Microalgae are unicellular, microscopic and photosynthetic microorganisms that grow in fresh or salt water. Most microalgae are eukaryotes; some still exist as prokaryotes.
There are about 800,000 species of microalgae that exist in different forms. There are distinct groups of microalgae, being the eukaryotic diatoms (Bacillariophyceae), green algae (Chlorophyceae) and golden algae (Chrysophyceae).
In addition, there are also the cynobacteria (Cyanophyceae or blue-green algae), which are prokaryotic organisms, although considered in the microalgae group. They are autotrophs, but some are heterotrophic organisms.
The most important phototrophic species are Arthospira (formerly Spirulina, blue-green algae), Chlorella, Dunaliella and Haematocussus. Microalgae are also cultivated for proteins, carbohydrates, lipids, micro-nutrients, food additives and cosmetic.
Microalgae as food and feed supplement:
The incorporation of microalgal biomass into feeds provide vitamins, essential amino acids, polysaccharides, mono- and n-3 and n-6 polyunsaturated fatty acids (MUFA and n-3 and n-6 PUFA, respectively), minerals, and pigments (such as carotenoids and chlorophylls).
There are various examples, for instance, concerning the utilization of Arthrospira, which comprise pet animals (dogs, cats and ornamental birds), horses and cattle feed.
In poultry feed, microalgae are viable as a partial replacement for conventional proteins and to enhance the yellow color of broiler skin and egg yolk. These are used for enhanching poultry growth and performance.
Microalgae as therapeutic agent:
The use of dried algal biomass and algal-derived biologically active compounds as pharmaceuticals has increased recently. Polysaccharides from microalgae are potent immunomodulatory, anti-inflammatory, hypocholesterolemic, hypolipidemic and hypoglycemic agents.
Biologically active compounds derived from different species of microalgae have been shown to possess several pharmacological properties such as anticoagulant, anti-inflammatory, anticancer, antimicrobial, antioxidant and antiviral activities.
Some commonly used microalgae:
Spirulina:
Spirulina (SP), a blue–green alga, is popularly used as a nutritional supplement as well as in therapeutic applications. Spirulina contains proteins, lipids, carbohydrates, some vital minerals, vitamins including β-carotene and a pigmented protein, C-phycocyanin.
The antioxidant potential of Spirulina was demonstrated in both in vitro and in vivo studies. Spirulina is known for its wide-ranging biological activities and antioxidative, anti-inflammatory, antimutagenic, antiviral, immune enhancing, cardioprotective and anticancer properties.
Spirulina can prevent or inhibit cancers in animals. Spirulina is a powerful stimulant for the immune system as it increases the phagocytic and natural killer cells activities. Spirulina has a protective effect against many toxicants including mycotoxins.
Chlorella:
Chlorella vulgaris is a green unicellular microalgae with biological and pharmacological properties important for human health. C. vulgaris is use as a food source.
Contains a unique and diverse composition of functional macro- and micro-nutrients including proteins, omega-3 polyunsaturated fatty acids, polysaccharides, vitamins and minerals.
Supplementation with C. vulgaris can ameliorate hyperlipidemia and hyperglycemia, and protect against oxidative stress, cancer and chronic obstructive pulmonary disease.
Dunaliella:
Dunaliella salina is a unicellular marine phytoplankton that belongs to the phylum Chlorophyta. Dunaliella is a unique species of microalgae that has evolved to live in extreme environmental conditions comprising a major constituent of all natural hypersaline environments.
Dunaliella is one of the richest natural producers of carotenoid, producing up to 15% of its dry weight under suitable conditions. The potential ability of carotenoids is to act as antioxidants, immunomodulatory agents and prevention of cancers.
Therefore, D. salina used as a source of antioxidant to improves frees radical scavenging activities in the body and protect cells from oxidative damage.
Conclusion:
Based on these properties, microalgae are considered as alternative to achieve the foods of high quality with therapeutic properties not only in humans but also in animals with low environmental impact because they can be cultivated in non-cultivated lands. The cultivation of microalgae in the future will also help to combat with the food security problems.
Authors: Sana Majeed *1, Aisha Khatoon1, Zain- Ul- Abidin2, Ashiq Ali1, Aneela Amin1, Muhammad Yasir Nawaz1.
1 Department of Pathology, Faculty of Veterinary Science, University of Agriculture Faisalabad, Pakistan. 2 Veterinary Research Institute, Lahore, Pakistan.
* Corresponding Author Email: sanamajeed243@gmail.com