Effects of geographical location on potentially valuable components in Ulva intestinalis sampled along the Swedish coast

Abstract

Macroalgal biomass has the potential to become an important source of chemicals and commodities in a future biorefinery. Currently, production of macroalgal biomass is expensive and the content of high-value compounds is often low. Therefore, in this study the biochemical composition of Ulva intestinalis along the Swedish west coast and the east coast up to Stockholm was assessed with the aim of determining how the content of potentially valuable compounds, such as rhamnose, iduronic acid and PUFAs, could be maximized by utilizing natural variation in the choice of marine cultivation site. Along the investigated coastline, the salinity dropped from 19.4‰ at high latitudes along the west coast to 5.4‰ at Stockholm. Nitrogen and phosphorus availability varied, while temperature was similar at all locations. The two major components of biomass, carbohydrates and ash, varied inversely with the highest content of ash in the west and carbohydrates in the east. In addition, total fatty acids were significantly higher in west coast samples at 3.2 g 100 g-1 dw, with a higher proportion of mono-and polyunsaturated fatty acids. Some healthbeneficial fatty acids were found, including EPA and DPA, at 10-50 mg 100 g-1 dw, respectively. The metal content and elemental composition varied widely, probably due to the influence of specific local conditions. The P content was correlated with the phosphorus concentration in waters at the locations. In PCA analysis, the monosaccharides constituting the cell wall polysaccharide ulvan were found to vary by geographical location, with higher levels possibly associated with lower salinities. However, only glucuronic acid differed significantly between sites. These results show the considerable geographical variability in the composition of Swedish U. intestinalis and suggest that different salinities could be used to create a lipid-or carbohydrate-rich biomass.

Sustainable Large-Scale Aquaculture of the Northern Hemisphere Sea Lettuce, Ulva fenestrata, in an Off-Shore Seafarm

“…Our data on total carbohydrates (25.95-29.69% dw) were distributed in the lower to middle range of what has previously been reported for Ulva spp. (15-65% dw) [27,36,37,68]. Notably, our data showed a tendency of increased carbohydrates when lower temperatures and low densities were applied during the hatchery phase.…”

“…Furthermore, higher values of total rhamnose (11.74-17.39% dw) and iduronic acid (1.77-3.51% dw) contents have been found in Swedish wild-collected Ulva spp. during the summer months [36]. To conclude, if aiming for an increase of the total carbohydrate content and to especially enrich the high value bioactive compounds of rhamnose and iduronic acid in off-shore cultivated biomass of U. fenestrata, a harvest of the biomass during summer when water temperature and irradiance are significantly higher than during the harvest period (April) of the present study should be considered.…”

“…Additionally, value-added products such as functional foods, cosmeceuticals, nutraceuticals and pharmaceuticals can be produced from their many bioactive compounds [34,35]. Ulva biomass can exhibit high total carbohydrate contents (15-65% dw) [27,36,37] and comprises the soluble sulphated polysaccharide ulvan. Ulvan can be used in water-conditioning hydrogels [11] and can be processed into heparin-like oligosaccharides as well as into rare monosaccharides, such as rhamnose and iduronic acid [10].…”

“…Ulvan can be used in water-conditioning hydrogels [11] and can be processed into heparin-like oligosaccharides as well as into rare monosaccharides, such as rhamnose and iduronic acid [10]. Recent studies have shown that environmental growth conditions have significant effects on the relative growth rate as well as on the biochemical composition of the abovenamed high-value compounds, e.g., [36][37][38][39][40] which underlines the importance of the optimization of cultivation conditions in aquaculture settings [40].…”

Effect of Geographical Location on the Variation in Products Formed from the Hydrothermal Liquefaction of Ulva intestinalis

“…Samples were diluted and kept at 4 °C, and analysis was performed in triplicate within approximately 48 h. Highperformance anion-exchange chromatography with pulsed amperometric detection (HPAEC−PAD) was used for detection as described previously, 47 with minor modifications, incorporating a gradient of increasing sodium acetate content to separate sugar acids. 49 The total carbohydrate content was calculated as the sum of all monosaccharides and sugar acids, with correction for the addition of water during hydrolysis of polysaccharides. The crude oil protein content was calculated from the biomass nitrogen content using a conversion factor of 5 as established previously.…”