Gifts from the Seaweed

Toothpaste, salad dressing, sushi, and NU's own super nori.


By Donald Cheney

“Seaweeds? You study seaweeds? What on earth for?” That’s the typical response I get whenever I tell someone what I do for a living.

By and large, people don’t have a very good impression of seaweeds. They think they’re just some stinking, slimy nuisance that washes up on clean sandy beaches. Most people don’t realize how important seaweeds are, both ecologically and commercially. In reality, seaweeds are crucial primary producers in oceanic food webs. They’re also valuable sources of food, micronutrients, and products for the pharmaceutical industry.

Taxonomically, seaweeds are known as macroscopic marine algae, which are generally more ancient and less complex than higher plants. Yet seaweeds are as highly evolved and well adapted to their water environment as higher plants are to their land environment.

Underwater, in their natural habitat, seaweeds are very beautiful. They range widely in color (red, green, brown, purple) and size (some as tall as oak trees). To fully appreciate their beauty, of course, you have to see them underwater, moving gracefully back and forth with the flow of wave motion and currents.

This flexibility, an important adaptation to the marine environment, reflects the major biochemical difference between seaweeds and higher plants: the unique composition of a seaweed’s cell walls.

The cell wall of a land plant consists primarily of a polysaccharide called cellulose, a major component in wood, which provides a rigid structure. The cell wall of a seaweed consists primarily of polysaccharides called phycocolloids. Common examples of phycocolloids include carrageenan, agar, and agarose, which are extracted from red seaweeds for use as gelling and thickening agents in literally hundreds of food and pharmaceutical products.

Carrageenan, for example, is used in toothpaste, salad dressings, ice cream, processed cheeses, and other dairy products. Agar is used to make gel capsules and gels used for culturing bacteria. Agarose is used for separating DNA fragments.

Interestingly, the phycocolloid industry, which is currently estimated at over $250 million annually, started right here in Massachusetts in the 1930s. It began with the extraction of carrageenan from the red seaweed Chondrus crispus, known locally as Irish moss. Even before the 1930s, Irish moss was harvested in Duxbury and Kingston, dried on beaches, and used by local microbreweries to filter beer (a use it still enjoys today).

A lot has changed in the seaweed industry. Now seaweeds aren’t harvested from the wild; they are farmed, or aquacultured, on lines and nets. And, just as in land agriculture, plant breeding, or strain improvement, is an important—if not crucial—part of the seaweed industry.

Few people on campus realize that one of the world’s top seaweed strain-improvement laboratories is tucked away in Richards Hall. For the past fifteen years, Northeastern’s Seaweed Biotechnology Laboratory has genetically improved more than half a dozen commercially valuable seaweeds and has brought in over $2.1 million in support and three patents.

What makes our laboratory perhaps the best in its field is its invention and successful application of modern biotechnological and genetic-improvement techniques. For example, a scientist from the Philippines came to us a year ago to learn how to produce new strains of a marine alga called Kappaphycus. Kappaphycus has replaced Irish moss as the world’s principal source of carrageenan and is widely aquacultured in the Philippines and Indonesia, providing the only source of income for many poor, rural regions in both countries.

But Kappaphycus growers in the Philippines had lately suffered dramatic losses in their harvests. So the Southeast Asian Fisheries Development Center asked us to help develop new Kappaphycus strains that would be more resistant to disease and more apt to flourish. Through a combination of mutagenesis and strain selection, three promising new strains have already been produced. It’s nice to think that plants produced on Huntington Avenue may improve the lives of people half the world away.

Another example closer to home concerns the strain improvement of the world’s most widely eaten seaweed, Porphyra. More commonly known as nori, Porphyra is the dark, purple-black wrapper around sushi—a food very popular in Japan, China, Taiwan, and Korea, and increasingly popular in Europe and the United States (including at the food court in Northeastern’s student center).

About ten years ago, Coastal Plantations International (which later changed its name to Phycogen) began farming Porphyra in Cobscook Bay, in the northern part of Maine. The company hoped to create a high-grade domestic source of nori, in a region economically depressed by fishing closures.

However, the strain Coastal Plantations tried to grow didn’t produce a satisfactory yield two out of the three summers it was farmed. So they turned to us. Within two years, we had produced a new strain that was more robust and faster growing than the parental plant—so much better, in fact, that they called it “super nori.”

Produced by a technique we patented, known as protoplast fusion, our super-nori strain is the result of literally fusing together two cells whose cell walls have been removed. Super nori has twice the amount of DNA as one of its parental cells, which is why it grows faster and can produce higher yields of valuable products. And because it contains only the parent plant’s DNA—no so-called foreign DNA—it does not pose a threat to the environment. (Unfortunately, not long after the super-nori strain was produced, Phycogen closed their nori farming operations in Maine due to the recent downturn in the investment environment.)

What’s next for our laboratory? Right now, we’re working on something that could help save the fish aquaculture industry and at the same time reduce coastal pollution.

Although consumers’ demand for fish is greater than ever, fish aquaculture is facing significant obstacles. Even though the harvest of wild populations is now steadily decreasing, the industry has been criticized for using wild fish species to make the fish meal fed to farmed fish. It’s also seen as a source of nutrient pollution in coastal environments; all animal-production facilities, including fish hatcheries and farms, will soon have to meet new nutrient-discharge standards.

We’re working with a Maine company to develop a land-based polyculture system that would grow our super-nori strain on the nutrients in the wastewater from a fish aquaculture facility (thus remediating it) and simultaneously producing a nutrient-rich supplemental food that can be fed back to the fish.

And we’re also researching the nutritional benefits of our super-nori strain. Our laboratory’s recent collaboration with carotenoid experts at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University and fatty-acid experts at a private company has shown that our super-nori strain is not only rich in such vitamins as C (the same amount an orange contains), B1, B2, B12, and folic acid, but also in the antioxidants beta-carotene (the same amount a carrot contains) and lutein, and several polyunsaturated fatty acids (PUFAs), including the omega-3 fatty acid eicosapentaenoic acid (EPA).

Recent news items have reported on the health benefits of having beta-carotene, lutein, and omega-3 fatty acids (like EPA) in your diet. Medical research suggests that beta-carotene and lutein can reduce the risk of certain cancers, coronary disease, and blindness, and that omega-3 fatty acids can provide cardiovascular, anti-arthritis, and brain-development benefits.

Since fish also require high amounts of omega-3 fatty acids and other PUFAs, especially in their early development, we believe super nori could be an extremely healthful replacement for fish oils in their diet, too.

If our polyculture concept is successful, we hope every land-based fish-farming facility will start growing our super nori. Maybe we should rename the strain: How does “new nori”—I mean, “NU nori”—sound?

Donald Cheney, director of the Seaweed Biotechnology Laboratory, is an associate professor of biology.