Forests make up about half of our land area (14 million hectares). Logging amounts to approximately 10 million cubic meters per year. The gap between harvest and growth is increasing, and there is potential to utilize more trees without affecting the environment negatively.
To create the yeast from coniferous trees, technology based on thermo-chemical processes are needed to separate the tree fibers into the main constituents - lignin, cellulose and hemicellulose. Cellulose and hemicellulose are made up of sugar chains with hexose (glucose and mannose) and pentose sugars (xylanose and arabinose). Lignin is a complex molecule with special properties that can be used for a wide-range of high-value products. Enzyme technology is then used to convert the cellulose and hemicellulose into sugars. Lastly, fermentation technology through the use of special yeast strains, as well as downstream processing biomass, is used to produce yeast which is used as a high quality protein-rich feed ingredient for fish.
Other species of trees such as birch can also be used in this process, but this would require different pre-processing technologies in order to convert the tree’s fibers into fermentable sugars for the production of yeast biomass.
As a high-quality protein source, the novel single-cell feed ingredient can partially or perhaps totally replace fish meal in the diets of farmed fish. Research at NMBU has already confirmed that the yeast produced from trees can successfully replace 40 per cent of the protein in fish meal in diets for Atlantic salmon. In our project, we aim to optimize the process along the entire value chain from tree to feed, so we can reduce the processing cost.
The research also aims to use other yeast strains that accumulate high levels of lipids - these yeasts can then also replace some of the lipid content in fish feed.
Although coniferous trees are abundant in Norway it is important that the harvest of trees for feed will be managed sustainably.