Abstract
Microalgae have immense potential as biological sources to produce biofuels and high-value biomolecules. Biofilm-based microalgae cultivation has attracted much interest recently because of its high biomass productivity, reduced water use, and low cost of harvesting. This study aimed to understand the effect of photoperiod on three microalgae biofilms, including Nannochloris oculata, Chlorella sp., and Chlorella pyrenoidosa. The examined photoperiods were 3:3 s, 5:5 s, 30:30 min, 12:12 h (light-period-to-dark-period ratio), and continuous lighting. By determining the maximum quantum yield and relative electron transport rate of photosystem II, we found that photoperiods on the seconds scale improved photosynthetic performance of microalgae biofilm. Biomass yield and lipid content of these three microalgae cultured under the photoperiod with the seconds scale increased by 11%–24% and 7%–22%, respectively, compared with those cultured under continuous lighting. In addition, the photoperiods of 3:3 s, 5:5 s, 30:30 min, and 12:12 h were beneficial for protein synthesis. These results have important implications in establishing suitable light regimes for microalgae biofilm-based cultivation systems.
Highlights
Microalgae are able to perform photosynthesis to produce lipids and other valuable biological compounds
It was found that the chlorophyll−a contents were much higher than the chlorophyll−b contents in these three microalgae, and the total chlorophyll contents were much lower in N. oculata and Chlorella sp. than in C. pyrenoidosa, which were consistent with the literature [35,36,37,38,39]
The results of this study indicated that the photoperiods significantly influenced microalgae biofilms
Summary
Microalgae are able to perform photosynthesis to produce lipids and other valuable biological compounds. Because of their fast growth rate, low nutrient requirements, and high lipid contents, microalgae have immense potential as biological sources to produce biofuels, high-value biomolecules, and feeds [1,2,3,4]. Extensive studies have reported that many factors can affect performance of microalgae biofilms cultivation, such as light condition, amount of CO2 supplementation, both nutrient type and concentration, temperature, etc. Photoperiod plays an important role in microalgal photosynthesis and growth [6,15,18,19]
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