The Role of Photo-Cycles in the Modulation of Growth and Biochemical Profile of Microalgae: Part I—Food Interest Compounds

Abstract

The objective of this work was to evaluate the effect of different photo-cycles on the growth and biochemical profile of Scenedesmus obliquus CPCC05, focusing on food interest compounds. The photo-cycle conditions were separated into three groups: long-term photo-cycles (24:0, 22:2, 20:4, 18:6, 12:12, and 10:14 (h:h)), frequency photo-cycles (2, 4, 8, 12, 24, and 48 times per day (t/d)), and short photo-cycles (0.91:0.09, 0.83:0.17, 0.75:0.25, and 0.50:0.50 (s:s)) of light:dark, respectively. The results showed these microalgae can store enough energy to support cell growth for continuous periods of up to 2 h in the dark, without affecting the productivity of the process. This 2 h, when divided into 2 cycles per day (2 t/d), showed the best growth condition (3700 mg L−1), generation time (14.40 h), and maximum biomass productivity (21.43 mg L h−1). This photo-cycle of 2 t/d was also the best condition for the production of total sterols. However, the values of polyunsaturated fatty acids, lipid content, and amino acids obtained higher yields in the short photo-cycle of 0.75:0.25. Thus, the modulation of light cycles becomes an important tool for boosting and directing the production of target molecules in phototrophic cultures of microalgae.

Growth Efficiency of Chlorella sorokiniana in Synthetic Media and Unsterilized Domestic Wastewater

“…In experiments on the effect of light exposure on the productivity of microalgae, various photoperiods (e.g., 12:12, 14:10, 16:8, 24:0-h light/dark cycles) were tested [ 17 , 18 , 19 ]. It has been shown that a longer period of darkness can reduce the productivity of algae as it inhibits the functioning of the cell photosystems [ 20 ]. The optimal light/dark cycle determines the algal culture growth rate, total biomass yield, accumulation of proteins, lipids, and carbohydrates, as well as the uptake of macro- and microelements [ 21 , 22 ].…”

Optimization of Photoautotrophic Growth Regimens of Scenedesmaceae alga: The Influence of Light Conditions and Carbon Dioxide Concentrations

“…Con-sidering that the high tested light intensities can cause photoinhibition of microalgae [35], in this work, cultivation was carried out both under continuous and periodic light. It is also known that the use of different photoperiods makes it possible to change the biochemical composition of microalgal cells [9,36]. A series of experiments were carried out to analyze the effects of daily PPFD (37.44-112.32 mol m −2 day −1 ), photoperiods (16 h and 24 h), and various CO 2 concentrations (1-4%) on algal growth, biomass productivity, nutrient removal, and accumulation of selected metabolic products in a well-controlled Labfors 4 Lux photobioreactor.…”