Enhanced production of poly-3-hydroxybutyrate and carotenoids by Arthrospira platensis under combined glycerol and phosphorus supplementation

Arthrospira platensis is one of the most beneficial cyanobacteria due to its high protein content and high-value compounds such as poly-3-hydroxybutyrate (PHB) and carotenoids which can be used in promoting health in many sectors. A. platensis cultivation can be performed using urban or industrial wastewater as a source of nutrients, including glycerol and phosphorus. The objective of this study was to enhance biomass, pigments, and partial PHB in A. platensis IFRPD1182 grown under different glycerol and phosphorus concentrations. The highest values of biomass, carotenoids, and PHB production were observed in cells grown in the G(3)P(3) medium supplemented with 4.6 g/l glycerol and 356 mg/l phosphorus on the fifth day of cultivation with maximal values of 1.90 +/- 0.03 mg/ml, 6.30 +/- 0.12 mg/l, and 34.76 +/- 2.71 mg/l, respectively. In addition, RT-PCR analysis revealed that the cells grown in G(3)P(3) medium increased crtB and crtP transcripts, encoding phytoene synthase and phytoene desaturase, respectively, and involved in carotenoid biosynthesis with 1.47- and 1.50-fold increases, respectively. This indicates that the increased expression of crtB and crtP genes in the cells can be achieved by a combination of glycerol and phosphorus, where the carotenoids were highly accumulated.