Modified culture media development using locally available fertilizers and vitamin supplements for continuous mass culture of Chaetoceros gracilis

Abstract

Microalgae culture is a vital nutritional resource for hatchery development in aquaculture and has gained significant interest as a sustainable food ingredient, versatile feedstock for biofuels, with broad industrial applications. The high cost of microalgae culture media hinders mass production, necessitating the development of affordable, simpler alternatives for commercial viability. The aim of this study was to develop a modified culture media for Chaetoceros gracilis utilizing locally available fertilizers and vitamins. In the first experiment, the cell density of C. gracilis across four fertilizers combinations (T1, T2, T3 and T4) with three replicates was evaluated to identify the best performing fertilizers recipe. The significantly higher cell density was observed in T1, where a combination of urea, TSP, mineral mix, EDTA, silicate gel, NPK, compost were used, than the other treatments where one or more ingredients were missing. The growth curve showed that with 1 ml/L fertilizers combination of T1 cell density peaked (21.8×10^5 cell/ml) at day three with the death phase starting at day 04. In the second experiment, the effect of vitamin addition was evaluated with T1 considering as control (V0-without vitamin supplement) and, the Multivitamin-Zinc B and Neobion addition with T1 as treatment V1 and V2, respectively. While Neobion addition significantly increased cell density, multivitamin-Zinc B addition reduced the cell density. Finally, the potentiality of continuous culture of C. gracilis with the modified fertilizer media (V2) was evaluated. The cell density in 300 L tank culture starting from 6.6×10^5 cell/ml peaked 23.8 ×10^5 cell/ml at day two and remained relatively static until investigation finished with the supplement of V2 media two days interval. The present study suggest that development of modified fertilizer media using affordable, locally sourced ingredients for algae cultivation in the hatcheries and aquaculture industry could create an alternative to relying on pure laboratory-grade media.