Repeated fed-batch cultivation of Arthrospira (Spirulina) platensis using urea as nitrogen source

Arthrospira (Spirulina) platensis (Nordstedt) Gomont was autotrophically cultivated for biomass production in repeated fed-batch process using urea as nitrogen source, with the aim of making large-scale production easier, increasing cell productivity and then reducing the production costs. It was investigated the influence of the ratio of renewed volume to total volume (R), the urea feeding time (tf) and the number of successive repeated fed-batch cycles on the maximum cell concentration (Xm), cell productivity (Px), nitrogen-to-cell conversion yield (Yx/n), maximum specific growth rate (μm) and protein content of dry biomass. The experimental results demonstrated that R = 0.80 and tf = 6 d were the best cultivation conditions, being able to simultaneously ensure, throughout the three fed-batch cycles, the highest average values of three of the five responses (Xm = 2101 ± 113 mg L−1, Px = 219 ± 13 mg L−1 d−1 and Yx/n = 10.3 ± 0.8 g g−1).