Seaweeds grow abundantly, and are relatively little affected by harmful environmental impact, along Swedish coasts. At the same time, there is a huge demand for sustainable foods, alternative food sources and new sources for a biological production of fuels and chemicals.
As part of a larger project, funded by the Swedish Foundation for Strategic Research, researchers at the Department of Biology and Biological Engineering took a closer look at the green seaweed Ulva lactuca
, also known as sea lettuce.
Suitable for foods and pharmaceuticals
“Ulva biomass consists of a full range of various biomolecules. The quality of Ulva and its subsequent applications greatly depend on the waters in which it is grown. As the western Swedish coastline is to a large extent free of toxic metals and pollutants, the Ulva biomass that we obtain from these sea waters is suitable for food and medical applications,” says Venkat Rao Konasani, a postdoc at the division of Industrial Biotechnology, and continues:
“Ulva biomass from the algal blooms that are found in eutrophicated waters, rich in phosphorous, pollutants and toxic metals, is not suitable for food. However, this algal bloom biomass would be a good choice for bio-energy applications.”
In Ulva, there’s a carbohydrate and polysaccharide called ulvan, which is rather different to anything found on land. Ulvan has features that make it relatively easy to dissolve, compared to most other polysaccharides.
“We also find more unusual and interesting sugars. They could be used as building blocks in a chemical synthesis to make heparin, a drug used to treat blood clots, thereby providing an alternative to heparin produced from animal sources. They could also, for example, be used as a starter molecule for flavors, or for the production of sustainable materials,” says Associate Professor Eva Albers.
Enzymes to open up the cell wall
To use the nutrients and sugars found in seaweed, they must first be recovered. Seaweed consist of cells, with cell walls containing – among other things – the ulvan. The researchers aim to find ways of opening up the cell wall structure, as mildly as possible. Using enzymes has proved both efficient and environmentally friendly. Recently, the research group at BIO identified a completely new and promising subgroup of the enzyme group ulvan lyase, which cleaves the ulvan.
“Two subgroups are earlier described, and we have found a third. We have also been able to describe yet another enzyme of one of the other subgroups, which comes from the same bacteria. Our findings give us new ways of processing biomass for industrial purposes,” Eva Albers says.
The new enzyme subgroup is also shown to have an unexpected advantage; it is naturally present in two groups of bacteria, found in our gastric/intestinal tract.
Possible to digest
“Researchers ask the question: Could we eat seaweed? Is it possible for us to take advantage of seaweed’s nutritional value? Our findings indicate that we can probably digest and absorb nutrients from seaweed, with help of our own intestinal bacteria breaking the cell walls. In other words, seaweed could possibly serve as a new, future source of nutrition,” Eva Albers says, and Venkat Rao Konasani concludes:
“This finding brings forward the potential of Ulva and opens for new commercial high-value applications of the algae biomass which is abundant in Swedish coastal waters, and otherwise unused.”
Text: Mia Malmstedt
Photo: Martina Butorac