Using a trait-based approach to optimize mixotrophic growth of the red microalga Porphyridium purpureum towards fatty acid production

Abstract

BackgroundOrganic carbon sources have been reported to simultaneously increase the growth and lipid accumulation in microalgae. However, there have been no studies of the mixotrophic growth of Porphyridium purpureum in organic carbon media. In this study, three organic carbon sources, glucose, sodium acetate, and glycerol were used as substrates for the mixotrophic growth of P. purpureum. Moreover, a novel trait-based approach combined with Generalized Additive Modeling was conducted to determine the dosage of each organic carbon source that optimized the concentration of cell biomass or fatty acid.ResultsA 0.50% (w/v) dosage of glucose was optimum for the enhancement of the cell growth of P. purpureum, whereas sodium acetate performed well in enhancing cell growth, arachidonic acid (ARA) and eicosapentaenoic acid (EPA) content, and glycerol was characterized by its best performance in promoting both cell growth and ARA/EPA ratio. The optimum dosages of sodium acetate and glycerol for the ARA concentration were 0.25% (w/v) and 0.38% (v/v), respectively. An ARA concentration of 211.47 mg L−1 was obtained at the optimum dosage of glycerol, which is the highest ever reported.ConclusionsThe results suggested that a comprehensive consider of several traits offers an effective strategy to select an optimum dosage for economic and safe microalgae cultivation. This study represents the first attempt of mixotrophic growth of P. purpureum and proved that both biomass and ARA accumulation could be enhanced under supplements of organic carbon sources, which brightens the commercial cultivation of microalgae for ARA production.

Maximizing Polysaccharides and Phycoerythrin in Porphyridium purpureum via the Addition of Exogenous Compounds: A Response-Surface-Methodology Approach

“…The MG concentration was negatively correlated with the biomass of P. purpureum , with the highest biomass occurring at a low MG concentration (8 g L −1 ). This result agreed with a previous report that the biomass of P. purpureum was 1.82 times higher at a glucose concentration of 5 g L −1 compared to a concentration of 10 g L −1 [ 22 ]. It was also reported that the biomass yields of C. vulgaris and S. obliquus peaked when the magnesium concentration increased to double that of the control [ 26 ].…”

“…To date, much research has been conducted regarding how to enhance the concentrations of phycoerythrin and polysaccharides in P. purpureum to better meet market demands. The main strategies have focused on improving the culture media [ 1 ], supplying exogenous substances [ 20 ], optimizing environmental factors [ 21 ], and changing the culture method [ 22 ]. The optimization of the culture medium is a primary method for enhancing microalgal growth and increasing the production of bioactive substances.…”

“…Additionally, the presence of an organic carbon source can influence the yields of biomass and bioactive substances in P. purpureum [ 23 ]. For instance, the maximum biomass of P. purpureum CoE1 was achieved with a 0.5% ( w / v ) glucose dosage, while the maximum arachidonic acid (ARA) concentration was obtained with a 0.38% ( w / v ) glycerol dosage [ 22 ]. Furthermore, adding exogenous substances is essential for maximizing microalgal biomass and the concentrations of bioactive substances.…”

Cultivation of a Novel Strain of Chlorella vulgaris S2 under Phototrophic, Mixotrophic, and Heterotrophic Conditions, and Effects on Biomass Growth and Composition

“…However, growth on organic carbon is limited to a few microalgae strains belonging to the major classes, including Chlorophyceae (green microalgae; Chlorella vulgaris, Chlorella zofigiensis, Chlamydomons sp., Dunaliella salina, Nannochloropsis gaditana, and Botryococcus braunii), Bacillariophyceae (including diatoms; Phaeodactylum tricornutum, Skeletonema costatum, Navicula saprophila, and Nitzschia sp. ), and Porphyridiophyceae (red microalgae; Porphyridium purpureum) [10][11][12].…”

Screening and Identification of Coastal Chilean Thraustochytrids for Arachidonic Acid Production: Biotechnological Potential of Ulkenia visurgensis Lng2-Strain

“…Other candidates are autotrophic microalgae. Parietochloris incisa and Porphyridium purpureum stand out, the latter, red unicellular microalgae, under stress conditions (of light intensity, pH, temperature, salinity, and nutrient deficiency) can reach 40% ARA of total fatty acids [ 33 , 34 ]. However, its large-scale commercialization is limited by its autotrophic metabolism, which implies low accessibility of cells to light when there is high cell density, evaporation problems, and the use of large extensions of land for its cultivation [ 35 , 36 ].…”