Microfungal biomass - a new fish feed ingredient

Microfungal biomass for fish feed – a nutritious, environmentally friendly, and sustainable alternative The biotech company Cewatech, Gothenburg has developed a technology based on cultivation of micro-fungi called zygomycetes on side products from the paper pulp industry. Now the technology has reached pilot scale in a joint project with Nordic Paper in Säffle, western Sweden. The fungus is using the sugars in the paper pulp cooking liquid for growth. Initially the fungus was cultivated from the Indonesian food Tempe which is similar to tofu or camembert. The fungal biomass produced is rich in protein, fat, amino sugars, and vitamins which makes it suitable as a fish feed ingredient particularly as the amino acid composition is close to that of fishmeal. Structurally zygomycetes have a cell wall (exoskeleton) which is rich in chitosan/chitin. In this way they are similar to shellfish whose exoskeleton is based on chitin. Shellfish is often the dominant feed for salmonids, and planktonic crustacea are often a necessity for fry. The cell wall of zygomycetes is mechanically robust. When used for aquaculture feeding it is not likely to disintegrate until it reaches the gastric juices of a prey animal. In this way the nutrients of the zygomycetes biomass in feed would specifically become released in the gut of animals and minimize contamination of the environment. Feeding tests with rainbow trout (Mydland, Landsverk, Zimonja, Kiessling, Edebo, Storebakken), salmon (Kaszowska, Schlechtriem, Brännäs, Edebo, Kiessling, Bankefors, Pickova, Sandström), and arctic char (Brännäs, Andersson, Kiesslinig, Edebo) replacing part (10-30 %) of the fishmeal with fungal biomass have shown at least as good results as the control feed. The pilot plant in Säffle is producing fungal biomass quantities in hundreds of kilograms for further feeding tests and we hope to develop joint projects with fish feed producers in order to formulate the commercial product. The fungal biomass can also be developed into other products. As the Cewatech technology becomes integrated into the pulping process, also the value of the cooking liquid is enhanced. As a consequence the pulp mill is transferred into a ‘Biorefinery’ with fuller use of the raw material and improved profitability. Thus the possibilities for further expansion are good.