Influence of nitrogen, phosphorus and sulfur concentration on bioplastic and FAMEs production in Scenedesmus sp.

Abstract

Microalgae can fix CO2 into valuable molecules; these products are expected to sustainably replace petroleum-derived plastics and oils. The biorefinery strategies are implemented to simultaneously generate high-value products by extracting a fraction of the microalgae. This research evaluated the growth kinetics of Scenedesmus sp. under different macronutrients such as nitrogen, phosphorus, and sulfur (low, medium and high concentration). The correlation of cell growth behavior with biochemical characterization was determined with emphasis on the potential of the microalgae to use as raw material for bioplastic production. The results showed. that a high sulfur concentration has influenced and increased the cell growing reaching 1.42 g L^−1 at 15th cultivation day compared with the nitrogen and phosphorus variation. The content of carbohydrates in the biomass was enhanced under limitation of nitrogen and phosphorus. The same statement was proved for the PHA accumulation reaching 9.5 ± 0.83 % and 6.4 ± 0.32 % DW (dry weight) respectively. Deprivation of nitrogen, phosphorous and sulfur improved the microalgae culture for lipids production. In the present study the higher lipid content (273 mg g^−1) was observed under phosphorus limitation. The monitoring of FAMES considering former condition in the medium revealed high content of palmitic [30 ± 1.5 %TFA], stearic (C18:0) [1.8 ± 0.11 %TFA], and oleic acid. Therefore, these results lead to observing the impacts of macronutrients (N, P, S) on the microalgae growth and determined the better conditions for the accumulation of macromolecules that can be extracted under biorefinery concepts valorizing the biomass for bioplastic production and other biomolecules for future industrial applications.