Until recently, scientists search for a good waterproof glue which doesnt pollute the environment or cause illnesses in people had gone unfulfilled. But a team of researchers in Idaho discovered that the quest for a better adhesive may end in a common shellfish that we eat on a regular basis.
Super glue from seafood?
Most people think of the blue mussel, or Mytilus edulis, as a dinner course in a seafood restaurant. But Frank Roberto, a researcher at the Idaho National Engineering and Environmental Lab (INEEL), sees this small member of the mollusk phylum as a source of superstrong, waterproof glue.
Roberto and his team noted how strongly these mollusks attached to surfaces. "Usually you see them on the pilings for piers or on the surface of rocks that are found at the tidal interface," he says. "We know from the pioneering work of Dr. Herbert Waite, whos now at the University of California–Santa Barbara, there are at least five different proteins that are used by the mollusk to produce these natural adhesive structures."
Roberto and his team focused on protein structures known as byssal threads in his investigation, and realized that they could make a strong, waterproof adhesive.
Problems, and a solution.
The problem was that Roberto had to use 10,000 mussels to produce just one gram of this natural super glue, at a cost of $75,000 per gram. Furthermore, private companies interested in exploring uses for the new biological compound would want several kilograms of the glue (a kilogram is about 2.2 pounds), and one kilogram would have cost $75 million dollars.
"We calculated [that] from 10,000 mollusks per gram to make a thousand grams, which is a kilogram, that would be 10 million mussels," says Roberto, jokingly adding, "That might reduce the supply available for those of us who like to eat mussels."
So the INEEL team decided to use recombinant DNA technology to clone the genes responsible for making the adhesive proteins and transfer them to a cheaply-grown organism—brewers yeast. It worked.
"Within a week, weve isolated more protein [from the yeast] than we can get from tens of thousands of mollusks," says Roberto.
What Are the Advantages of Mussel Glue?
Another big advantage to using mussel glue is that it wont pollute the environment like current waterproof adhesives which use formaldehyde, another source of toxicity in humans. This could lead to the use of mussel adhesive in manufacturing environmentally friendly plywood, wood veneers, particle board and other wood products.
|Mussel glue could aid orthodontists.|
image: American Dental Association
"We dont believe there any drawbacks to using this glue," Roberto states. "I think there is a lot of attractiveness to using natural adhesives." Possible medical uses for a non-toxic, biological glue include surgery, suturing, orthodontics and opthalmics.
The U.S. Navy, which was initially interested in Robertos work, envisions military uses of mussel adhesives. "Of course you can think of battlefield applications: applying mines or satchel charges to surfaces underwater," says Roberto. "But they also need waterproof adhesives for a variety of naval applications, from. . . repair of ships underwater to attachment of sensors and other materials to the hulls of ships."
|Mussels can attach themselves where they are not wanted.|
image: New York Sea Grant
On top of that, the effort to study how mussels attach themselves may prove useful to control unwanted mussel populations. The blue mussels relative, the zebra mussel, causes big headaches for ship owners, dock masters, power plant operators and biologists wherever the tiny shellfish attach themselves. Zebra mussels, which were accidently introduced into the Great Lakes region in the mid-1980s, clog water intakes, compete with native species for food, and may contribute to an increase in blue-green algae in fresh-water lakes.
By using reverse genetics, researchers hope to persuade the zebra mussel and other mollusks to stay away from hulls, piers, and other places where they cause a nuisance or interfere with local ecologies. Roberto believes that "understanding how these natural adhesives work could suggest ways to circumvent or counteract attachment of these natural organisms."
How long until I can buy mussel glue at the store?
Roberto estimates that commercially available glues based on mussel attachment proteins will become available in three to five years. "Right now the real limitation is sufficient supply of the adhesive proteins so that we can actually provide them to adhesive manufacturers who are interested in applications," he says.
Elsewhere on the web:
Great Lakes Battle with the Zebra Mussel
Department of Energy?Mussel Information
NASA Mussel Glue