The idea may sound disgusting, but experts take it seriously. Already sold in health-food stores as nutritional supplements, micro-organisms could help feed the world if prices came down.
Pay a visit to the University of Wageningen in the Netherlands, and you’ll come across a rather odd-looking farm. The crops are not sown in neat furrows, undulating gently in the wind. Instead, there are stacks of fat glass tubes filled with emerald fluid and shallow open-air ponds with green water.
Stranger still are the crops themselves: not plants, but single-celled creatures related to the organisms that form the green gunk you might scrape off your birdbath or swimming pool. And perhaps strangest of all, these little green cells, known as microalgae, could become routine additions to your dinner plate within the next decade or two.
“Instead of soybean protein, we will use algal protein,” predicts René Wijffels, a bioprocess engineer who founded the Wageningen facility, known as AlgaePARC, two years ago.
“Microalgae” is a loose term for a broad range of single-celled organisms, divided into two groups.
The first are true algae, eukaryotes with a nucleus.
The second, known somewhat confusingly as “blue-green algae”, are not algae but in fact cyanobacteria.
Microalgae may not sound very appetizing, but they are emerging as a way to help feed the world’s 7 billion people, who will be 9 billion by 2050. According to the Food and Agriculture Organisation (FAO), global food demand will jump 70 per cent by mid-century.
Although the world produces an overall surplus of food, one person in eight is undernourished because of economic and logistical barriers. With a limited amount of arable land available for growing conventional crops, how will the world tackle both current food poverty and future food security?
Step forward microalgae. These organisms have a cornucopia of hidden talents. Many of them can convert the sun’s energy into sugars and other molecules by photosynthesis – three times more efficiently than land plants. As a result, microalgae yields could far outstrip those of conventional crops and produce about 20 times more organic matter per hectare per year than soybeans.
Other types of microalgae could feed on the by-products of industry. And unlike plants, microalgae do not need arable land; they can be cultivated in seawater and in pools and bioreactors.
Certain microalgae are highly nutritious, packed with proteins, vitamins, oils and other nutrients. A cyanobacterium called Arthrospira (better known as Spirulina) contains 55-70 per cent protein, all the amino acids humans require, essential fatty acids and vitamins B, C, D and E. It is also a rich source of minerals.
Adding dried Spirulina to staple foods would be a simple way of giving a huge nutritional boost in developing countries, says Alessandro Lovatelli, a marine-seaweed specialist and Aquaculture Officer at the FAO. “The nutrient value of that dish would be much higher, without trying to change people’s eating habits.”
From Aztecs to Smarties
Humans have a long history of eating microalgae. The Aztecs, for example, ate Spirulina. In the 1960s and 1970s, growing demand from the health-food market prompted companies to begin producing microalgae on a commercial scale. By 2004 the global industry was producing 5,000 tonnes of microalgal products, with a turnover of about $1.25 billion.
Walk into a health-food shop today and you can already fill your basket with microalgae in the form of powdered supplements or as additions to such foods as pasta, bread and biscuits – not to mention blue Smarties, which owe their colour to a Spirulina extract.
A major obstacle to the expanded use of microalgae is their cost. According to Wijffels and his colleagues, the cost of oils and proteins made from microalgae would have to fall by a factor of 10 to become viable alternatives to today’s foods. As a result, microalgae remain a niche market for such “high value” products as health foods – too expensive for the poor and economically uncompetitive with conventional crops in the developed world.
Scientists concede that they still know very little about the organisms they are trying to grow. “In terms of farming them, we are really at the beginning,” says Brenda Parker, a biochemical engineer at the University of Cambridge and business-innovation officer at InCrops, an EU-funded project that helps bring green technologies to market.
With estimates of the number of different microalgal species in the tens of thousands, researchers say they have only begun to understand how they might be used. “The biggest challenge is moving the mindset away from cultivating just ‘algae’, treating them as all one thing,” says Parker. “They are remarkably diverse organisms with hugely different physiologies.”
What microalgae could make
Food (Proteins, carbohydrates, lipids, vitamins)
Replacements for petrochemicals
Bioremediation (Industrial and chemical cleaning)
Replacements for plant oils (E.g. for cosmetics, soaps etc.)
Too much sunlight
Microalgae are better photosynthesisers than land plants, reaching an efficiency of 3 per cent in current bioreactors. Double that and you slash production costs by 40 per cent, says Wijffels.
Paradoxically, one way to do this is to limit the amount of sunlight reaching the algae. Too much sunlight, even the rays on a normal sunny day, can stunt their growth.
So researchers are now experimenting with ways to reduce the sunlight reaching microalgae, for example by building bioreactors with vertically stacked tubes. They are also trying to minimise the amount of fresh water needed in microalgae farms, while sustainably sourcing and recycling the nutrients that microalgae need, such as nitrogen and phosphorus.
Another approach is to engineer the microalgae. Here cyanobacteria have a head start, as the technology to genetically engineer them already exists – to boost their photosynthesis, for example, or to enable them to secrete nutritional supplements. Eukaryotic microalgae are harder to engineer, but they can make and store large quantities of oils that are suitable as biodiesel.
Scientists are also developing microalgae as alternatives to conventional biofuel crops. They face similar technological and economic challenges, leading many to argue that food and biofuels should be developed together. “You have to benefit from multiple ingredients from microalgae, because only then can you make them cost effective,” says Wijffels.
This is one reason why Spirulina, despite its nutritional benefits, is unlikely to be grown on an industrial scale. It could, however, be a solution to the problem of feeding the rural poor, where the costs and logistics of food transport are the key issues, says Lovatelli.
Multinationals and governments
Although the widespread use of microalgae in human food is at least a decade away, large multinationals are beginning to take an interest. In September 2013 U.S. biotech company Solazyme announced that it had agreed to supply algal oil to Unilever, which uses such vegetable products as palm oil in its food and cosmetic products.
of dried cyanobacterial and microalgal products were sold globally in 2004 with an average market price of about €182/kg.
To compare this with conventional vegetable oil crops, the world production of palm oil, which is used in cosmetics and food, is around 40 million tonnes, with a market value of about €0.5/kg.
Governments, too, are investing in microalgae, both to develop the technology and to establish the economic and social policies needed to maximise its viability. Parker and her colleagues are involved in a four-year EU initiative called EnAlgae, which supports collaboration among academic researchers, companies and policymakers from countries in north-western Europe.
“There’s a strong economic benefit to integrating with other industries,” says Parker. She and her Cambridge team are testing the ability of a microalga called Phaeodactylum to scrub nitrate from wastewater produced by local water purification plants.
Phaeodactylum also produces oil containing an omega-3 fatty acid called EPA, which is important for human nutrition. “It’s a really nice synergy,” says Parker. Beyond their use in human food, microalgae will probably also see extensive use in animal and fish feed.
The final hurdle is consumer acceptance, but that is partly a matter of familiarity, says Lovatelli, who happily tucks into Spirulina. But there is a precedent: anyone who has eaten sushi will recognize microalgae’s relative, macroalgae – or seaweed. Give it a few years, and perhaps the idea of rolling up to the drive-thru in your algae-fuelled car to buy yourself an algae burger won’t seem so strange.
By Claire Ainsworth