Abstract

The aim of this study was to evaluate the productivity of microalgae Chlorella sorokiniana UTEX 1230 with two different foliar fertilizers used in agriculture and the comparison with the nutrient medium Kolwitz (K3).Variables assessed were cell growth, productivity, chlorophyll concentration, fluorescence (Fv/Fm), proteins, and carbohydrates. Two commercial fertilizers with NPK 20-20-20 and NPK 22-10-7 formula were used as nutrient media. The study was conducted at the Institute of Ecosystem Studies, Florence, Italy, in 2014. Each experiment was repeated five times using three replicates in each experiment under a light intensity of 150 μmol photons m2/s, temperature 28 °C and CO2/air (2:98v/v). The culture media were prepared by using the following fertilizers: 1) NPK 20-20-20 (1.00 g/l) + 0.27 g/l MgSO4.7H2O, 2) NPK 22-10-7 (+2 MgO) (1.00 g/l) + 0.27 g/l MgSO4.7H2O, 3) NPK 22-10-7 (+2 MgO) (1.00 g/l), 4) NPK 20-20-20 (1.00 g/l). The nutrient medium Kolwitz (K3) was used as a control. Higher cell concentrations, productivity, chlorophyll, fluorescence, proteins, and carbohydrates were obtained in cultures grown in the media prepared with magnesium sulfate (NPK 20-20-20 (1.00 g/l) + 0.27 g/l MgSO4.7H2O, and NPK 22-10-7 (+2 MgO) (1.00 g/l) + 0.27 g/l MgSO4.7H2O). Lower biomass growth was obtained in cultures lacking magnesium sulfate. Sulfide and magnesium, as well as the amounts of urea and ammonia in the chemical composition of each fertilizer, had a positive effect on the culture growth and productivity.

 

Keywords: chlorophyll fluorescence, microalgal productivity, total nitrogen, magnesium sulfate.