Microalgae
Nannochloropsis sp.
Nannochloropsis spp. are microalgae living in freshwater and seawater. Nannochloropsis species have been used for several decades to produce nutraceuticals and feed supplements.
Nannochloropsis is suitable for cultivation in photobioreactors (PBRs) rather than polyethylene bags and suitable to produce high-density mono-specific cultures in a liquid medium, kept under agitation by insufflating filtered air enriched with CO2 to support photosynthesis. The culture medium consists of sterile seawater supplemented with mineral micronutrients, whereas hazardous chemicals, such as antibiotics or pesticides, are avoided.
The chemical composition of Nannochloropsis biomass can show quantitative variations depending on the microalga strain and environmental conditions. Type of PBR, quality and quantity of light, temperature, and composition of the culture medium are among the main factors affecting the chemical composition of the algal biomass.
Chlorela
Chlorella is widely cultivated on an industrial commercial scale in several countries for the production of biomass and derivative products. The interest in these microalgae is due to their rapid growth and simple life cycles, enabling use as a food substitute due to their high protein, carotenoids, vitamin, and mineral content. In this way, Chlorella has been extensively studied to obtain biomass or to extract bioactive compounds with potential applications in functional food supplements, as well as nutraceuticals, cosmetics, and pharmaceuticals. This advantage for human and clinical nutrition is due to their biological functions with health benefits. Several studies of the bioactive compounds of microalgae have shown that these compounds may have beneficial biological activities, not limited to antitumor, anti-inflammatory, antimicrobial, antioxidant, and anticoagulant properties. In this way, Chlorella can become a source of bioactive compounds or even be able to be applied as a functional food promoting the prospect of sustainable health benefits.
Haematococcus pluvialis
Haematococcus pluvialis is a freshwater green microalga and the richest source of natural astaxanthin, which has significant applications in the nutraceuticals, cosmetics, food, and aquaculture industries. Astaxanthin known as reducing free radicals and oxidative stress and helps the human body maintain a healthy state. Hence it is one of the high-value microalgal products of the future. In fact, the astaxanthin is a protection mechanism of the micralgae from stressful environmental conditions like high tempratures, salinity and more. Astaxanthin enables the microalga to maintain its DNA undamaged, ready to grow again when the conditions are favorable. This extraordinary ability exemplifies astaxanthin’s role as a powerful antioxidant. Natural astaxanthin generated from microalgae has been found in experiments to be over 500 times stronger and far more effective than any other carotenoids.
Porphyridium cruentum
The microalgae Porphyridium cruentum is well-known for its capacity to produce a diverse range of high-value compounds, including sulfated polysaccharides, pigments, poly-unsaturated fatty acids (PUFAs), and phycobiliproteins. Freshwater, brackish, and marine conditions have all been shown to support Porphyridium cruentum.The extracellular matrix of Porphyridium cruentum biomass can include up to 40% polysaccharides. Exopolysaccharides (EPS) protect cells from external stress and produce carbon skeletons during periods of hunger, and they have shown considerable promise in aesthetic, nutraceutical, pharmacological, and industrial uses.
Dunaliella salina
Dunaliella salina is a unicellular microalga that thrives in high temperature, salty environments. This green alga is known as a halophile, or “salt-lover,” since it can survive a relatively limited range of salinity in its environment. Dunaliella Salina boosts abscisic acid metabolism and increases glycerol formation in response to the stress of bright sunshine and widely fluctuating salt levels, according to studies, mechanisms that assist prevent the cell membrane from losing water across a high osmotic gradient. Dunaliella salina similarly stores large amounts of beta-carotene and photolyase in order to protect itself from UV rays.
Commercially, this alga is grown in lagoons (low-tech) and at high-cell densities under well controlled conditions (high-tech). Dunaliella’s high carotenoid content is the main property that makes it a popular nutritional supplement. The antioxidant action of carotenoids is well recognized. Dunaliella includes 9-cis-carotene, a kind of beta-carotene that has been shown in studies to have much higher antioxidant activity and DNA repair than other forms of beta-carotene. Preliminary research in mice suggests that 9-cis-carotene may be able to prevent atherosclerosis and fatty liver disease in humans. Vitamins, minerals, lipids, proteins, carbohydrates, and chlorophyll are all found in Dunaliella.
Spirulina
Spirulina is a multicellular, filamentous blue-green microalgae with symbiotic bacteria that fix nitrogen from the atmosphere. The multicellular cylindrical trichomes are arranged in an open left-hand helix along the whole length, making it easily identifiable. The transverse cross-walls of the blue-green non heterocystous filaments, which are made up of vegetative cells that undergo binary fission in a single plane, are plainly visible.
Spirulina microalgae is a good source of high-quality protein, iron, gamma-linolenic fatty acid, carotenoids, and vitamins B1 and B2. Despite the fact that Spirulina chemical composition varies greatly when cultivated in open reservoirs, its efficacy as a supplement in the treatment and prevention of many diseases has been demonstrated in a number of experimental and clinical investigations. Spirulina biomass may be supplemented with trace elements such as iron, iodine, selenium, zinc, copper, manganese, and chromium in high bioavailable form during cultivation in open reservoirs and notably in closed photobioreactors. The biomass in question is being evaluated as a component of novel bioactive food additives.