Manipulation of nitrogen levels and mode of cultivation are viable methods to improve the lipid, fatty acids, phytochemical content, and bioactivities in Chlorella minutissima

Abstract

The effect of nitrogen (N: low = 2% N or moderate = 10% N) levels and cultivation (photoautotrophic or mixotrophic) modes on the biochemicals in Chlorella minutissima was evaluated using a mass culture system. Moderate N and mixotrophic cultures had higher biomass, protein, carbohydrate content and photosynthetic pigments than the low N and photoautotrophic treatments. In contrast, lipid and fatty acid content of the low N and photoautotrophic treatments were higher than in the moderate N and mixotrophic cultures. More phytochemicals were accumulated in moderate N and mixotrophic cultures which corresponded to better antioxidant capacity in the extracts. The most potent (0.7 mg · mL(-1) ) acetylcholinesterase inhibitory activity was displayed by moderate N and mixotrophic treatment. Approximately 60% of the extracts exhibited a noteworthy antimicrobial activity regardless of the N levels and cultivation modes. Thus, moderate N level enhanced the phytochemicals and biological activities of C. minutissima cultured under a mixotrophic system.

Effects of Nitrogen Availability on the Antioxidant Activity and Carotenoid Content of the Microalgae Nephroselmis sp

“…extract was twice as active under N-replete conditions than under N-limited or starved conditions ( Figure 4 ). Those results are in agreement with the few studies that have evaluated the effects of N-limitation on antioxidant activities [ 25 , 29 , 35 , 36 ]. Çakmak et al [ 25 ] and Aremu et al [ 35 , 36 ] showed the negative impacts of N-starvation on the antioxidant activity of Chlamydomonas reinhardtii and Chlorella strains, respectively.…”

“…However, the influence of nitrogen availability on antioxidant compounds is species-specific, and high antioxidant activity due to over-accumulation of secondary carotenoids under nutrient stress should not be generalized to all species. Indeed, only some chlorophytes species are able to accumulate secondary carotenoids [ 17 ], whereas several studies describe a decrease of antioxidant activity and primary carotenoids with N-starvation [ 25 , 29 , 35 , 36 ].…”

Enhancing Secondary Metabolites in Chlorella Sorokiniana Using Alternative Medium with Vinasse

“…Phenols and flavonoids are the secondary metabolites more produced by microalgae when in detriment of UV exposure or under stress conditions induced by the culture medium. Those compounds are highlighted in cell protection and have an special role against the presence of harmful compounds [34,35,36]. Our results corroborate with the previous authors (Table 2), since microalgae biomasses were grown under UV radiation and used culture medium enriched with vinasse and NPK (EA-Cs2).…”

“…Some studies demonstrate a ratio between presence/absence of UV radiation and the addition/restriction of nutrients with the synthesis of secondary metabolites. [36] Some bioactives have variation when produced by Chlorella minutissima grown with different doses of nitrogen in a mixotrophic and in a photoautotrophic systems, and the authors concluded the presence of this nutrient, especially in mixotrophic conditions, increased the production of secondary metabolites which reinforces our results. Under similar conditions, we've added NPK, with no detriment to carbon sources as the sugars from the vinasse, the nutrients were assimilated by C .sorokiniana during the dark periods, characterizing mixotrophic cultivation.…”

Characterization of a Chlorophyta microalga isolated from a microbial mat in Salar de Atacama (northern Chile) as a potential source of compounds for biotechnological applications

“…However, biomass production has been achieved, and bioactive compounds have been obtained from microalgae isolated from extreme environments on Gran Canaria Island (Rodriguez‐Meizoso et al ). Several microalgae, such as species of Chlorella , Spirulina , Isochrisis , and Dunaliella , are widely recognized as potential sources of nutrients, including fatty acids, amino acids, minerals, and other essential compounds (Chu ; Aremu et al ; Greque de Morais et al ). In particular, the polyunsaturated fatty acid (PUFA) content in microalgae is difficult to predict at the levels of genus and species, making it difficult to select appropriate strains for biotechnological applications aimed at high lipid yield (Lang et al ).…”