Production of iron-rich biomass using Chlorella vulgaris cultivation under iron stress

Fertilizers play a crucial role in enhancing the yield of agricultural crops and their market value. Therefore, it is essential to have large-scale, low cost, eco-friendly, broad-spectrum, and clean production of fertilizers. This study aims to prepare an iron-rich biomass, which holds the potential to serve as a biofertilizer, through the cultivation of Chlorella vulgaris microalgae under iron stress conditions. To attain this objective, three different iron sources were examined by supplementing them to the microalgal growth culture medium, namely ammonium ferric citrate, FeCl3, and EDDHA-Fe, each at varying concentrations of iron. The experimental findings revealed that, under iron stress conditions, the addition of ammonium ferric citrate as the iron source to the microalgal growth culture medium resulted in a microalgal biomass with a maximum iron content of 4.88 % by weight. However, the iron content of the obtained biomass from the culture media sourced from FeCl3 and EDDHA-Fe reached a maximum of only 2.01 % and 3.55 % by weight, respectively. Ultimately, the efficacy of the iron-rich microalgal biomass was evaluated by utilizing it during corn cultivation, in conjunction with regular microalgal biomass, ammonium ferric citrate, and the iron-deficient soil (as control) samples. The dry weight of the corn stem cultured with iron-rich biomass was 13 %, 55 %, and 152 % higher, compared to those cultured with regular microalgal biomass, ammonium ferric citrate, and the iron-deficient soil, respectively.