Microalgae represent the most promising, sustainable and renewable source of plant-based nutrition for the planet’s population. The brief scientific review that follows shows the exceptional characteristics of the Chlamydomonas reinhardtii, a super – superfoods.
Chlamydomonas reinhardtii, the model algae
In the nineteenth century (Ehrenberg, 1833; Dangeard, 1888) studies on Chlamydomonas reinhardtii. A single-celled alga, used as a model in numerous experimental studies on human genetics and pathologies, plant biology and photosynthesis, microbiology and biotechnology. (1)
In 2018 the top experts of algaculture – at the second edition of AlgaEurope, the largest European summit dedicated to the sector – have identified C. reinhardtii as one of the most promising species to be used in food and feed production. Albeit in the awareness of having to face the burden of its authorization as novel foods. (2,15)
Nutrients and micronutrients
The comparison di C. reinhardtii with the two most famous microalgae – chlorella vulgaris e Arthrospira (Spirulina) platensis – reveals its great potential:
– proteins in high quantities and carbohydrates, such as spirulina and chlorella,
– lipids. Omega 3 in line with the others, but higher than the Omega 6. Higher content of α-linolenic acid,
– minerals. Presence of selenium, instead absent in the other two species, essential for the antioxidant action,
– pigments. Greater concentration of total chlorophylls and carotenoids, in turn effective antioxidants
– heavy metals. Less tendency to accumulate heavy metals, which can pose a health risk in the hypothesis of cultivation in open water (not also in photoreactors).
Chlamydomonas reinhardtii, microbiota and intestinal eubiosis
Following of recognition as GRAS (Generally Regarded As Safe) by the FDA (Food & Drug Administration, USA), Chlamydomonas reinhardtii was tested in vivo in a human clinical study to evaluate its effects on gastrointestinal health and microbiota.
The microalgae has demonstrated the ability to promote eubiosis of the microbiota, reducing imbalances and improving the general health conditions of the intestine. Even in conditions of induced colitis stress. (4)
Fig. 1 and Fig. 2. Table of the main microalgae species, relative macronutrient concentrations and FDA GRAS recognition codes. (Fields et al., 2020). Comparison between the concentration of the main fatty acids between Chlamydomonas reinhardtii, Chlorella and Spirulina (Darwish et al. 2020)
Fig 3. Chlamydomonas reinhardtii powder and sensory analysis (Fields et al., 2020)
Safety, bioavailability of carotenoids
The security di Chlamydomonas reinhardtii (strain THN 6) for human consumption has been verified vitro but also in vivo, by administering a powdered preparation to humans. Mutagenicity, cytotoxicity and other potential adverse effects were thus excluded. (5) The tests carried out on laying hens, by adding the microalgae to the ration, revealed further beneficial effects in terms of increasing the concentration of lutein and zeaxanthin in eggs, without affecting the health of the animals. (6)
Bioaccessibility of these carotenoids is much higher, in comparison with chlorella vulgaris, without requiring preliminary physical treatments (instead necessary for Chlorella). (7) Lutein and zeaxanthin are termed ‘retinal pigments’, as they accumulate in the retina of the eye and help protect it from the damaging effects of blue light (e.g. computer, TV, smartphone). (8)
Fig 4. Properties of lutein contained in Chlamydomonas reinhardtii (Saha et al., 2020)
Help against antibiotic resistance
Antibiotic resistance has been described by WHO, in 2019, as the greatest threat to the health of the world population. Algae, including Chlamydomonas reinhardtii, have shown the ability to produce numerous metabolites (eg. polyphenols, peptides, fatty acids, sterols, etc.). Which can even replace antibiotics (eg Algatan), thanks to their contrasting activity against numerous pathogenic microorganisms. (9)
The sulfurized polysaccharides they are the most promising metabolites, thanks to their ability to inhibit formation and promote the elimination of bacterial biofilms. The latter allow bacteria to resist the action of antibiotics and increase their virulence in various foods (eg water, cheese, poultry, meat), as well as in hospitals. (10)
Fig. 5. Algal metabolites with antibacterial action with different sites of action (Bhomwick et al., 2020)
Space and medical applications
Oats microalgae was tested in the International Space Station (International Space Station, ISS), already equipped for chlorella vulgaris. The oil it produces could help mitigate the effects of microgravity and cosmic radiation, as well as providing significant amounts of nutrients. Its potential is also linked to its absence of toxicity, although it is not yet officially recognized. (11)
Production of recombinant proteins for therapeutic use is another prerogative of C. reinhardtii, which can be used to obtain antibodies, vaccines, enzymes and other drugs (eg insulin for diabetes. (12) The microalga has in fact shown to meet the essential requirements for these purposes in terms of yield, productivity, versatility and safety. (13)
Microalgae and Covid-19
Some algae and microalgae, as seen, are capable of producing numerous bioactive compounds with various actions including antifungal, antibacterial and antiviral ones. The sulfur groups present in them seem to be the agent responsible for specific antiviral actions, also capable of inhibiting the new SARS-CoV-2 coronavirus.
The greatest integration of selenium, in particular, seems to be able to help attenuate RNA viruses, thanks to its ability to improve immunocompetence and reduce the frequency of their mutation. Since Covid-19 belongs to the category of RNA viruses, an adequate intake of selenium could be useful in mitigating its pathological effects and reducing its mutations. (14)
Regulatory barriers in the EU
Applications di Chlamydomonas reinhardtii for food use have only been studied in recent years. The research carried out so far is moreover in agreement both in excluding any hypothesis of possible toxicity, and in favorably evaluating the nutritional properties and health benefits associated with the contributions of this green microalgae.
The regulatory obstacles however, its use in the production of food and food supplements to be introduced into the EU is of no small importance. Although the microalgae is already recognized in the US as safe for human consumption and its use can help reach at least three of the Sustainable Development Goals (SDGs), its authorization in the EU however requires the presentation of a fee in Brussels dossier (15, 16).
Dario Dongo and Andrea Adelmo Della Penna
Footnotes
(1) Sasso et al. (2018). From molecular manipulation of domesticated Chlamydomonas reinhardtii to survival in nature. eLife 7: e39233, https://doi.org/10.7554/eLife.39233
(2) Eakpetch et al. (2018) Microalgae (Chalmydomonas reinhardtii) as novel food and feed ingredient: an impact of media manipulation strategy on biomass nutritional profiles. Conference AlgaEurope 2018
(3) Darwish et al. (2020) Chlamydomonas reinhardtii is a potential food supplement with the ability to outperform Chlorella and Spirulina. Applied Sciences 10: 6736, doi: 10.3390 / app10196736
(4) Fields et al. (2020) Effects of the microalgae Chlamydomonas on gastrointestinal health. Journal of Functional Foods 65: 103738, https://doi.org/10.1016/j.jff.2019.103738
(5) Murbach et al. (2018) A toxicological evaluation of Chlamydomonas reinhardtii, a green algae. International Journal of Toxicology 37 (1): 53-62, doi: 10.1177 / 1091581817746109
(6) Baek et al. (2018) Photoautotrophic production of macular pigment in a Chlamydomonas reinhardtii strain generated by using DNA-free CRISPR-Ca9 RNP-mediated mutagenesis. Biotechnology and Bioengineering 115 (3): 719-728, https://doi.org/10.1002/bit.26499
(7) Gille et al. (2016) Bioaccessibility of carotenoids from Chlorella vulgaris and Chlamydomonas reinhardtii. International Journal of Food Sciences and Nutrition 67 (5): 507-513, https://doi.org/10.1080/09637486.2016.1181158
(8) Saha et al. (2020) Marine microalgae for potential lutein production. Applied Sciences 10: 6457, doi: 10.3390 / app10186457
(9) Bhowmick et al. (2020) Algal metabolites: An inevitable substitute for antibiotics. Biotechnology Advances 43: 107571, https://doi.org/10.1016/j.biotechadv.2020.107571
(10) Vishwakarma et al. (2019) Evaluating the antibacterial and antibiofilm potential of sulphated polysaccharides extracted from green algae Chlamydomonas reinhardtii. Journal of Applied Microbiology 127: 1004-1017, doi: 10.1111 / jam.14364
(11) Zhang et al. (2020) Competitive growth assay of mutagenized Chlamydomonas reinhardtii compatible with the International Space Station veggie plant growth chamber. Frontiers in Plant Science 11: 631, doi: 10.3389 / fpls.2020.00631
(12) Levasseur et al. (2020) A review of high value-added molecules production by microalgae in light of the classification. Biotechnology Advances 41: 107545, https://doi.org/10.1016/j.biotechadv.2020.107545
(13) Rasala et al. (2010) The microalga Chlamydomonas reinhardtii as a platform for the production of human protein therapeutics. Bioengineered Bugs 2 (1): 50-54, doi: 10.4161 / bbug.2.1.13423
(14) Calders (2020) Nutrition, immunity and COVID-19. BMJ Nutrition, Prevention & Health 3 (1): 74-92, doi: 10.1136 / bmjnph-2020-000085
(15) # SDG2, End Hunger. # SDG3, Ensure healthy lives and promote well-being for all at all ages. # SDg12, Sustainable Consumption and production
(16) At the request of Ireland, the European Commission assessed evidence of consumption in the EU of Chlamydomonas reinhardtii before 15.5.97. By deducting the application of the regulation novel food (EU reg. 2015/2283). V. https://ec.europa.eu/food/safety/novel_food/catalogue/search/public/?event=home&seqfce=990&ascii=C
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE – GIFT – Food Times) and Égalité.
Graduated in Food Technologies and Biotechnologies, qualified food technologist, he follows the research and development area. With particular regard to European research projects (in Horizon 2020, PRIMA) where the FARE division of WIISE Srl, a benefit company, participates.