Carotenoid Production from Microalgae: The Portuguese Scenario.

Microalgae have an outstanding capacity to efficiently produce value-added compounds. They have been inspiring researchers worldwide to develop a blue biorefinery, supporting the development of the bioeconomy, tackling the environmental crisis, and mitigating the depletion of natural resources. In this review, the characteristics of the carotenoids produced by microalgae are presented and the downstream processes developed to recover and purify them are analyzed, considering their main applications. The ongoing activities and initiatives taking place in Portugal regarding not only research, but also industrialization under the blue biorefinery concept are also discussed. The situation reported here shows that new techniques must be developed to make microalgae production more competitive. Downstream pigment purification technologies must be developed as they may have a considerable impact on the economic viability of the process. Government incentives are needed to encourage a constructive interaction between academics and businesses in order to develop a biorefinery that focuses on high-grade chemicals.

Extraction and purification of phycobiliproteins from algae and their applications.

Microalgae, macroalgae and cyanobacteria are photosynthetic microorganisms, prokaryotic or eukaryotic, living in saline or freshwater environments. These have been recognized as valuable carbon sources, able to be used for food, feed, chemicals, and biopharmaceuticals. From the range of valuable compounds produced by these cells, some of the most interesting are the pigments, including chlorophylls, carotenoids, and phycobiliproteins. Phycobiliproteins are photosynthetic light-harvesting and water-soluble proteins. In this work, the downstream processes being applied to recover fluorescent proteins from marine and freshwater biomass are reviewed. The various types of biomasses, namely macroalgae, microalgae, and cyanobacteria, are highlighted and the solvents and techniques applied in the extraction and purification of the fluorescent proteins, as well as their main applications while being fluorescent/luminescent are discussed. In the end, a critical perspective on how the phycobiliproteins business may benefit from the development of cost-effective downstream processes and their integration with the final application demands, namely regarding their stability, will be provided.

Recovery of bacterioruberin and proteins using aqueous solutions of surface-active compounds.

Haloarchaea microorganisms are little explored marine resources that can be a promising source of valuable compounds with unique characteristics, due to their adaptation to extreme environments. In this work, the extraction of bacterioruberin and proteins from Haloferax mediterranei ATCC 33500 was investigated using aqueous solutions of ionic liquids and surfactants, which were further compared with ethanol. Despite the good performance of ethanol in the extraction of bacterioruberin, the use of aqueous solutions of surface-active compounds allowed the simultaneous release of bacterioruberin and proteins in a multi-product process, with the non-ionic surfactants being identified as the most promising. The optimum operational conditions allowed a maximum extraction yield of 0.37 ± 0.01 mgbacterioruberin gwet biomass -1 and 352 ± 9 mgprotein gwet biomass -1 with an aqueous solution of Tween® 20 (at 182.4 mM) as the extraction solvent. In addition, high purities of bacterioruberin were obtained, after performing a simple induced precipitation using ethanol as an antisolvent to recover the proteins present in the initial extract. Finally, a step for polishing the bacterioruberin was performed, to enable solvent recycling, further closing the process to maximize its circularity.

Temperature-responsive extraction of violacein using a tuneable anionic surfactant-based system.

A tuneable thermoresponsive system based on combinations of sodium dodecyl sulfate surfactant with tetrabutylammonium chloride salt is presented as an integrated process for the solid-liquid extraction of violacein from bio-engineered Yarrowia lipolytica yeast and its purification by cloud-point separation from contaminant proteins.