Effects of different light intensity on the growth of Chorella vulgaris

Abstract:

[Objective] This study provides the theoretical basis for optimal cultivation and nutrient utilization of Chorella vulgaris. The study aimed to discuss the effect of varying light intensity (0, 1 000, 3 000, 5 500, 7 000, 9 000 lx) on the growth of Chorella vulgaris. [Methods] The experiment was conducted under aeration rate of 20% and at 20 ℃, and the Chorella vulgaris was cultivated on the BG-11 culture medium under stable condition. Parabolic regression curves between light intensity and the maximum optical density (OD_max) and the maximum growth rate (μ_max) were created. [Results] The growth rates varied different in different light intensity, and the chlorophyll a concentrations increased in the initial time until reached the maximum value and then decreased dramatically. The intensity of 5 500 lx was most suitable for the Chorella vulgaris growth. The demand of phosphorus of algal growth was greater than the nitrogen. [Conclusion] The mathematical relationships between light intensity and OD_max, μ_max simulated by cubic curve equation were shown as follows: OD_max=-1E–07x²+0.001 6x+0.105 5 (R²=0.9872, 0≤x≤9 000 lx), μ_max=-2E–08x²+0.000 3x-0.004 2 (R²=0.998 6, 0≤x≤9 000 lx).

Key words:Light intensity|Chorella vulgaris|Growth rate|Parabolic regression curves