From Laboratory to Production: Innovating the Small-scale Mass Production of Spirulina (Arthrospira platensis) with an Alternative Culture Medium and Refined Culture Conditions

This study reports information on the small-scale mass production of spirulina utilizing low cost and locally available media under refined culture conditions in northern Mindanao, Philippines. A low-cost alternative culture medium was formulated using NPK 30-10-10 fertilizer as the main nutrient source, after which the optimum nutrient levels were first determined, followed by refinement of the culture conditions (i.e., salinity, aeration intensity, photoperiod, inoculum density, and inoculum growth phase). Furthermore, the proximate composition of the product, spirulina powder, was determined, and a cost-return analysis was performed. The optimum level for the NPK 30-10-10 fertilizer was found to be 1.0 mM N, which resulted in the highest biomass production of 0.750 ± 0.06 g L⁻¹. The highest biomass and best growth indices were observed at 30 ppt salinity, 90 L h⁻¹ aeration intensity, 24:0 L:D photoperiod, and 1.5 g L⁻¹ inoculum density in the exponential phase. The spirulina powder produced was of good quality based on its proximate composition, with 62.87 ± 1.38% crude protein, 6.62 ± 0.05% minerals, 0.38 ± 0.01% crude fat, 3.91 ± 0.47% crude fiber, 14.84 ± 1.76% carbohydrate, 11.38 ± 0.02% moisture, and 314.24 ± 2.04 kcal 100 g⁻¹ total digestible energy. The cost-return analysis showed that small-scale production is profitable, with a 65.22% return on investment and a payback period of 1.82 years. This small-scale production technology of spirulina can be adapted by local companies and cooperatives to spur local spirulina production in the country.