# Sustainable Microalgae and Cyanobacteria Biotechnology
## 2 Applications of Biotechnology on Microalgae and Cyanobacteria Utilization
### High Valuable Compounds from Microalgae  
#### 2.1.1 Pigments  
Pigments in microalgae are important because they are cytoplasmic compounds with a diverse chemical structural composition and three distinct activities, namely light energy capture, electron transfer reactions, and antioxidant activities. All these reactions are part of a complex photosynthetic chain mechanism system that performs functions such as light harvesting, energy transfer, photochemical redox reactions, and photoprotection. It is divided into three major pigment classes: chlorophylls, carotenoids, and phycobilins, all of which are light energy harvesting molecules. These pigments could absorb light quanta and then deliver photon energy to sites where the photosynthesis process began [11]. Table 2 compares the pigment components found in microalgae and cyanobacteria. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sector**} & \multicolumn{3}{c}{**Stages**} \\ \cline{2-4}  & **First Stage** & **Second Stage** & **Third Stage** \\ \hline Bioenergy & Bioprospecting of biofuels & Optimization of the production process & Use of biocatalysts, or new routes of biofuels production \\ \hline Health care, therapeutics & Bioprospecting of health care compounds & Protein recombinant technology & Clinical assays for biomedical purposes \\ \hline Environment & Biodegradation and biodegradation assays & Selection of phycromediation or wastewater treatment process & On-site applications in which an integrated process has been developed \\ \hline Aquaculture & Selection of strains and evaluation for specific fish or crustacean aquaculture & Balanced diets design & Feed additive production and implementation in aquaculture farms \\ \hline Cosmetics & Bioprospecting of natural products from microalgae & Skin applications & Medical care supplements for skin applications \\ \hline Foods & Natural products & Probiotics & Food supplements \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Microalgal biotechnology developments visualized in terms of stages according to the application sector. \begin{table}
\begin{tabular}{l l l l} \hline \hline \multicolumn{1}{l}{**Characteristics**} & \multicolumn{1}{l}{**Chlorophyll**} & \multicolumn{1}{l}{**Carotenoids**} & \multicolumn{1}{l}{**Phycobilins**} \\ \hline \multirow{2}{*}{Common found place} & \multirow{2}{*}{Green plant and cyanobacteria} & Brown algae (phaeophyta) & \multirow{2}{*}{Red algae (rhodophyta) and cryptomads and cyanobacteria} \\  & & and green algae (chlorophyta) & & \\ \hline Structural formulae & Tetrapyrrole ring with a central magnesium atom & \begin{tabular}{l} Polyene chain consisting of \\ 9–11 double bonds and \\ terminating in rings \\ \end{tabular} & Tetrapyrrole unit with open chain of four pyrrole rings (tetrapyrrole) \\ \hline Absorption wavelength & \begin{tabular}{l} 450–475 nm \\ (blue/blue–green); 615–675 \\ nm (red) \\ \end{tabular} & \
\begin{tabular}{l} 400–550 nm (blue to green \\ light) \\ \end{tabular} &
\begin{tabular}{l} 500 nm to 650 nm (green–red) \\ \end{tabular} \\ \hline Water solubility & Insoluble in water & Insoluble in water & Soluble in water \\ \hline \multirow{2}{*}{Examples} & Five types of chlorophylls a, b, c and d & Xanthophylls (molecules & \\  & & containing oxygen) and caroten (oxygen free & phycorythrin, phycocyanin, \\  & & concule). & \\ \hline \multirow{2}{*}{Functions} & Colour pigment used in photosynthesis as a photoreceptor & Biological abilities, including photosynthesis, photoproduction, plant coloration, and cell signaling. & Supplement the light-capturing ability especially red, orange, yellow, and greenlight. \\ \cline{2-4}  & & & \\ \end{tabular}
\end{table} 
Table 2: Differences in pigment characteristics (chlorophyll, carotenoids, and phycobilins). Pigments are considered natural food colorants, and pigments extracted from microalgae and cyanobacteria have emerged as an appealing source to replace synthetic coloring.