Rapid and accurate determination of protein content in North Atlantic seaweed by NIR and FTIR spectroscopies

Seaweed is considered a potentially sustainable source of protein for human consumption, and rapid, accurate methods for determining seaweed protein contents are needed. Seaweeds contain substances which interfere with common protein estimation methods however. The present study compares the Lowry and BCA protein assays and protein determination by N-ratios to more novel spectroscopic methods. Linear regression of the height or the integrated area under the Amide II band of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to predict seaweed protein with good prediction performance. Partial least squares regression (PLSR) was performed on both DRIFTS and near-infrared (NIR) spectra, with even higher prediction accuracy. Spectroscopy performed similar to or better than the calculated N-ratio of 4.14 for protein prediction. These spectral prediction methods require minimal sample preparation and chemical use, and are easy to perform, making them environmentally sustainable and economically viable for rapid estimation of seaweed protein.Rapid and accurate determination of protein content in North Atlantic seaweed by NIR and FTIR spectroscopiespublishedVersio

High-value compound induction by flashing light in Diacronema lutheri and Tetraselmis striata CTP4

Phototrophic microalgae use light to produce biomass and high-value compounds, such as pigments and polyunsaturated fatty acids (PUFA), for food and feed. These biomolecules can be induced by flashing light during the final growth stage. We tested different exposure times (1–6 days) of flashing light (f = 0.5, 5, 50 Hz; duty cycle = 0.05) on biomass, pigment and fatty acid productivity in Diacronema lutheri and Tetraselmis striata. A three-day exposure to low-frequency (5 Hz) flashing light successfully increased the production of fucoxanthin, diatoxanthin, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in D. lutheri up to 4.6-fold and of lutein, zeaxanthin and EPA in T. striata up to 1.3-fold compared to that of continuous light. Biomass productivity declined 2-fold for D. lutheri and remained similar for T. striata compared to that of continuous light. Thus, short-term treatments of flashing light may be promising for industrial algal production to increase biomass value.publishedVersio

Divergent Responses in Growth and Nutritional Quality of Coastal Macroalgae to the Combination of Increased pCO\u3csub\u3e2\u3c/sub\u3e and Nutrients

Coastal ecosystems are subjected to global and local environmental stressors, including increased atmospheric carbon dioxide (CO2) (and subsequent ocean acidification) and nutrient loading. Here, we tested how two common macroalgal species in the Northwest Atlantic (Ulva spp. and Fucus vesiculosus Linneaus) respond to the combination of increased CO2 and nutrient loading. We utilized two levels of pCO2 with two levels of nutrients in a full factorial design, testing the growth rates and tissue quality of Ulva and Fucus grown for 21 days in monoculture and biculture. We found that the opportunistic, fast-growing Ulva exhibited increased growth rates under high pCO2 and high nutrients, with growth rates increasing three-fold above Ulva grown in ambient pCO2 and ambient nutrients. By contrast, Fucus growth rates were not impacted by either environmental factor. Both species exhibited a decline in carbon to nitrogen ratios (C:N) with elevated nutrients, but pCO2 concentration did not alter tissue quality in either species. Species grown in biculture exhibited similar growth rates to those in monoculture conditions, but Fucus C:N increased significantly when grown with Ulva, indicating an effect of the presence of Ulva on Fucus. Our results suggest that the combination of ocean acidification and nutrients will enhance abundance of opportunistic algal species in coastal systems and will likely drive macroalgal community shifts, based on species-specific responses to future conditions

Inorganic carbon physiology underpins macroalgal responses to elevated CO2

Beneficial effects of CO2 on photosynthetic organisms will be a key driver of ecosystem change under ocean acidification. Predicting the responses of macroalgal species to ocean acidification is complex, but we demonstrate that the response of assemblages to elevated CO2 are correlated with inorganic carbon physiology. We assessed abundance patterns and a proxy for CO2:HCO3- use (\u3b413C values) of macroalgae along a gradient of CO2 at a volcanic seep, and examined how shifts in species abundance at other Mediterranean seeps are related to macroalgal inorganic carbon physiology. Five macroalgal species capable of using both HCO3- and CO2 had greater CO2 use as concentrations increased. These species (and one unable to use HCO3-) increased in abundance with elevated CO2 whereas obligate calcifying species, and non-calcareous macroalgae whose CO2 use did not increase consistently with concentration, declined in abundance. Physiological groupings provide a mechanistic understanding that will aid us in determining which species will benefit from ocean acidification and why