaturated fatty acids (PUFA). Proper storage conditions are therefore necessary to maintain the lipid quality. Additionally, the ...

    • Temperature dependent growth rate, lipid content and fatty acid composition of the marine cold-water diatom Porosira glacialis 

      Svenning, Jon Brage; Dalheim, Lars; Eilertsen, Hans Christian; Vasskog, Terje (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-27)
      In this study, the northern cold-water marine diatom <i>Porosira glacialis</i> was cultivated in a pilot-scale mass cultivation system at 5 different temperatures (−2 to 12 °C), in order to evaluate temperature-dependent growth rate (in vitro Chl <i>a</i>), lipid content (Folch's method) and fatty acid (FA) composition (GC–MS) in the exponential growth phase. We found that <i>P. glacialis</i> has a ...