Production and nutritive value of Spirulina platensis in reduced cost media

This study aimed to provide a cost effective medium to large scale production of Spirulina platensis. This intention was implemented by substituting all the nutrients present in Zarrouk’s medium (SM) with cheaper and locally available commercial fertilizers and chemicals. The Reduced Cost medium contained single super phosphate (SSP), commercial sodium bicarbonate, Muriate of potash (MOP) and crude sea-salt, (Syahat salt). Four grades of nitrogen concentrations representing 10%, 20%, 30% and 40% of SM nitrogen concentration (29.42 mM-N) were taken from ammonium nitrate (Treatments 1–4) or urea (Treatments 5–8) respectively, for testing. The alga was grown for 33 days at 30 ± 2 °C, pH 9, 30 μEm2 s−1 irradiance. The growth characteristics (maximum biomass Xm, cell productivity Px, specific growth rate μm and chlorophyll concentration), and biochemical composition (proteins, carbohydrates and lipids) of the alga grown in these media were compared with that cultivated in SM. Significant differences in the growth parameters and biochemical composition were observed for the different nitrogen sources and concentrations. The results revealed that S. platensis could utilize ammonium nitrate most efficiently and that growth was enhanced with increasing the concentrations of ammonium nitrate giving maximum biomass at 0.353 g/L (Treatment 3). Further increasing the concentration limited growth. The growth parameters in urea showed a significant decrease associated with increasing urea concentrations. The maximum biomass, chlorophyll and protein yield (0.813 ± 0.018 mg/L, 0.0685 ± 0.0024 μg/L and 52.62%, respectively) were recorded using Treatment 3 which was comparable with that of SM (0.840 ± 0.008 mg/L, 0.0701 ± 0.0089 μg/L and 52.95%, respectively). The results indicated that the newly prepared medium can be used profitably for large-scale mass production of protein-rich Spirulina and yields similar performance with cost effective to Zarrouk’s medium.