Microalgae are positioning themselves as an invaluable source of various raw materials, among which pigments stand out. These colorful compounds not only add beauty to our environment but also possess exceptional biological properties with applications in food, cosmetics, pharmaceuticals, and other industries.
Although their complete biomass has traditionally been utilized, current research focuses on the extraction of specific components, notably pigments. Scientists from the Universidad del Mar and the National Autonomous University of Mexico published a scientific review in the World Journal of Microbiology and Biotechnology, detailing the main strategies adopted over the last decade, including light adjustments and the characteristics of the mineral medium to further enhance the pigment contents of microalgae during autotrophic cultivation.
Microalgal Biomass: A Versatile Resource
Initially, total biomass was the main product obtained from microalgae. While it remains relevant in terms of volume and economic value, with applications in human nutrition, animal feed, and fertilizers, its potential has expanded thanks to biorefinery. This process allows for the extraction of specific industrial derivatives such as lipids, carbohydrates, proteins, and pigments.
Among these derivatives, pigments stand out for their high added value and wide range of applications, from natural food colorants to cosmetic and pharmaceutical components. Additionally, microalgal pigments often exhibit greater antioxidant bioactivity than those of plant origin, making them a healthier alternative to synthetic ones.
Types of Pigments in Microalgae
Microalgal pigments are classified into four main groups: chlorophylls, carotenoids, phycobiliproteins, and polyphenols. Each plays specific roles within the cell and possesses unique chemical characteristics.
- Chlorophylls: These pigments are essential for photosynthesis, the process by which microalgae convert solar energy into chemical energy. Chlorophyll a is the primary pigment in most photosynthetic organisms, although exceptions like chlorophyll d exist in certain cyanobacteria.
- Carotenoids: Besides participating in photosynthesis, carotenoids serve protective functions against oxidative stress. They are notable for their intense coloration and antioxidant properties, making them valuable ingredients in the food, cosmetic, and pharmaceutical industries.
- Phycobiliproteins: These pigments, exclusive to cyanobacteria and some red algae, are responsible for the blue and red coloration of these organisms. In addition to their photosynthetic function, they exhibit fluorescent properties with applications in biotechnology.
- Polyphenols: Although traditionally associated with terrestrial plants, these compounds are also found in some microalgae. They are known for their potent antioxidant activity and potential as natural colorants.
Applications of Microalgal Pigments
Beyond their aesthetic function, microalgal pigments possess remarkable bioactive properties. They act as nutraceuticals and pharmaceutical agents, contributing to human well-being. It is important to note that each pigment, with its unique chemical structure, performs specific biological functions.
Microalgal pigments are organic molecules with a chromophore characterized by long chains or closed rings of conjugated carbon double bonds, capable of absorbing specific regions of the visible spectrum.
Microalgal pigments offer a wide range of commercial applications:
- Food industry: As natural colorants, substitutes for artificial additives.
- Health: For their antioxidant and anti-inflammatory properties, as nutritional supplements.
- Cosmetics: As active ingredients in anti-aging products and sunscreens.
- Pharmaceuticals: As a basis for developing new drugs.
- Biotechnology: As fluorescent markers and biosensors.
Microalgae Stars of Pigmentation
Among the diversity of microalgae, four groups stand out for their richness in high-value-added pigments: cyanobacteria, rhodophytes, chlorophytes, and heterokontophytes. Some species within these groups accumulate significant amounts of particular pigments.
Optimizing Pigment Production
To increase pigment production in microalgae cultures, researchers have explored various strategies over the past decade. Manipulation of light, both in quantity and quality, as well as the duration of the photoperiod cycle, has proven effective. Similarly, the composition of the culture medium, including salinity, nutrient concentration, and the presence of inducing substances, influences pigment synthesis.
An interesting aspect is that, unlike pigments related to photosynthesis, the accumulation of polyphenols and secondary carotenoids usually requires stress conditions. This observation opens new perspectives for optimizing cultures.
The study highlights that to maximize pigment yield in microalgae cultures, various strategies have been developed:
- Light manipulation: Adjusting the intensity and quality of light influences pigment synthesis.
- Nutrient control: Inducing nutritional stress conditions can stimulate the production of certain pigments.
- Salinity: Some pigments accumulate in response to high salt concentrations.
- Inducing agents: Adding chemical substances can promote the synthesis of specific pigments.
- Nanoparticles and magnetic fields: Emerging technologies with the potential to increase pigment production.
Cutting-Edge Technologies for Pigment Enrichment
Two innovative technologies are revolutionizing microalgal pigment production: the application of metal nanoparticles and the use of magnetic fields. These approaches offer promising possibilities to increase the levels of commercially interesting pigments.
Conclusion
Microalgae represent a sustainable and versatile source of natural pigments with multiple applications. Understanding the factors influencing the production of these compounds is crucial for developing efficient cultivation strategies and optimizing their extraction. The future of the pigment industry looks bright, thanks to scientific and technological advancements in this field.
The study was funded by the DGAPA UNAM project.
Contact
Aitor Aizpuru
Universidad del Mar, Campus Puerto Ángel
San Pedro Pochutla, 70902, Oaxaca, México
Email: aitor@angel.umar.mx
Armando González-Sánchez
Instituto de Ingeniería, Universidad Nacional Autónoma de México
Ciudad Universitaria, Circuito Escolar, 04510, Mexico City, Mexico
Email: agonzalezs@iingen.unam.mx
Reference (open access)
Aizpuru, A., González-Sánchez, A. Traditional and new trend strategies to enhance pigment contents in microalgae. World J Microbiol Biotechnol 40, 272 (2024). https://doi.org/10.1007/s11274-024-04070-3
