Improvement in the Sequential Extraction of Phycobiliproteins from Arthrospira platensis Using Green Technologies.

Arthrospira platensis (commercially known as Spirulina) is an excellent source of phycobiliproteins, especially C-phycocyanin. Phycobiliproteins are significant bioactive compounds with useful biological applications. The extraction process plays a significant role in downstream microalga production and utilisation. The important pigments found in A. platensis include chlorophyll and carotenoids as nonpolar pigments and phycobiliproteins as polar pigments. Supercritical fluid extraction (SFE) as a green extraction technology for the high-value metabolites of microalgae has potential for trends in food and human health. The nonpolar bioactive compounds, chlorophyll and carotenoids of A. platensis, were primarily separated using supercritical carbon dioxide (SC-CO2) solvent-free fluid extraction pressure; the temperature and ethanol as cosolvent conditions were compared. The residue from the A. platensis cells was subjected to phycobiliprotein extraction. The phosphate and water extraction of A. platensis SFE residue were compared to evaluate phycobiliprotein extraction. The SFE results exhibited higher pressure (350 bar) and temperature extraction (50 °C) with ethanol-free extraction and increased nonpolar pigment. Phycobiliprotein yield was obtained from A. platensis SFE residue by ethanol-free buffer extraction as a suitable process with antioxidant properties. The C-phycocyanin was isolated and enhanced to 0.7 purity as food grade. This developed method can be used as a guideline and applied as a sustainable process for important pigment extraction from Arthrospira microalgae.

Arthrospira platensis Mutagenesis for Protein and C-Phycocyanin Improvement and Proteomics Approaches.

Arthrospira (Spirulina) platensis is known for its use as a food supplement, with reported therapeutic properties including antiviral, anti-inflammatory and antioxidant activity. Arthrospira is also an excellent source of proteins and C-phycocyanin. The latter is a light-harvesting pigment-protein complex in cyanobacteria, located on the outer surface of the thylakoid membrane and comprising 40 to 60% of the total soluble protein in cells. Random mutagenesis is a useful tool as a non-genetically modified mutation method that has been widely used to generate mutants of different microorganisms. Exposure of microalgae or cyanobacteria to chemical stimuli affects their growth and many biological processes. Chemicals influence several proteins, including those involved in carbohydrate and energy metabolisms, photosynthesis and stress-related proteins (oxidative stress-reactive oxygen species (ROS) scavenging enzymes). Signal transduction pathways and ion transportation mechanisms are also impacted by chemical treatment, with changes causing the production of numerous biomolecules and stimulation of defence responses. This study compared the protein contents of A. platensis control and after mutagenesis using diethyl sulphate (DES) under various treatment concentrations for effective mutation of A. platensis. Results identified 1152 peptides using proteomics approaches. The proteins were classified into 23 functional categories. Random mutagenesis of A. platensis by DES was found to be highly effective for C-phycocyanin and protein production.