Effects of phosphorus, sulfur and carbon dioxide concentrations on growth and carbohydrate accumulation of Desmodesmus insignis

Abstract:

[Objective] To determine the effect of concentrations of P, S and CO₂ on the growth and total carbohydrate accumulation of Desmodesmus insignis, the algae were cultivated in modified BG-11 medium containing 8 different initial phosphorus and sulfur concentrations and 4 different carbon dioxide concentrations. [Methods] Biomass and total carbohydrate content were measured by dry weight and phenol-sulfuric acid method, respectively. [Results] The highest biomass concentration reached 6.37 g/L under 0.460 mmol/L K₂HPO₄ and the maximum content and productivity of carbohydrate was 45.40% of dry weight and 0.20 g/(L·d) under 0.230 mmol/L K₂HPO₄, respectively. High MgSO₄ concentration could promote the growth and carbohydrate accumulation of Desmodesmus insignis. The highest biomass concentration and the maximum content and productivity of carbohydrate were achieved at 1.217 mmol/L, 0.609 mmol/L and 1.824 mmol/L MgSO₄, which was 7.02 g/L, 51.60% of dry weight and 0.26 g/(L·d), respectively. In addition, the highest biomass concentration and the maximum content and productivity of carbohydrate were 6.81 g/L, 44.03% and 0.20 g/(L·d) when 3% (V/V) CO₂ was used. [Conclusion] Thus, the concentrations of P, S and CO₂ which were beneficial to the growth and carbohydrate accumulation were 0.230 mmol/L, 1.824 mmol/L and 3% (V/V), respectively.

Key words:Desmodesmus insignis;phosphorus;sulfur;carbon dioxide;biomass;carbohydrate