Microalgae represent the most promising, sustainable and renewable source of plant-based nutrition for the planet’s population. The brief scientific review to follow shows the outstanding characteristics of Chlamydomonas reinhardtii, a super – superfood.
Chlamydomonas reinhardtii, the model alga
Studies on Chlamydomonas reinhardtii were initiated in the 19th century (Ehrenberg,1833; Dangeard, 1888). A unicellular alga, used as a model in numerous experimental studies on human genetics and pathology, plant biology and and photosynthesis, microbiology and biotechnology. (1)
In 2018, top algaculture experts-at the second edition of AlgaEurope, Europe’s largest summit dedicated to the sector-identified C. reinhardtii as one of the most promising species for use in food and feed production. Albeit in the knowledge that it faces the burden of its licensing as a novel food. (2,15)
Nutrients and micronutrients
Comparison of C. reinhardtii with the two most famous microalgae-Chlorella vulgaris and Artrhospira (Spirulina) platensis-reveals its great potential:
– protein in high amounts and carbohydrates, such as spirulina and chlorella,
– lipids. Omega 3 in line with the others, but in greater proportion than Omega 6. Higher content of α-linolenic acid,
– minerals. Presence of selenium, instead absent in the other two species, which is essential for antioxidant action,
– pigments. Higher concentration of total chlorophylls and carotenoids, themselves effective antioxidants
– Heavy metals. Lower tendency for accumulation of heavy metals, which can pose a health risk in assumptions of open-water cultivation (not also in photoreactors).
Chlamydomonas reinhardtii, microbiota and intestinal eubiosis
Following recognition as GRAS(Generally Regarded As Safe) by the U.S.Food & Drug Administration (FDA), Chlamydomonas reinhardtii was tested in vivo in a clinical study in humans in order to evaluate its effects on gastrointestinal health and microbiota.
The microalgae has demonstrated the ability to promote the eubiosis of the microbiota, reducing its imbalances and improving overall gut health. Even under conditions of colitis-induced stress. (4)
Fig. 1 and Fig. 2. Table of major microalgae species, relative macronutrient concentrations, and FDA GRAS recognition codes. (Fields et al., 2020). Comparison of the concentration of major fatty acids among 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 safety of Chlamydomonas reinhardtii (THN 6 strain) for human consumption was verified in vitro but also in vivo by administering its powder preparation to humans. Mutagenicity, cytotoxicity and other potential adverse effects were thus excluded. (5) Tests conducted on laying hens by adding the microalgae to the ration revealed additional beneficial effects in terms of increasing the concentration of lutein and zeaxanthin in eggs, without affecting animal health. (6)
The bioaccessibility of these carotenoids is much higher, comparing with Chlorella vulgaris, without requiring prior physical treatments (which are necessary for Chlorella). (7) Lutein and zeaxanthin are referred to as ‘retinal pigments’ because they are accumulated in the retina of the eye and help protect it from the damaging effects of blue light (e.g., ‘blue light. computers, TVs, smartphones). (8)
Fig. 4. Properties of lutein contained in Chlamydomonas reinhardtii (Saha et al., 2020)
Help against antibiotic resistance
Antibiotic resistance was described by WHO, in 2019, as the most serious threat to the health of the world’s population. Algae, including Chlamydomonas reinhardtii, have shown the ability to produce numerous metabolites (e.g., polyphenols, peptides, fatty acids, sterols, etc.). Which can even replace antibiotics (e.g., Algatan) due to their activity against numerous pathogenic microorganisms. (9)
Sulfurated polysaccharides are the most promising metabolites due to their ability to inhibit the formation and promote the elimination of bacterial biofilms. These allow bacteria to resist the action of antibiotics and increase their virulence in various foods (e.g., water, cheese, poultry, meat), as well as in hospital environments. (10)
Fig. 5. Algal metabolites with antibacterial action with different sites of action (Bhomwick et al., 2020)
Space and medical applications
Cultivation of the microalgae has been tested on theInternational Space Station(ISS), which is already equipped for Chlorella vulgaris. The oil produced from it could help mitigate the effects of microgravity and cosmic radiation, as well as provide significant amounts of nutrients. Its potential is also related to its lack of toxicity, although this is not yet officially recognized. (11)
The production of recombinant proteins for therapeutic use is another prerogative of C. reinhardtii, which can be used to make antibodies, vaccines, enzymes, and other drugs (e.g., “I’m not a drug”). insulin for diabetes. (12) In fact, microalgae has been 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 it turns out, are capable of producing numerous bioactive compounds with various actions including antifungal, antibacterial, and antiviral. The sulfur groups in them appear to be the agent responsible for specific antiviral actions, also capable of inhibiting the new coronavirus SARS-CoV-2.
Increased selenium supplementation , in particular, appears to be able to aid in the attenuation of RNA viruses through its ability to improve immunocompetence and reduce the frequency of their mutation. Since Covid-19 belongs to the category of RNA viruses, adequate selenium intake could be helpful in mitigating its pathological effects and reducing its mutations. (14)
Regulatory hurdles in EU
Applications of Chlamydomonas reinhardtii for food use have only been studied in recent years. Research to date, moreover, concurs both in ruling out any hypothesis of possible toxicity and in favorably evaluating the nutritional properties and health benefits associated with the inputs of this green microalgae.
Regulatory barriers to its use in the production of foods and food supplements to be released into the EU, however, are not insignificant. Although the microalgae is already recognized in the U.S. as safe for human consumption and its use can contribute to achieving at least three of the Sustainable Development Goals (SDGs), its authorization in the EU, however, postulates the submission of an onerous dossier to Brussels (15, 16).
Dario Dongo and Andrea Adelmo Della Penna
Notes
(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 capacity 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 a. (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) Calder (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 Ireland’s instance, the European Commission assessed evidence of EU consumption of Chlamydomonas reinhardtii before 15.5.97 as insufficient. Deducing the application of the Novel Food regulation (reg. EU 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.
