Microalgae Cultivation for Valuable Products

In aquatic areas, small photosynthetic organisms known as microalgae are common. Their capacity to create beneficial bioactive compounds is well established. As the market for sustainable and environmentally friendly products grows, microalgae production is becoming a significant area of study.

Introduction to Microalgae Cultivation

Open ponds or enclosed photobioreactors can both be used to grow microalgae. Depending on the type of microalgae and the desired results, the culture technique is chosen. While less expensive, open ponds are less productive and more prone to pollution. Photobioreactors, on the other hand, are more expensive and require more maintenance, but they offer higher productivity and better control over the culture conditions.

To cultivate microalgae, the following factors must be optimized:

• Light intensity and quality: Microalgae require a specific amount and quality of light for photosynthesis. The use of LED lights with specific wavelengths can improve microalgae cultivation.
• Temperature: The optimal temperature for microalgae growth varies depending on the species. A constant temperature can be maintained in closed photobioreactors.
• Nutrients: Microalgae require N, P, and micronutrients for growth. The production of bioactive substances can be improved through the use of nutrient-rich medium and nutrient concentration adjustment.
• pH: The pH of the culture medium has an impact on how well microalgae develop.
• CO₂: CO₂ is necessary for photosynthesis in microalgae. The CO₂ enriched air or flue gas can help microalgae growth.

Applications of Microalgae Cultivation

• Biofuels

Microalgae can be used to produce biodiesel, bioethanol, and biogas. Microalgae are more productive and do not compete with food crops for resources and land like traditional biofuel crops like corn and sugarcane do. Moreover, microalgae have more lipids, which can be turned into biodiesel. Although the study on microalgae for biofuel generation is still in its early stages, it has a lot of promise.

• Pharmaceuticals

Microalgae contain a variety of bioactive compounds such as pigments, fatty acids, and polysaccharides that have pharmaceutical properties.

1) Antioxidants

Microalgae are rich in antioxidants that protect cells from oxidative stress. For example, astaxanthin found in microalgae has antioxidant and anti-inflammatory properties and can be used as a dietary supplement.

2) Anti-Inflammatory Agents

Inflammation is a natural response of the body to injury or infection, but chronic inflammation can lead to a variety of diseases such as arthritis, cancer, and heart disease. Microalgae contain compounds such as omega-3 fatty acids, phycocyanin, and polysaccharides that have anti-inflammatory properties.

3) Antimicrobial Agents

Microalgae also can be used to produce natural antimicrobial agents. Microalgae species such as chlorella and spirulina have been found to exhibit antibacterial and antifungal activities. For example, bioactive compounds with antimicrobial activity produced by microalgae include polyunsaturated fatty acids (e.g. eicosapentaenoic acid and docosahexaenoic acid), peptides (e.g. microcystin), and terpenoids (e.g. farnesol).

• Nutraceuticals

Nutraceuticals are products that combine nutritional and pharmaceutical properties. Microalgae are a rich source of vitamins, minerals, and antioxidants.

1) Proteins

One excellent source of plant-based proteins is microalgae. They are a complete protein source since they have all nine essential amino acids. One of the most popular types of microalgae, Spirulina, has a protein content of up to 70% by weight.

2) Vitamins

Vitamin A, B1, B2, B3, B6, B9, C, D, and E are among the vitamins abundant in microalgae. Certain species, like Chlorella, are also excellent sources of vitamin B12, which is typically exclusively present in animal products.

3) Minerals

Minerals including iron, magnesium, calcium, potassium, and zinc are abundant in microalgae.

4) Fatty Acids

Omega-3 and omega-6 essential fatty acids are abundant in microalgae. Nannochloropsis and Schizochytrium are well known for having high omega-3 content.

• Bioremediation

Microalgae have the ability to absorb and remove pollutants such as heavy metals and organic compounds from contaminated water. This process is known as bioremediation and is an eco-friendly and sustainable way to clean up contaminated environments. Microalgae can also be used for wastewater treatment, reducing the need for costly and energy-intensive treatments.