Abstract
Simple SummaryMicroalgae are a valuable natural resource for a variety of value-added products. This determines the relevance of developments aimed at increasing the efficiency of their cultivation. First of all, the growth of microalgae is determined by the impact of light. The main parameters characterizing the light conditions during the cultivation of microalgae are light intensity, duration of lighting, and the use of rays of different spectral composition. Manipulations with the duration of the photoperiod and the use of pulsed light can avoid photodamage of microalgae cells and create conditions for the most efficient absorption of light photons. The optimal light conditions for photosynthesis, growth, accumulation of lipids, fatty acid composition, and carotenes content differ both in different taxonomic groups of microalgae and in different strains of the same species.Microalgae are a valuable natural resource for a variety of value-added products. The growth of microalgae is determined by the impact of many factors, but, from the point of view of the implementation of autotrophic growth, light is of primary importance. This work presents an overview of the influence of light conditions on the growth of microalgae, the content of lipids, carotenoids, and the composition of fatty acids in their biomass, taking into account parameters such as the intensity, duration of lighting, and use of rays of different spectral composition. The optimal light intensity for the growth of microalgae lies in the following range: 26−400 µmol photons m−2 s−1. An increase in light intensity leads to an activation of lipid synthesis. For maximum lipid productivity, various microalgae species and strains need lighting of different intensities: from 60 to 700 µmol photons m−2 s−1. Strong light preferentially increases the triacylglyceride content. The intensity of lighting has a regulating effect on the synthesis of fatty acids, carotenoids, including β-carotene, lutein and astaxanthin. In intense lighting conditions, saturated fatty acids usually accumulate, as well as monounsaturated ones, and the number of polyunsaturated fatty acids decreases. Red as well as blue LED lighting improves the biomass productivity of microalgae of various taxonomic groups. Changing the duration of the photoperiod, the use of pulsed light can stimulate microalgae growth, the production of lipids, and carotenoids. The simultaneous use of light and other stresses contributes to a stronger effect on the productivity of algae.
Highlights
Microalgae are a large group of photoautotrophic organisms, as well as organisms capable of heterotrophic, mixotrophic, and photoheterotrophic existence [1,2]
Of significant interest to the food and feed industry is the ability of microalgae to produce carotenoids such as β-carotene, astaxanthin, lutein, as well as lipids containing a wide variety of fatty acids, including long-chain polyunsaturated fatty acids (PUFAs) from the omega-3 and omega-6 [7,8,9,10,11,12,13] group
Light is a prerequisite for the photoautotrophic growth of microalgae
Summary
Microalgae (eukaryotic and prokaryotic cyanobacteria) are a large group of photoautotrophic organisms, as well as organisms capable of heterotrophic, mixotrophic, and photoheterotrophic existence [1,2]. Other species are adapted to growth in direct sunlight, for example, in polar, tropical deserts [30,31,32], on salt marshes and other open surfaces [33,34,35,36], where the light intensity can reach 2000 μmol photons m−2 s−1 [15] When cultivating microalgae, both natural and artificial lighting are used. The purpose of this article is to summarize information on the effect of lighting conditions on the growth of microalgae, the content of lipids, carotenoids, and the composition of fatty acids in their biomass, taking into account such parameters as the intensity, duration of lighting and the use of rays of different spectral composition. We assume that the information provided will be valuable for further developments to increase the efficiency of cultivation of microalgae species and obtain value-added products from their biomass, such as carotenoids, lipids, and fatty acids by changing certain lighting parameters
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