Influence of Photoperiods on Microalgae Biofilm: Photosynthetic Performance, Biomass Yield, and Cellular Composition

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.

Light-Emitting Diode Power Conversion Capability and CO2 Fixation Rate of Microalgae Biofilm Cultured Under Different Light Spectra

“…Figure S3 shows the lipids, proteins and carbohydrates contents for the C. ellipsoidea and C. pyrenoidosa cultured under different LEDs. It was found that the main organic components in the microalgae represented approximately 80% of microalgae dry biomass, which were consistent with the literature [35]. Based on the cellular composition and power consumption of different LEDs, we determined the conversion capabilities of LED power-to-lipid, power-to-protein, and power-to-carbohydrate.…”

“…Then, these filtration membranes were put into the biofilm culture bioreactors (polymethyl methacrylate chambers: 400 × 200 × 200 mm), containing the BG-11 culture medium solidified with 1% agar (see Supplementary Materials Tables S1 and S2 for the details) [34]. As shown in Figure 1, these bioreactors were placed into an incubator to maintain a proper temperature (25 ± 1 • C) for microalgae growth [35]. The inside of these bioreactors was aerated with compressed air enriched with 1% CO 2 (vol/vol) at a rate of 0.1 VVM (volume of air per volume of culture per minute).…”

Assuaging Microalgal Harvesting Woes via Attached Growth: A Critical Review to Produce Sustainable Microalgal Feedstock

“…This led to photoinhibition, reducing the microalgal biomass productivity [118]. The short timescale of photoperiods can be efficient to enhance the microalgal biofilm formation in relation to the photosynthetic electron transfer chain reaction, influencing the microalgal photosynthetic performance [120]. Zhang et al [120] and Martín-Girela et al [121] proved in their research that Nannochloris oculata, Chlorella pyrenoidosa, and Chlorella sp.…”

Photoperiod influenced the growth and antioxidative responses of Chlorella vulgaris, Isochrysis galbana, and Tetraselmis chuii

“…Microalgae are photosynthetic organisms that use light, carbon dioxide, and water to produce food in the form of biological macromolecules like proteins, lipids, and carbohydrates (Morales et al, 2019). Light and photoperiod affect the growth and yield of microalgae during cultivation (Ahmad et al, 2020;Zhang et al, 2019). In addition, the period of light and dark exposure until the saturation point at which the maximal photosynthetic rate is reached may control cellular contents (Darvehei et al, 2018;Sirisuk et al, 2018), including chlorophyll and antioxidants (Maroneze et al, 2016).…”

“…Up until now, most of the research conducted with microalgae focused on biomass production (Che et al, 2019;Kato et al, 2019;Ren et al, 2020;Vendruscolo et al, 2019;Zhang et al, 2019) and determination of the cellular contents such as lipid (Che et al, 2019;Kato et al, 2019;Medved et al, 2020;Ren et al, 2020;Vendruscolo et al, 2019;Zhang et al, 2019), fatty-acid (Che et al, 2019;Kato et al, 2019;Vendruscolo et al, 2019), chlorophyll (Gonzalez-Camejo et al, 2019;Patel et al, 2019;Vendruscolo et al, 2019), protein (Medved et al, 2020;Vendruscolo et al, 2019;Zhang et al, 2019), and carbohydrate content (Chong et al, 2019;Kato et al, 2019;Medved et al, 2020) upon the variations in the light and dark exposure. The role of photoperiods in the development of antioxidants and their responses to microalgae, however, is poorly understood.…”