New Roles for an Ancient Microplant —

Green algae have existed on Earth for billions of years, but surprisingly it was only in 1890 that chlorella was first described for science by the Dutch microbiologist Martinus Beijerinck, who found Chlorella vulgaris in lake water. This microphyte (microscopic plant) that lives floating in water was later domesticated by human­kind, beginning its fantastic journey towards being identified as a superfood. It has been seen as a substitute food resource in a world threatened by food shortages, a nutritionally complete health food, an ingredient for foods for astronauts, and a possible future replacement for fish protein. Besides producing vegan algae oils (omega-3 fatty acids such as DHA and EPA), green algae are currently being used to make algal biofuels, algae batteries, edible packaging materials, and even energy-generating facades for buildings. These multiple uses indicate that the microscopic aquatic green algae that have played an important role in the evolution of life on Earth are also highly valuable to humankind for the present and future.

A true hidden champion

Cultivation of green algae in Taiwan began in the 1960s, and later, with the help of technical assistance from Japan, Taiwan became a major exporter of chlorella. At its peak, more than 30 companies were mass-­producing chlorella in Taiwan, providing 90% of the global supply, and even in 2006, 80% of the world’s chlorella was being exported from Taiwan. Today, after six decades of change in the industry, the main exporting countries are Taiwan, China, Germany, Japan, and India. According to statistics released in March of 2023 by the Department of Industrial Technology of the Ministry of Economic Affairs, Taiwan’s exports of green algae in 2022 totaled 928.56 metric tons, accounting for 45.05% of the global total, meaning that Taiwan has the highest market share in the world. Meanwhile, figures published by the China Grain Products Research and Development Institute indicate that in 2021 the total value of chlorella production in Taiwan was some NT$700 million.

At present Taiwan has five or six companies mass-­producing green algae, of which the longest-established is the Taiwan Chlorella Manufacturing Company (TCMC), founded in 1964. When TCMC first started out, they recruited Dr. Yoshiro Takechi, director of the Tokugawa Institute for Biological Research in Japan, to come to Taiwan to assist them in selecting chlorella strains and in improving their clean culturing technology. “Although Japanese scientists had long known about the nutritional value of chlorella and had conducted many years of research into its cultivation, Japan’s colder climate made it difficult to culture green algae and impossible to do so year-round. When they discovered Taiwan’s abundant sunlight, favorable climate, and easy access to pure unpolluted water, they knew they had found a place well-suited to cultivating chlorella,” says Helena Song, research and development manager at TCMC. In the early days, all the chlorella produced by TCMC was exported to Japan, because Japan already had a well-developed market for the product and many people were aware of the benefits of consuming it. Later, as chlorella evolved into a global superfood, consumers in many countries recognized the high quality of the green algae produced in Taiwan and its rigorous food safety standards as well as the ideal and pristine culturing environment, and currently you can find Taiwanese chlorella products in more than 30 countries.

Chlorella has a diameter of only two to eight microns, and to clearly see the process of cell division one needs a microscope with a magnification of at least 600x.

It all starts in the laboratory

“At the beginning, chlorella is cultured as a group of cells in a petri dish in the laboratory, where they require light 24 hours a day and a temperature of 4°C. Within two weeks, a single cell will divide again and again to make more than a billion cells,” says Song. The green algae that is sold on the market as a health food is mainly made up of microscopic chlorella with a cell diameter of only two to eight microns. A microscope of at least 600x magnification is needed to clearly see the individual chlorella cells and the process of cell division. To observe the organelles within the cells requires about 1,000x magnification.

Chlorella needs to be continually transferred between different containers during the culturing process, from a petri dish to a test tube and then to small and large flasks, until after 21 days it is transferred into an outdoor pond for continued cultivation. These outdoor ponds are very shallow (only some 35–45 centimeters deep) to enable all the algal cells to be exposed to sunlight so that they can conduct photosynthesis. To help achieve this, the water in the ponds is continuously churned by mechanical arms. The largest ponds are 45 meters in diameter, and by this point in the production process the number of individual algal cells in a pond this size has reached some 2.4 quadrillion.

Harvesting of the chlorella can begin after eight weeks, at which time the water is filtered out and impurities removed using centrifugal separators. Then the algae are dehydrated at 300°C, crushed into a powder, and made into tablets or capsules. “These days every­body basically uses the same steps in the cultivation of ­chlorella, but we have extra quality control requirements. At ­regular times each year we send samples to the Japan Food Research ­Laboratories for testing to confirm that there is no contamination with metals or other impurities,” Song states.

In its early years the Taiwan Chlorella Manufacturing Company, founded in 1964, sold all of its products to Japan. Today chlorella is seen as a superfood, and you can buy TCMC products in more than 30 countries. (courtesy of TCMC)

Chlorella is considered a superfood, and it offers the highest content of protein, nucleic acids, chlorophyll, and vitamin B12 of any organism in the plant kingdom. (courtesy of TCMC)

Comprehensive nutritional value

Green algae are aquatic plants which, like terrestrial plants, also perform photosynthesis, so they contain similar nutrients. Chlorella is noted for its high protein content, which accounts for 60% of chlorella cells by dry weight. Comparing 100 grams of chlorella to the same amount of powdered milk, astonishingly the former contains 20 times as much protein as the latter. This is why, during the postwar baby boom of the 1950s, when rapid population growth was putting a strain on food supplies, researchers in countries including the US, the UK, France, and the USSR studied chlorella in hopes that it could become a supplementary source of protein. Professor Hiroshi Tamiya, a botanist at the University of Tokyo, joined in this research and later conducted a project on mass production of green algae at the Tokugawa Institute for Biological Research, where in 1957 he established a green algae research center and began working toward the commercialization of these products.

However, chlorella cell walls are very thick, with three membrane layers, so that if chlorella is eaten in its natural state it cannot be digested and absorbed by the human body. “We acquired patented German technology that uses high pressure to burst open the cell walls so that they can be digested, just like popping open corn kernels when making popcorn,” explains Song.

 

Chlorella cells are first cultured in the laboratory in petri dishes, test tubes, and then small and large flasks, and are finally moved to outdoor ponds to continue photosynthesis. After the algae are harvested, the water is filtered out and impurities removed using centrifugal separators. Then the chlorella is dehydrated at 300°C, pulverized, and made into pills or capsules.

Chlorella is made into easily ingestible health food supplements that are sold around the world.

Not to be underestimated

As well as conducting R&D on the use of chlorella as a health food, TCMC has also actively worked with academia in hopes of developing other beneficial applications for green algae. Major projects have included collaborative research in the early days with Professor Iwao Umezawa of Japan’s Kitasato Institute, to investigate the possible anti-infective and anti-­cancer properties of an acidic polysaccharide, Chlon A, that is found in chlorella; a 1980 study on the effects of chlorella on serum cholesterol levels in rats, conducted with Chung Shan Medical University Hospital and National Taiwan University Hospital; a 2008 study on the ability of peptides in chlorella to lower blood pressure, done with the Department of Food Science at National Taiwan Ocean University; and a 2018 study of the effects of chlorella supplementation on muscle damage in athletes induced by resistance exercise, in collaboration with Taipei Medical University.

Among this research, one especially interesting study was done in 2009. Back in 1998, Taiwan had experienced a widespread outbreak of enterovirus among children. At that time there was no specific medicine to treat entero­virus, leading to public alarm. Wu Chang-jer, ­distinguished professor and chair of the Department of Food Science at National Taiwan Ocean University, recalls: “Enterovirus 71 has no cell membrane, so ethanol was ineffective, and the only thing we could use to kill the virus was bleach. However, this was very harmful to young children.” In 2009 Wu was commissioned by TCMC to do a study and discovered that polysaccharide extracts from sea lettuce (Ulva lactula) can inhibit infection with Enterovirus 71, a finding which once again drew widespread attention to green algae.

Research suggests that large-scale farming of seaweed can relieve pressure on terrestrial farmland. The photo below shows (left) Sargassum hemiphyllum, a seaweed with farming potential, and (right) polysaccharides extracted from this seaweed.

Wu Chang-jer believes that as an island nation Taiwan has the potential to develop seaweed cultivation, and in the future to develop means to sequester carbon in the ocean. This would be an ideal model for the use of Taiwan’s marine environment.

The future of chlorella

In the 1970s, as part of its flourishing space program, the US National Aeronautics and Space Administration took chlorella into space to test its potential as a food source, for generating oxygen by photosynthesis, and for treating human waste. At that time environmental engineers in the US who were using green algae in wastewater treatment realized that the methane produced by fermentation of effluent might make an excellent source of renewable energy, inspiring many further studies by a variety of stakeholders. Furthermore, with the increasing global population continuing to present a danger of food shortages, a research team at the University of Queensland in Australia has calculated that if enough seaweed farms could be developed in the ocean by 2050 to supply 10% of human food, this could offset the shortfall in food production from the world’s 110 million hectares of cultivated land. However, the protein content of seaweed is only some 30%, so some people believe that chlorella, with a protein content of 60%, could play a critical role in providing adequate protein.

Green algae are among the most ancient living things on Earth, and are regarded as the primogenitors of terrestrial plants. Although they occupy a place at the very bottom of the Earth’s food chain, they could also be the foundation for solutions to some of the planet’s problems. Taiwan’s chlorella industry has been going strong for 60 years now, and its future potential seems boundless.

Scholars note that seagrasses (flowering plants that grow in marine environments) can store twice as much carbon per square kilometer as terrestrial forest. Meanwhile the microalga Haematococcus pluvialis is 21 times as effective in carbon sequestration as tree planting, and offers highly promising research avenues.