The maturation of Haematococcus Pluvialis cells and the passage through successive stages of life cycles result in an altered biochemical profile of the cell. Most Haematococcus Pluvialis green stage cells are characterized by high protein content of 29%–45% per dry weight (d.w.). Protein content in palmella decreases to 36% d.w., while in the red stage cells, this content is within a range of 21%–23% d.w. Carbohydrates as starch allow the cell to survive during prolonged stress. In the red cyst, the content increases from 15%–17% d.w. in the green stage to 60%–74% d.w.. As the research demonstrated, total carbohydrates can increase rapidly, by up to 63% d.w, during the first day of stress exposure, decrease to 41% d.w. on the following day, and remain at this level until the end of the cultivation.

1. Lipids

In the green stage, total lipid content varies from 20% to 25%, with approximately 10% of the lipids composed predominantly of polyunsaturated fatty acids (PUFAs) deposited in chloroplasts. The accumulation of lipids ensues from unfavorable environmental conditions. These include limiting nitrogen and phosphorus content, high salinity, high light intensity, and extreme temperatures. The most effective factor causing the accumulation of lipids in the cell is nitrogen limitation. Studies showed a simultaneous increase in oleic acid content, astaxanthin esters during nitrogen limitation 0.15 g/L,  and high light amounting to 170 µmol photons m−2s−1.

Furthermore, the results obtained indicate a correlation between the stress conditions of algae growth and the increase in the lipid content in the cell. In this case, unfavorable conditions caused a significant increase in the total lipid compared to the control culture.

In the first variant of stress conditions, a complete culture medium without aeration and continuous light with an intensity of 300 µmoL photons m−2s−1 were used.

In the second variant, a medium with no nitrogen, aeration, and the same intensity of light as in the first case was applied. The total lipids content in dry weight was respectively 34.85% and 32.99%.

For the control culture with a complete medium, continuous aeration with the mixture of air (500–700 mL/min) and CO2 (0.3 mL/min) and 12 h of illumination with a white lamp 90 µmoL photons m−2s−1, the total content of lipids was 15.61%.

This study also showed a significant increase in the phospholipid content within cultures maintained in unfavorable conditions. The highest content of neutral lipids and glycolipids was obtained in the first variant of stress conditions, and it was 19.80% and 7.85%, respectively. In contrast, these values were 16.60% and 6.67% for the second variant. Only the content of phospholipids was higher in the second variant and was equal to 9.80%, while for the first variant, it was 9.5%.

The following contents were obtained in the control culture: neutral lipids 9.20%, glycolipids 3.70%, and phospholipids 1.87%. The most common fatty acids in Haematococcus pluvialis cells are palmitic, linoleic and linolenic acid. The fatty acid profile is dependent on the strain. We also noticed that nitrogen reduction significantly impacts the production of fatty acids. Lowering the amount of nitrogen in the culture medium to 1.7 mM led to obtaining 7.60% of fatty acids in dry weight. The culture maintained in a medium with a higher nitrogen content of 4.7 mM presented a lower amount of fatty acids: 2.1% d.w.

In the previous study, it was also demonstrated that the nitrogen content affects the fatty acid profile. With a reduction of nitrogen content to 2 mM, the oleic acid level increases, 50% of the total fatty acid content. The culture of microalga under control conditions that promote the multiplication of the biomass resulted in low total lipid content of 13.6%. This research also proved the influence of stress factors on lipid accumulation in the cell. Biomass cultivation in a medium without nitrogen resulted in the accumulation of lipids at the level of 46.71% d.w.

2. Carotenoids

The carotenoid content also changes during cell transformation. It increases in Haematococcus Pluvialis cell from 0.5% d.w. in the green phase to 2%–5% d.w. in the red phase. Lutein with a content of 70%–80% is the main carotenoid in green cells.

The second component with the highest content is β-carotene (16.70% d.w.), the amounts of violaxanthin and neoxanthin are 12.5% and 8.3% d.w. The compounds mentioned above are not found in red phase cells or are only present in small amounts.

The subsequent pigment, present only in green cells, is chlorophyll, the content of which is 1.5%–2% d.w.. Astaxanthin is the essential carotenoid obtained from Haematococcus Pluvialis, and it is accumulated inside the cell only during the red phase. Its content can reach up to 80%–99% of the total carotenoids. However, it is equally important to carry out more thorough research to optimize the culture process to increase the content of lipids and proteins.