Optimization of cultivation mode for pilot-scale biomass and B-phycoerythrin production by red microalgae Porphyridium purpureum in different seasons
摘要
Development of sustainable technologies for production of the red microalga Porphyridium purpureum is an important objective to reduce the production costs and expand its incorporation into food, feed, and nutraceutical products. The aim of this study was to evaluate the production potential of P. purpureum under different cultivation modes and to optimize its pilot–scale cultivation in open ponds under mid-latitude climate conditions (spring–summer and autumn). Batch and semicontinuous photoautotrophic cultivation, as well as batch mixotrophic cultivation (with glycerol), were compared in terms of biomass and B–phycoerythrin (B–PE) productivity. The highest biomass productivity (22.3 g m–2 day–1) was obtained under mixotrophic cultivation in summer, which was 2–3 times higher than in photoautotrophic modes. However, mixotrophic growth markedly reduced the B–PE content in the biomass (down to 2.85% vs. 6–7% under photoautotrophic conditions). In photoautotrophic batch and semicontinuous cultures, the areal biomass productivity reached 10.5 and 13.8 g m–2 day–1, respectively, with B–PE productivity up to 0.71 g m–2 day–1. A strong correlation was found between productivity and the daily solar energy input; the optimal daily irradiance was ≥ 5 MJ m–2 day–1. The associated bacterial biomass remained below 0.014% of the total biomass and did not significantly affect culture performance.
We conclude that photoautotrophic batch and semicontinuous cultivation are preferable for producing B–PE–rich biomass, whereas mixotrophic cultivation is advantageous for rapid biomass accumulation but not for pigment synthesis. Greenhouse pond systems provide a feasible and scalable platform for industrial cultivation of P. purpureum.