Time‐ and media‐dependent secondary carotenoid accumulation in Haematococcus pluvialis

Abstract

The green microalgae Haematococcus pluvialis synthesizes secondary carotenoids after exposure to environmental stress, a process that is used for the biotechnological production of astaxanthin (Ax). This study reports, for the first time, the medium-dependent changes in the carotenoid pattern throughout the cultivation process as well as the exact composition of carotenoids and their fatty acid mono-and diesters using LC-MS. Secondary carotenoid formation started immediately upon exposure to nutrient depletion and high light conditions. Ax and its corresponding monoand diesters were detected simultaneously. After 15 days of cultivation, no significant changes were detected in carotenoid composition; however, the ratio between carotenoid mono-and diesters still varied. Main carotenoids were identified as Ax linolenate and Ax oleate, but also five adonirubin and one lutein monoester were detected. The influence of three different autotroph media was studied on carotenoid content, which reached a maximum 16.1 mg/g dry weight. The results indicate that media composition has an influence on the ratio of Ax mono-to diester but not on the qualitative composition of secondary carotenoids in H. pluvialis. Beside the pathway via echinenone, canthaxanthin and adonirubin the results indicate that Ax biosynthesis takes place via another route: from β-carotene via β-cryptoxanthin, zeaxanthin and adonixanthin.

Astaxanthin Preparation by Lipase‐Catalyzed Hydrolysis of Its Esters from Haematococcus pluvialis Algal Extracts

“…Maximal degradation rate of carotenoid esters under optimal reaction conditions was 89.3% (data not shown), whereas the maximal free astaxanthin recovery achieved was 63.2%. TLC detection showed that other carotenoids had also been generated in the reaction, suggesting that other carotenoid esters in the substrates such as adonirubin esters (Grewe and Griehl 2008) might have also been hydrolyzed to the free form during the reaction. Further investigations should be made to identify these by‐products and a nitrogen‐filled obturating reactor should be used to improve the efficiency of reaction.…”

Improvement of lipid production in the marine strains Alexandrium minutum and Heterosigma akashiwo by utilizing abiotic parameters

“…These high-carbon lipids have been proposed as a source of sustainable oil production and thus as a highly feasible alternative in the development of third-generation biofuels. Microalgae also produce other metabolites, such as astaxanthin, lutein, arachidonic, eicosapentaenoic, and docosahexaenoic acids, which are of high economic value, and even toxins such as yessotoxins [5,6,17,36,40]. Recent research has focused on the production and isolation of commercially interesting metabolites, including those derived from microalgae, for a broad range of applications.…”

“…DiVerent techniques are used to modify the biochemical composition of microalgae, including altered environmental parameters, such as light, salinity, or nutrients [29,37,39], and diVerent CO 2 Xow regimes during the aeration of photobioreactors, open ponds, or raceway ponds [11]. These techniques enhance the productivity of speciWc microalgal strains and have been successfully applied to obtain new sources of natural products, e.g., labeled lipids ( 13 C) [1], toxins [14], secondary metabolites (antioxidants, e.g., lutein), pigments (astaxanthin), or PUFAs such as arachidonic acid, eicosapentanoic acid, and docosahexanoic acid [5,6,17].…”

Physiological Limitations and Solutions to Various Applications of Microalgae

“…Nutrient limitation such as nitrogen, phosphorus or sulfur are widely used strategies for inducing astaxanthin accumulation in Haematococcus pluvialis [57,58]. However, nutrient limitation reduces the maximum amount of biomass one can achieve, thereby reducing the total amount of astaxanthin that can be produced.…”