Semi-continuous immobilized cultivation of Porphyridium cruentum for sulfated polysaccharides production

[Display omitted] •The immobilization with Ca-alginate bead (CAB) was applied for Porphyridium culture.•CAB can be used for the semi-continuous cultivation of P. cruentum.•CAB promotes P. cruentum growth (168%) and SPs production (145%).•CAB can be co-applied with the different light wavelengths and nutrient deficiency.•Co-application of CAB and blue light increases the phycobiliproteins content (361%). In this study, semi-continuous immobilized cultivation of Porphyridium cruentum through calcium alginate beads was performed for sulfated polysaccharides (SPs) production. The cell biomass and daily SPs productivity in the calcium alginate bead immobilized culture were increased by up to 79 ± 3.4% and 45.6 ± 3.2%, compared to those in the control, respectively. Furthermore, simultaneous application of immobilization and blue wavelength illumination further increased the phycobiliproteins content by 260 ± 9%, compared to those in the control. Similarly, nutrient deficiencies in combination with immobilization increased daily SPs productivity by about twice that of the control. The chemical composition and biological activity of the extracellular polymeric substances produced through immobilization were similar to those of the control. This study suggests the potential application of calcium alginate beads-based immobilization for continuous and high-efficiency SPs production using P. cruentum.