Formulating of cost-effective media for Spirulina Cultivation

Zarrouk’s medium (ZM) is a standard medium for Spirulina cultivation. Nevertheless, reliance on imported fertilizers greatly increases production costs. Therefore, this study aimed to develop a cost-effective medium by either reducing fertilizer consumption or exploring alternative sources for Spirulina cultivation. Arthrospira (Spirulina) platensis was cultivated in a modified ZM and compared to the standard medium. The modified media were categorized into two groups: seawater-based modified media with different concentrations of seawater (5%, 10%, 15%, and 20%), supplemented with either standard (16.8 g L^-1) or low (4 g L^-1) amounts of NaHCO₃ and carbon (C)- and nitrogen (N)-based modified media, featuring reduced carbon (8 g L^-1 NaHCO₃) along with low-nitrogen sources (0.85 g L^-1 NaNO₃ or 0.3 g L^-1 urea). The results showed that producing spirulina using seawater-based modified media with 4 g L^-1 NaHCO₃ achieved a reduction in cost up to 40% compared to ZM. In addition, reducing C- and N-based modified media (using NaNO₃ or urea) exhibited a cost reduction exceeding 50% of ZM. Among the modified culture media, Spirulina cultivated in the modified medium containing 8 g L^-1 NaHCO₃ and 0.85 g L^-1 NaNO₃ showed comparable biochemical contents to those cultivated in the ZM. Consequently, this modified medium was further employed for Spirulina outdoor cultivation, using working volumes of 600 and 3,000 liters. Impressively, the biomass yield and biochemical content achieved were on par with those obtained from ZM. The results obtained suggest that the modified medium has the potential to notably reduce the medium cost in large-scale production.