04 Fakultät Energie-, Verfahrens- und Biotechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/5
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Item Open Access The microalgae phaeodactylum tricornutum Is well suited as a food with positive effects on the intestinal microbiota and the generation of SCFA : results from a pre-clinical study(2022) Stiefvatter, Lena; Neumann, Ulrike; Rings, Andreas; Frick, Konstantin; Schmid-Staiger, Ulrike; Bischoff, Stephan C.Microalgae such as Phaeodactylum tricornutum (PT) are a sustainable source of nutrients, especially eicosapentaenoic acid (EPA), fucoxanthin (Fx), and chrysolaminarin (Chrl), the concentrations of which can vary depending on the culture conditions. We generated three types of diets containing either an EPA- and Fx-rich (EPA/Fx) or Chrl-rich microalgae (with 5, 15, or 25% added to the diet) or an isocaloric control diet (CD). These diets were evaluated over 14 days in young C57BL/6J mice for safety and bioavailability, short-chain fatty acid (SCFA) production, and microbiome analysis. Both microalgae diets increased body weight gain dose-dependently compared to the CD. Microalgae-derived EPA was well absorbed, resulting in increased liver and fat tissue levels and a decrease in the n-6:n-3 ratio in liver tissue. Both microalgae diets increased the production of selected SCFA and decreased the Firmicutes/Bacteriodota ratio, whereas the Chrl-rich diet led to an increase in Akkermansia. Doses of up to 4621 mg Chrl, 920 mg EPA, and 231 mg Fx per kg body weight daily were tolerated without adverse effects. This pre-clinical study shows that PT is suitable for mouse feed, with positive effects on microbiota composition and SCFA production, suggesting beneficial effects on gut health.Item Open Access Influence of light conditions on the production of chrysolaminarin using Phaeodactylum tricornutum in artificially illuminated photobioreactors(2023) Frick, Konstantin; Ebbing, Tobias; Yeh, Yen‐Cheng; Schmid‐Staiger, Ulrike; Tovar, Günter E. M.The light conditions are of utmost importance in any microalgae production process especially involving artificial illumination. This also applies to a chrysolaminarin (soluble 1,3-β-glucan) production process using the diatom Phaeodactylum tricornutum. Here we examine the influence of the amount of light per gram biomass (specific light availability) and the influence of two different biomass densities (at the same amount of light per gram biomass) on the accumulation of the storage product chrysolaminarin during nitrogen depletion in artificially illuminated flat-panel airlift photobioreactors. Besides chrysolaminarin, other compounds (fucoxanthin, fatty acids used for energy storage [C16 fatty acids], and eicosapentaenoic acid) are regarded as well. Our results show that the time course of C-allocation between chrysolaminarin and fatty acids, serving as storage compounds, is influenced by specific light availability and cell concentration. Furthermore, our findings demonstrate that with increasing specific light availability, the maximal chrysolaminarin content increases. However, this effect is limited. Beyond a certain specific light availability (here: 5 µmolphotons gDW-1 s-1) the maximal chrysolaminarin content no longer increases, but the rate of increase becomes faster. Furthermore, the conversion of light to chrysolaminarin is best at the beginning of nitrogen depletion. Additionally, our results show that a high biomass concentration has a negative effect on the maximal chrysolaminarin content, most likely due to the occurring self-shading effects.Item Open Access Monodopsis subterranea is a source of α‐tocomonoenol, and its concentration, in contrast to α‐tocopherol, is not affected by nitrogen depletion(2023) Montoya‐Arroyo, Alexander; Muñoz‐González, Alejandra; Lehnert, Katja; Frick, Konstantin; Schmid‐Staiger, Ulrike; Vetter, Walter; Frank, Janα‐Tomonoenols (αT1) are tocochromanols structurally related to tocopherols (T) and tocotrienols (T3), the bioactive members of the vitamin E family. However, limited evidence exists regarding the sources and biosynthesis of tocomonoenols. Nitrogen depletion increases the content of α‐tocopherol (αT), the main vitamin E congener, in microalgae, but little is known regarding its effect on other tocochromanols, such as tocomonoenols and tocotrienols. We therefore quantified the concentrations of T, T1, and T3, in freeze‐dried biomass from nitrogen‐sufficient, and nitrogen‐depleted Monodopsis subterranea (Eustigmatophyceae). The identities of isomers of αT1 were confirmed by LC-MS and GC-MS. αT was the predominant tocochromanol (82% of total tocochromanols). αT1 was present in higher quantities than the sum of all T3 (6% vs. 1% of total tocochromanols). 11′‐αT1 was the main αT1 isomer. Nitrogen depletion increased αT, but not αT1 or T3 in M. subterranea. In conclusion, nitrogen depletion increased the content of αT, the biologically most active form of vitamin E, in M. subterranea without affecting αT1 and T3 and could potentially be used as a strategy to enhance its nutritional value but not to increase αT1 content, indicating that αT1 accumulation is independent of that of αT in microalgae.Item Open Access Oral bioavailability of omega-3 fatty acids and carotenoids from the microalgae Phaeodactylum tricornutum in healthy young adults(2021) Stiefvatter, Lena; Lehnert, Katja; Frick, Konstantin; Montoya-Arroyo, Alexander; Frank, Jan; Vetter, Walter; Schmid-Staiger, Ulrike; Bischoff, Stephan C.The microalgae Phaeodactylum tricornutum (PT) contains valuable nutrients such as proteins, polyunsaturated omega-3 fatty acids (n-3 PUFA), particularly eicosapentaenoic acid (EPA) and some docosahexaenoic acid (DHA), carotenoids such as fucoxanthin (FX), and beta-glucans, which may confer health benefits. In a randomized intervention trial involving 22 healthy individuals, we administered for two weeks in a crossover manner the whole biomass of PT (5.3 g/day), or fish oil (FO) containing equal amounts of EPA and DHA (together 300 mg/day). In an additional experiment, sea fish at 185 g/week resulting in a similar EPA and DHA intake was administered in nine individuals. We determined the bioavailability of fatty acids and carotenoids and assessed safety parameters. The intake of PT resulted in a similar increase in the n-3 PUFA and EPA content and a decrease in the PUFA n-6:n-3 ratio in plasma. PT intake caused an uptake of FX that is metabolized to fucoxanthinol (FXOH) and amarouciaxanthin A (AxA). No relevant adverse effects occurred following PT consumption. The study shows that PT is a safe and effective source of EPA and FX—and likely other nutrients—and therefore should be considered as a future sustainable food item.Item Open Access Improving determination of pigment contents in microalgae suspension with absorption spectroscopy : light scattering effect and Bouguer-Lambert-Beer law(2023) Yeh, Yen-Cheng; Ebbing, Tobias; Frick, Konstantin; Schmid-Staiger, Ulrike; Haasdonk, Bernard; Tovar, Günter E. M.The Bouguer-Lambert-Beer (BLB) law serves as the fundamental basis for the spectrophotometric determination of pigment content in microalgae. Although it has been observed that the applicability of the BLB law is compromised by the light scattering effect in microalgae suspensions, in-depth research concerning the relationship between the light scattering effect and the accuracy of spectrophotometric pigment determination remains scarce. We hypothesized that (1) the precision of spectrophotometric pigment content determination using the BLB law would diminish with increasing nonlinearity of absorbance, and (2) employing the modified version of the BLB (mBLB) law would yield superior performance. To assess our hypotheses, we cultivated Phaeodactylum tricornutum under varying illumination conditions and nitrogen supplies in controlled indoor experiments, resulting in suspensions with diverse pigment contents. Subsequently, P. tricornutum samples were diluted into subsamples, and spectral measurements were conducted using different combinations of biomass concentrations and path lengths. This was carried out to assess the applicability of the BLB law and the nonlinearity of absorbance. The chlorophyll a and fucoxanthin contents in the samples were analyzed via high-performance liquid chromatography (HPLC) and subsequently used in our modeling. Our findings confirm our hypotheses, showing that the modified BLB law outperforms the original BLB law in terms of the normalized root mean square error (NRMSE): 6.3% for chlorophyll a and 5.8% for fucoxanthin, compared to 8.5% and 7.9%, respectively.Item Open Access Beta-glucan production of Phaeodactylum tricornutum, Monodopsis subterranea and Cylindrotheca fusiformis during nitrogen depletion(2023) Frick, Konstantin; Ebbing, Tobias; Yeh, Yen-Cheng; Schmid-Staiger, Ulrike; Tovar, Günter E. M.AbstractBeta-glucans are polysaccharides that can be used for different applications, for example as an immunomodulator in food or feed or for managing high cholesterol levels. Certain microalgae species use beta-glucans as energy storage, accumulating them during nutrient depletion. In this study, we examined and compared beta-glucan production during nitrogen depletion in three different algae species, Phaeodactylum tricornutum, Monodopsis subterranea and Cylindrotheca fusiformis, grown in artificially illuminated flat panel airlift reactors, in order to determine the most promising microalgae species for beta-glucan production. Co-products such as fatty acids (especially eicosapentaenoic acid) and the carotenoid fucoxanthin (not produced by M. subterranea) were also considered. Biomass analysis showed that P. tricornutum cultures reached a maximal beta-glucan content of 317 ± 9 mg gDW-1, M. subterranea cultures reached 188 ± 6 mg gDW-1 and C. fusiformis cultures reached 129 ± 13 mg gDW-1. Furthermore, beta-glucan production was faster in P. tricornutum cultures. However, the maximum volumetric beta-glucan concentration reached was higher in M. subterranea cultures compared to P. tricornutum cultures as M. subterranea cultures produced more biomass during nitrogen depletion. In terms of possible co-products, P. tricornutum produced fucoxanthin and EPA, whereas M. subterranea did not produce fucoxanthin. However, M. subterranea exhibited a higher EPA content, which remained above 45 mg g-1 even after several days of nitrogen depletion. Overall, our results suggest that P. tricornutum and M. subterranea are both suitable species for beta-glucan production in flat panel airlift reactors.Item Open Access Management of hypercholesterolemia through dietary ß-glucans : insights from a zebrafish model(2022) Gora, Adnan Hussain; Rehman, Saima; Kiron, Viswanath; Dias, Jorge; Fernandes, Jorge M. O.; Olsvik, Pål Asgeir; Siriyappagouder, Prabhugouda; Vatsos, Ioannis; Schmid-Staiger, Ulrike; Frick, Konstantin; Cardoso, MiguelConsumption of lipid-rich foods can increase the blood cholesterol content. β-glucans have hypocholesterolemic effect. However, subtle changes in their molecular branching can influence bioactivity. Therefore, a comparative investigation of the cholesterol-lowering potential of two β-glucans with different branching patterns and a cholesterol-lowering drug, namely simvastatin was undertaken employing the zebrafish (Danio rerio) model of diet-induced hypercholesterolemia. Fish were allocated to 5 dietary treatments; a control group, a high cholesterol group, two β-glucan groups, and a simvastatin group. We investigated plasma total cholesterol, LDL and HDL cholesterol levels, histological changes in the tissues, and explored intestinal transcriptomic changes induced by the experimental diets. Dietary cholesterol likely caused the suppression of endogenous cholesterol biosynthesis, induced dysfunction of endoplasmic reticulum and mitochondria, and altered the histomorphology of the intestine. The two β-glucans and simvastatin significantly abated the rise in plasma cholesterol levels and restored the expression of specific genes to alleviate the endoplasmic reticulum-related effects induced by the dietary cholesterol. Furthermore, the distinct patterns of transcriptomic changes in the intestine elicited by the oat and microalga β-glucans impacted processes such as fatty acid metabolism, protein catabolic processes, and nuclear division. Oat and microalgal β-glucans also altered the pattern of lipid deposition in the liver. Our study provides insights into the effectiveness of different β-glucans to alleviate dysfunctions in lipid metabolism caused by dietary cholesterol.Item Open Access Immune status and hepatic antioxidant capacity of gilthead seabream Sparus aurata juveniles fed yeast and microalga derived β-glucans(2021) Reis, Bruno; Gonçalves, Ana Teresa; Santos, Paulo; Sardinha, Manuel; Conceição, Luís E. C.; Serradeiro, Renata; Pérez-Sánchez, Jaume; Calduch-Giner, Josep; Schmid-Staiger, Ulrike; Frick, Konstantin; Dias, Jorge; Costas, BenjamínThis work aimed to evaluate the effects of dietary supplementation with β-glucans extracted from yeast (Saccharomyces cerevisiae) and microalga (Phaeodactylum tricornutum) on gene expression, oxidative stress biomarkers and plasma immune parameters in gilthead seabream (Sparus aurata) juveniles. A practical commercial diet was used as the control (CTRL), and three others based on CTRL were further supplemented with different β-glucan extracts. One was derived from S. cerevisiae (diet MG) and two different extracts of 21% and 37% P. tricornutum-derived β-glucans (defined as Phaeo21 and Phaeo37), to give a final 0.06% β-glucan dietary concentration. Quadruplicate groups of 95 gilthead seabream (initial body weight: 4.1 ± 0.1 g) were fed to satiation three times a day for 8 weeks in a pulse-feeding regimen, with experimental diets intercalated with the CTRL dietary treatment every 2 weeks. After 8 weeks of feeding, all groups showed equal growth performance and no changes were found in plasma innate immune status. Nonetheless, fish groups fed β-glucans supplemented diets showed an improved anti-oxidant status compared to those fed CTRL at both sampling points (i.e., 2 and 8 weeks). The intestinal gene expression analysis highlighted the immunomodulatory role of Phaeo37 diet after 8 weeks, inducing an immune tolerance effect in gilthead seabream intestine, and a general down-regulation of immune-related gene expression. In conclusion, the results suggest that the dietary pulse administration of a P. tricornutum 37% enriched-β-glucans extract might be used as a counter-measure in a context of gut inflammation, due to its immune-tolerant and anti-oxidative effects.Item Open Access Comparing three different Phaeodactylum tricornutum strains for the production of chrysolaminarin in flat panel airlift photobioreactors(2022) Frick, Konstantin; Yeh, Yen-Cheng; Schmid-Staiger, Ulrike; Tovar, Günter E. M.In recent years, various applications for algae-based ß-1,3-glucans have been postulated, including animal feed and human nutrition. Chrysolaminarin is a ß-1,3-1,6-glucan produced by diatoms such as Phaeodactylum tricornutum for energy storage. It is accumulated under nutrient-depleted cultivation conditions. In this study, the production of chrysolaminarin in artificially illuminated scalable flat panel airlift photobioreactors (FPA) was investigated by using P. tricornutum in a two-stage production process. In the growth stage primarily biomass is produced, and the subsequent nitrogen-depleted stage induces the accumulation of chrysolaminarin. Three P. tricornutum strains (SAG 1090-1a, SAG 1090-1b, SAG 1090-6) were cultured at laboratory scale in 6 L-FPA reactors under controlled light conditions to characterize the process and identify a production strain. The chrysolaminarin content of the algae strains was analysed and additionally their contents of eicosapentaenoic acid and fucoxanthin, both of which could be involved in a possible co-production. Strain SAG 1090-1b exhibited the highest biomass productivity and chrysolaminarin content (317 ± 9 mg gDW-1) after nitrogen depletion, and thus stood out as the most suitable for chrysolaminarin production in a two-stage process. A co-production of the three compounds is possible. However, during nitrogen depletion there occurred trade-offs between the compounds. As chrysolaminarin was produced, the amount of fucoxanthin in the culture stagnated or even decreased depending on the selected strain.