Potential of the marine diatom Halamphora coffeaeformis to simultaneously produce omega-3 fatty acids, chrysolaminarin and fucoxanthin in a raceway pond

Omega-3 eicosapentaenoic fatty acid (C20:5; EPA), β-glucan and fucoxanthin have received widespread attention owing to their potential industrial applications; however, their availability is currently limited to unsustainable sources such as fish oils and macroalgae. Though some species of diatoms are also a natural source of these metabolites, progress needs to be made in reducing the cost barriers involved in their large-scale production. The aim of the present study was therefore to assess the potential of the marine diatom Halamphora coffeaeformis to simultaneously accumulate EPA, chrysolaminarin and fucoxanthin in a raceway pond sustained by fertilizer (Bayfolan®)-enriched seawater. The biomass production increased significantly along the experiment, the specific growth rate, biomass productivity and areal yield being 2.03 day−1, 0.128 g.L−1.d−1 and 25.73 g.m−2.d−1, respectively. Proteins dominated in the first culture phase, while lipids, carbohydrates and pigments increased toward the end of the stationary phase. The harvested biomass presented 310 mg.g−1 DW (dry weight) of total lipids containing high amounts of EPA (24% of total fatty acids), 114 mg.g−1 DW of chrysolaminarin and 38 mg.g−1 DW of fucoxanthin. These values compare favorably with those obtained from commercially used sources. The culture medium proposed represents a non-conventional, cost-effective resource allowing for sustained high biomass levels throughout 22 days, guaranteeing the accumulation of valuable metabolites. Furthermore, the robustness and auto-flocculation capacity of the species increase the chances of viable scalability. These findings indicate the potential of H.coffeaeformis as a high-value metabolite feedstock, focusing on sustainable bioprocesses

Simultaneous production assessment of triacylglycerols for biodiesel and exopolysaccharides as valuable co-products in Navicula cincta

The marine benthic diatom Navicula cincta was cultured in order to evaluate its capacity to produce both neutral lipid-triacylglycerols (TAG) for biodiesel, and exopolysaccharides (EPS), as valuable co-products, under the same environmental conditions. The species was cultured without applying stress conditions, except for the ones naturally created by the culture age. Peaks of neutral lipid accumulation were estimated by fluorimetry by Nile Red. Consequently, lipids were extracted and fractionated into neutral and polar fractions and the fatty acid profile of each fraction analysed by GC. The stationary phase began on day 6, when phosphate and silicate reached limiting values for diatom growth. Total lipids and lipid fractions did not show differences between harvesting time points, reaching total lipid up to 41% of ash-free dry weight (AFDW) and TAG the dominant fraction (ca. 90% of total lipids). Particularly noticeable was the storage of palmitoleic acid (ca. 54% of total fatty acid methyl esters) and a lower level of polyunsaturated fatty acids, which may impart overall favourable properties to a biodiesel fuel, especially cold flow and oxidative stability. The maximum concentrations of EPS corresponded to soluble fraction, which was most significant when the cultures reached the stationary phase and when the medium was almost phosphate and silicate depleted. The characterization of soluble EPS indicated the presence of N-glycopeptides. According to the present results, a hypothetical scheme of demonstrative cultures under a biorefinery approach is proposed for N. cincta.Fil: Barnech Bielsa, Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Popovich, Cecilia Angelines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Rodriguez, María C.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Martinez, Ana María. Universidad Nacional del Sur. Departamento de Química; ArgentinaFil: Martin, Lucas Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Matulewicz, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Leonardi, Patricia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentin