*2.3.1 Spirulina*

*Spirulina* (classified as *Arthrospira sp*) is a prokaryotic cyanobacterium that has been commercially produced for over 30 years for a variety of applications such as fish food, vitamin supplements, aquaculture, medicines, and nutraceuticals. *Spirulina*, by means of photosynthesis, converts sunlight into a lot of life essential nutrients (Fatty Acids, Carbohydrates, proteins, etc.). It is often regarded as a superfood and is widely farmed to fulfill current demand, particularly in specially built raceway ponds and photobioreactors.

*Spirulina* is one of the algae being researched for large-scale commercial cultivation. *Spirulina* has 60–70% protein by weight (containing several amino acids) and up to 10 times more beta-carotene per unit mass than carrots. *Spirulina* is high in B vitamins, phycocyanin, chlorophyll, vitamin E, omega-6 fatty acids, and minerals.

## *2.3.2 Chlorella*

*Chlorella* is a photoautotrophic, single-cell, spherical (2–10 m in diameter) green microalga with no flagella. It is simple to cultivate and produces massive amounts of biomass in a short period of time. It grows quickly and requires just CO2, water, sunshine, and a minimal quantity of minerals to thrive. They contain about 11–58% protein, 12–28% carbohydrate, and 2–46% lipids of its dry weight. Other composites include β-carotene, inositol, vitamin B6, vitamin B12, etc. *Chlorella* has been observed to lower cholesterol levels, decrease blood pressure, and even enhance the immune system.

## *2.3.3 Haematococcus*

*Haematococcus pluvialis* (*H. pluvialis*) is a unicellular freshwater green microalgae that is most known for being the major producer of Astaxanthin, a red pigment that has shown innovative anti-inflammatory and antioxidant applications in human

nutrition. It has also been recently observed to have preventive powers for diabetes and certain neurodegenerative diseases. The Astaxanthin levels of *H. pluvialis* are around 1.5–3% of its dry weight making it the largest known natural source of the same.
