Browsing by Subject "Phaeodactylum tricornutum"
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Item Lipid analysis of Phaeodactylum tricornutum in response to trans trans 2,4 decadienal stress(2011-08) Byrwa, Brian Christopher; Mehdy, Mona Cynthia, 1955-; Sathasivan, KanagasabapathiConsidering the nature of increasing global temperatures associated with elevated atmospheric carbon dioxide levels as a result of increased demand for energy, it is notable to consider viable options to reduce the strain that these increased carbon dioxide emissions are having on the overall impact of the global climate. Phaeodactylum tricornutum, a marine phytoplankton may be utilized to this end. Its unique ability to increase lipid production under environmental stress conditions, in particular those lipids that can easily be converted into biodiesel, make it an ideal candidate for this use. Here, we examine the effects of trans trans 2,4 decadienal (or DD for short), an aldehyde that is known to induce cell death in the diatom at high concentrations, as they relate to changes in the lipid biosynthesis pathway. 100 ml Axenic cultures of the diatom P. tricornutum were grown to exponential stage, harvested and treated with decadienal at a concentration of 5[mu]g/ml to determine effects on lipid production after 24 hours. Qualitative analysis undertaken using Nile red staining of treated and untreated cells indicated increased fluorescence of treated cells compared to unstained water controls, however this increase may not be attributable to increased lipid production due to the fact that cells were unfixed and must be verified through other means. Initial attempts to verify this finding through thin layer chromatography and qPCR were inconclusive.Item Rheology of algae slurries(2010-12) Bolhouse, Angel Michele; Berberoglu, Halil; Ferron, RaissaThis thesis reports the rheological properties of algae slurries as a function of cell concentration for three microalgae species: Nannochloris sp.,Chlorella vulgaris, and Phaeodactylum tricornutum. Rheological properties ofalgae slurries have a direct impact on the agitation and pumping power requirements as well as process design for producing algal biofuels. This study measures the rheological properties of eight diff erent concentrations of each species ranging from 0.5 to 80 kg dry biomass/m³. Strain-controlled steady rate sweep tests were performed for each sample with an ARES-TA rheometer using a double wall couette cup and bob attachment. Shear rates ranged from 5 - 270 s⁻¹, corresponding to typical expected conditions. The results showed that Nannochloris sp. slurry behaved as a Newtonian fluid for concentrations up to 20 kg/m³. Samples with concentrations above 40 kg/m³ behaved as a shear thinning non-Newtonian fluid. The effective viscosity increased with increased biomass concentration for a maximum value of 3.3x10⁻³ Pa-s. Similarly, C. vulgaris slurry behaved as a Newtonian fluid with concentrations of up to 40 kg/m³, above which it displayed a shear thinning non-Newtonianf behavior and a maximum eff ective viscosity of 3.5x10⁻² Pa-s. On the other hand, P. tricornutum slurry demonstrated solely Newtonian fluid behavior, with the dynamic viscosity increasing with increasing biomass concentration for a maximum value of 3.2x10⁻³ Pa-s. The maximum observed e ffective viscosity occurred at a concentration of 80 kg/m³ for all three species. Moreover, an energy analysis was performed where a non-dimensional bioenergy transport e ffectiveness was de termined as the ratio of the energy content of the transported algae biomass to the sum of the required pumping power and the harvesting power. The results show that the increase in major losses due to increase in viscosity was overcompensated by the increase in the transported biomass energy. Also, cultivating a more concentrated slurry requires less dewatering power and is the preferred option. The largest bioenergy transport eff ectiveness was observed for the slurries with the largest initial dry biomass concentrations. Finally, the relative viscosity of algae slurries was modeled using a Kelvin-Voit based model for dilute and concentrated viscoelastic par- ticle suspensions. The model, which depends primarily on the packing factor of the algae species, agrees with the measured viscosity with an average error of 18%, while the concentrated particle suspension model was slightly more accurate than the dilute suspension model.