Generalities
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1.1.4. Biochemical composition of microalgae
The interest of microalgae lies in the diversity of their biochemical compositions. The main
difference between this biomass and other plants is their richness in lipids, proteins,
polysaccharides, vitamins, pigments and antioxidants (Dejoye Tanzi, 2013).
Table 3 lists the biochemical composition of some microalgae.
Table 3: Biochemical compositions of microalgae (Becker, 2007).
Microalgae
Proteins (%)
Polysaccharides (%)
Lipids (%)
Chlorella vulgaris
51-58
12-17
14-22
Dunaliella salina
57
32
6
Porphyridium cruentum
28-39
40-57
9-14
Spirulina platensis
46-63
8-14
4-9
Scenedesmus obliquus
50-56
10-17
12-14
Synechococcus sp
63
15
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1.1.5. Mechanism of photosynthesis in microalgae
Microalgae are photosynthetic organisms that have the ability to capture light via the absorption
of photons by photosynthetic units and convert this light energy into chemical energy through
their main pigments: chlorophyll(a), chlorophyll(b), xanthophyll and carotene (Geetanjali &
Sen, 2017).
Photosynthesis is represented globally by the following equation:
nCO2 + nH2O
(CH2O) n + nO2
This global reaction takes place in two stages (light reaction and dark reaction) separated in
space and time (Figure 2).