Effects of Agitation and Aeration on Growth Kinetics of Spirulina platensis and Production of Natural Pigments in Stirred Photobioreactor

Spirulina platensis is a planktonic, photosynthetic filamentous cyanobacterium with bioactive molecules, which is a rich source of pigments such as phycocyanin.In this study, effects of two important factors of agitation and aeration on biomass production of S. platensis and its production of chlorophyll, phycocyanin, allofycocyanin and carotenoids at 28 °C, pH 9 and with agitation rates of 20 and 50 rpm with and without aeration were studied in immersion culture using stirring reactor. Results showed that aeration in treatments with agitation rates of 20 rpm significantly increased concentrations of the pigments (phycocyanin, allofycocyanin, chlorophyll and carotenoids) and biomass. In contrast, aeration in treatments with agitation rates of 50 rpm inhibited pigment production (P<0.05). The highest quantity of biomass and concentrations of phycocyanin, allofycocyanin, chlorophyll and carotenoids respectively were 1.39 g.l-1 and 136.5, 38, 8.62 and 3.05 mg.l-1, which were linked to treatment with aerationat 20 rpm. Based on the current results, aeration of the culture media significantly increased concentrations of allofycocyanin. Under conditions without aeration, increases in agitation rates increased biomass quantities. The highest quantity of biomass and concentrations of phycocyanin, allofycocyanin, chlorophyll and carotenoids were achieved using aeration at an agitation speed of 20 rpm.