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Mixotrophic cultivation of Galdieria sulphuraria for C-phycocyanin and protein production
Journal article   Open access   Peer reviewed

Mixotrophic cultivation of Galdieria sulphuraria for C-phycocyanin and protein production

Fabian Abiusi, Pedro Moñino Fernández, Stefano Canziani, Marcel Janssen, René H. Wijffels and Maria Barbosa
Algal research (Amsterdam), Vol.61, p.102603
01/2022
DOI: 10.1016/j.algal.2021.102603
url
https://doi.org/10.1016/j.algal.2021.102603View
Published (Version of record) Open Access

Abstract

G. sulphuraria is a polyextremophilic microalga that can tolerate low pH, high temperature and high osmotic pressure. We cultivated G. sulphuraria ACUF 064 in chemostat at a biomass concentration of 134 to 243 g·m−2 aiming for maximal pigment content without compromising biomass productivity. Autotrophy was compared to ‘oxygen balanced’ mixotrophy with intracellular recirculation of oxygen and carbon dioxide. No differences were found in C-phycocyanin (C-PC) and protein content between autotrophic and mixotrophic cultures. In mixotrophy the biomass productivity and concentration were doubled compared to the photoautotrophic counterpart. In mixotrophy aeration was not needed and 89% of the substrate carbon was converted into biomass. Mixotrophically grown biomass contained 10% w/w C-PC which, combined with its high areal biomass productivity (49 g·m−2·day−1), sums up as one of the highest C-PC areal productivities ever reported (5 g·m−2·day−1) under 24 h/24 h illumination. C-PC extracted from G. sulphuraria was more stable than the currently used C-PC extracts from Spirulina. No significant loss of color was observed down to a pH of 3 and up to a temperature of 55 °C. G. sulphuraria had a protein content of 62% w/w and compared favorably with FAO dietary recommendation of adults regarding amino acid composition. G. sulphuraria contains a high proportion of essential, sulfur amino acids compared to Chlorella, Spirulina and soybean protein. Due to its attractive amino acid profile and high protein content, G. sulphuraria is a good candidate for food and feed applications to overcome sulfur amino acid deficiencies. In addition, oxygen balanced mixotrophy allows for efficient and productive cultivation of G. sulphuraria biomass. •G. sulphuraria was cultivated at biomass concentrations higher than 4 g·L−1.•G. sulphuraria had a high pigment content.•Highest ever reported C-phycocyanin areal productivity in Galdieria with light.•C-phycocyanin showed no significant loss of color down to pH 3 and up to 55 °C.•G. sulphuraria had a high protein and essential amino acid content.
Acid stable phycocyanin Amino acid profile Oxygen balance Phycocyanin productivity Protein production Thermo stable phycocyanin

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