Evaluation of unconventional fertilizer-based media for enhanced biomass and metabolite productivity in Scenedesmus dimorphus

Microalgae offer many advantages, such as rapid growth rates, high adaptability to diverse environmental conditions, and superior carbon dioxide fixation compared to terrestrial plants. However, the high production costs hinder their large-scale industrial application. As such, researchers are exploring ways to reduce costs and enhance productivity. In this context, the aim of this study was to evaluate the effects of two unconventional culture media, formulated with Bayfolan fertilizer, on biomass and metabolite productivity of Scenedesmus dimorphus. The two media tested included 1 mL of fertilizer per liter (BM) and BM supplemented with 250 mg NaNO₃/L (EBM), which were compared to the standard Basal Medium of Bold (BBM). Scenedesmus dimorphus was cultivated in 2000 L raceways under greenhouse conditions in a semicontinuous culture system over three cycles. The highest biomass productivity was observed in EBM, at 14.59 ± 3.55 g/m²·d, which was significantly higher than BM (7.82 ± 4.55 g/m²·d) and comparable to BBM. In terms of metabolite productivity, significant differences were observed, with carbohydrates being the predominant metabolites produced under all media conditions. While no significant differences were found in metabolite production between the unconventional media and BBM, the costs of EBM and BM were 74.5% and 36.8% lower, respectively, compared to BBM. These findings suggest that the use of Bayfolan-based media could be a cost-effective alternative for large-scale microalgal cultivation. Future studies should explore the long-term effects of such media on different species and investigate the scalability of these findings for industrial applications.