Cost-effective culture media for biomass production of spirulina using betel fertilizer

Abstract

Spirulina (Arthrospira platensis) is a nutrient-rich blue-green cyanobacterium extensively cultivated for sustainable food production, pharmaceuticals, and industrial applications. However, the high cost of conventional growth media poses a challenge to largescale production. Traditionally, Spirulina is cultured in Zarrouk’s medium (ZM), which provides optimal nutrients but is expensive for large-scale cultivation. The study aimed to identify a cost-effective alternative to ZM by incorporating betel fertilizer (BF), a readily available and inexpensive nutrient source. Five culture media formulations were tested: 100% ZM, 75% ZM +25% BF, 50% ZM + 50% BF, 25% ZM + 75% BF and 100% BF, each with three replicates. Growth performance, biomass yield, pigment content, cell productivity, maximum specific growth rate, cell doubling time and economic viability were assessed over a 16-day cultivation period. Cultures were maintained under a continuous illumination (35W fluorescent tubes, 300–500lux) and continuous aeration. Results revealed that up to 50% of ZM can be replaced with BF without significantly affecting growth rate, biomass yield, cell concentration, maximum specific growth rate or cell productivity. Statistical analysis using one-way ANOVA (p > 0.05) showed that the 50% mixture performed similarly to the 100% ZM treatment in these parameters, while reducing production cost. Furthermore, Duncan’s multiple range test confirmed that the mean values across these treatments were not significantly different. Pigment content analysis also showed no statistically significant decline (p > 0.05) up to the 50% mixture compared to 100% ZM, indicating that BF substitution did not compromise biochemical composition. These findings demonstrate that replacing 50% of ZM with BF preserves Spirulina growth efficiency while significantly lowering production costs, presenting a promising alternative for commercial cultivation.