Abstract
The development of efficient, environmentally friendly, low-cost approaches used to boost the growth of microalgae is urgently required to meet the increasing demands for food supplements, cosmetics, and biofuels. In this study, the growth promotion effects of protocatechuic acid (PCA) in the freshwater microalga Euglena gracilis were confirmed for the first time. PCA is a simple phenolic compound derived from natural plants and has a range of biological functions. The highest biomass yield, 3.1-fold higher than that of the control, used at 1.3 g·L−1, was obtained at 800 mg·L−1 of PCA. The yields of the metabolites chlorophyll a, carotenoids, and paramylon in the presence of PCA at 800 mg·L−1 were 3.1, 3.3, and 1.7 times higher than those of the control group, respectively. The highest paramylon yield was achieved at a lower dosage of PCA (100 mg·L−1), which is considered to be feasible for economic paramylon production. The growth and biosynthesis of metabolites stimulated by phytochemicals such as PCA could be an efficient and cost-effective strategy to enhance the productivity of microalgae in large-scale cultivations.
Highlights
Microalgae are considered to be one of the most promising feedstocks for the sustainable production of commodities such as biofuels, foods, cosmetics, and pharmaceuticals [1,2]
Various approaches for optimizing E. gracilis cultivation have been trialed in the past decade, including modifying the alga strains by genetic engineering [5,6], but technical difficulties remain
Previous studies have successfully addressed the improvement of biomass and metabolite production of microalgae using genetic engineering [7,8]
Summary
Microalgae are considered to be one of the most promising feedstocks for the sustainable production of commodities such as biofuels, foods, cosmetics, and pharmaceuticals [1,2]. Euglena gracilis is a freshwater flagellate which absorbs light energy and converts it into chemical energy, besides taking up nutrients from the environment This alga has considerable potential value because of the compounds it produces, which include vitamins, proteins, β-1,3-glucan (paramylon), essential amino acids, and fatty acids [3]. Previous studies have successfully addressed the improvement of biomass and metabolite production of microalgae using genetic engineering [7,8] The use of chemical fertilizers causes several problems, including issues of cost and environmental pollution Some organic sources, such as glucose, fructose, and maltose, can enhance the growth of microalgae [10,11]. The exploration of more eco-friendly, cheaper, and safer sources to promote microalgae biomass growth is necessary to achieve their economically feasible bio-production
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