Abstract
Light (wavelength, intensity, and light/dark cycle) have been considered as one of the most important parameters for microalgae cultivation. In this paper, the effect of medium frequency intermittent light on Auxenochlorella pyrenoidosa (formerly Chlorella pyrenoidosa) cultivation was investigated. Three parameters of intermittent light, light intensity, light/dark ratio, and light/dark cycle were employed and the influence of these parameters on the productivity of Auxenochlorella pyrenoidosa was studied. The biomass yield and growth rates were mainly affected by the light fraction and cycle time. Light with 220 μE m−2 s−1 light intensity was determined as the optimal light intensity for biomass production. At the light intensity of 420 μE m−2 s−1, the results indicated that the intermittent light improved the biomass production with larger light/dark ratio compared with the continuous light. At a lower mean light intensity over time, the intermittent light should be more suitable for biomass growth and the decrease in the light/dark ratio (L/D) will lead to a higher biomass productivity. The light/dark cycle time has little influence on the biomass yield.
Highlights
Photosynthetic microorganisms have received growing attention, especially for mass cultivation of microalgae, due to their possible production of health foods, biofuels, and for carbon dioxide reduction
The results obviously indicate that the biomass productivity increased in with the biomass productivity because the light energy support to photosynthesis by intermittent light the increase in L/D, which agreed well with previous studies
These may be because the red light wavelength (620–630 nm) was close to the photosynthetic absorption spectrum of 680 nm when compared with the white light (380–760 nm)
Summary
Photosynthetic microorganisms have received growing attention, especially for mass cultivation of microalgae, due to their possible production of health foods, biofuels, and for carbon dioxide reduction. Light attenuation in microalgae cultivation systems has been reported as a major bottleneck in microalgal production. Numerous studies have indicated that light intensity and light wavelength change the results in increasing or decreasing the biomass and metabolite yields [3,4]. Carvalho et al [6] summarized previous studies that have suggested that a light source with narrower spectral outputs close to the photosynthesis absorption spectrum (680 nm) are photosynthetically more efficient. The excessive and insufficient light intensity result in decreases to the biomass productivity. Due to the light attenuation in microalgae cultivation systems, an efficient light energy supply has been reported as the greatest scientific and technological challenge in the research and the development of the cultivation of photosynthetic microorganisms [10]
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