Nitrogen Deficiency-Dependent Abiotic Stress Enhances Carotenoid Production in Indigenous Green Microalga Scenedesmus rubescens KNUA042, for Use as a Potential Resource of High Value Products

Abstract

<jats:p>The microalgal strain Scenedesmus rubescens KNUA042 was identified in freshwater in Korea and characterized by evaluating its stress responses in an effort to increase lipid and carotenoid production. Under a two-stage cultivation process, the algal strain that generally exhibits optimal growth at a nitrate (source of nitrogen) concentration of 0.25 g L−1 was challenged to different exogenous stimuli—salinity (S), light intensity (L), combined L and S (LS), and nitrogen deficiency (C)—for 14 days. Lipid production and carotenoid concentration increased in a time-dependent manner under these physicochemical conditions during the culture periods. Lipid accumulation was confirmed by thin layer chromatography, BODIPY staining, and fatty acid composition analysis, which showed no differences in the algal cells tested under all four (C, S, L, and LS) conditions. The quality of biodiesel produced from the biomass of the algal cells met the American Society for Testing and Materials and the European standards. Total carotenoid content was increased in the LS-treated algal cells (6.94 mg L−1) compared with that in the C-, S-, and L-treated algal cells 1.75, 4.15, and 1.32 mg L−1, respectively). Accordingly, the concentration of canthaxanthin and astaxanthin was also maximized in the LS-treated algal cells at 1.73 and 1.11 mg g−1, respectively, whereas lutein showed no differences in the cells analyzed. Conversely, chlorophyll a level was similar among the C-, S-, and LS-treated algal cells, except for the L-treated algal cells. Thus, our results suggested that S. rubescens KNUA042 was capable of producing carotenoid molecules, which led to the maximum values of canthaxanthin and astaxanthin concentrations when exposed to the combined LS condition compared with that observed when exposed to the salinity condition alone. This indicates that the algal strain could be used for the production of high-value products as well as biofuel. Furthermore, this article provides the first evidence of carotenoid production in S. rubescens KNUA042.</jats:p>

Influence of environmental conditions on lipid accumulation by the alga Halochlorella rubescens

“…The fatty acid profile of H. rubescens also shows that this microalga is suitable for biodiesel production, as well as cosmetic and pharmaceutical applications. Similarly, the fatty acid profile of Scenedesmus rubescens KNUA042 includes major fatty acids such as palmitic acid, oleic acid and linoleic acid (Jo et al 2020). Lin et al (2012) reported the profile of S.…”

Diversity and Distribution of Carotenogenic Algae in Europe: A Review

“…Carotenoid composition and content for this alga depends on strain and/or culturing conditions. Jo et al [ 189 ] reported that the main secondary carotenoids were canthaxanthin and astaxanthin ( Table 1 ). Their contents after carotenogenesis induction are c.a.…”

Identification and characterization of <italic>Dunaliella salina</italic> OH214 strain newly isolated from a saltpan in Korea

“…Nitrogen concentration is an important factor that regulates biomass or carotenoid productivity in microalgae (Jo et al 2020, Minyuk et al 2020. Because nitrogen is a major component of proteins, nitrogen-deficient conditions cause retardation or terminate cell growth and trig-…”

“…5E). Therefore, the high carotenoid content per cell number in nitrogen-deficient culture can be explained by the enlarged cell size due to the inhibition of cell division (Jo et al 2020, Minyuk et al 2020, Yaakob et al 2021). These results indicate that nitrogen shortage can induce carotenoid accumulation; therefore, nitrogen-deficient cultivation is suitable for the production of β-carotene and lutein together from the D. salina OH214 strain.…”