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The effects of light spectra on cell concentration, cell size, biomass production, proximate composition, pigment content, and fatty acid content in Chlorella vulgaris during two growth phases were measured. Growth rates were higher with white (0.70 division day−1) and blue light (0.67 divisions day−1). Cell size was greater in the exponential growth with yellow light (16.29 μm) versus blue light (14.26 μm). Higher organic dry weight (ODW) values were observed during exponential growth under green light (70.58 pg cell−1) compared with white light (36.56 pg cell−1). Proximate composition differed significantly by effect of light spectra and growth phases. Protein content was significantly higher in the exponential growth with white light (34.42%) and green (31.64%) light. Carbohydrate levels were significantly higher during stationary growth under yellow light (27.05%). In the exponential growth, lipid content was significantly higher with blue light (18.74%). Biomass productivity was highest in exponential growth phase with blue light (0.064 gL-1 day-1), meanwhile, in stationary growth phase yellow light (0.031 gL-1 day-1). Chlorophyll a and carotenoid levels were significantly greater during exponential growth with green and yellow lights. Fatty acid content was significantly modified by the light spectra and growth phase. The predominant saturated fatty acid was C:16:0 (palmitic acid), ranging between 10.26 (green light and exponential growth) and 20.01% (white light and stationary growth). The content of C18:1n-9 was higher (28.34 %) with the white light in the stationary growth, and C18:3n-3 content was greater with white (41.41%) and blue light (40.82%) in the exponential growth. It was concluded that blue light is the most suitable condition to induce biomass productivity and lipid content on both growth phases. Blue light during the stationary growth phase induces the production of lipids and saturated fatty acids (SFAs) which are suitable for biodiesel production.

The goal of this work was to evaluate the protective effect of glycerol and PEG-methyl ether methacrylate (PEGMA) coatings, as well as CaCl2 concentration, on the viability of alginate-immobilized Synechococcus elongatus after cold storage. Neither the growth rate nor the generation time of alginate-immobilized S. elongatus was affected by the concentration of CaCl2 after cold preservation by refrigeration at 4 °C for 3.4 years (p > 0.05). However, the type and concentration of the coating, glycerol, or PEGMA, of the alginate beads, affected both growth rate and generation time (p

We determined the effects of two nitrogen sources (ammonium and nitrate) and two irradiance levels (50 and 200 μmol photons m−2 s−1) on the growth rate, cell size, proximate composition, pigment content, and photosynthesis of the unicellular red alga, Porphyridium cruentum. Irradiance significantly affects growth rate, as well as carbohydrate, protein, and phycoerythrin content. Nitrogen form significantly affects cell size, total dry weight, organic dry weight, ash content, carotene content, phycocyanin content, allophycocyanin content, maximum relative electron transport rate (rETRm), and photosynthetic efficiency (α). However, the irradiance and nitrogen source had significantly interaction with the content of lipids and chlorophyll a content, relative electron transport rate (rETR), and irradiance of saturation (Ik). These findings demonstrate that irradiance and nitrogen source influence the metabolism of P. cruentum and that the combination of these two variables induces the production of chemical products for biotechnological, aquaculture, and nutraceutical industry.