Microfungi for biorefinery and recycling

Purpose and goal

The aim was to cultivate the edible, filamentous micro-fungus Rhizopus oryzae in industrial side-streams for sustainable use in fish feed. We have adjusted the protein rich side-stream from starch production out of potato (Potato Protein Liquor, PPL) at the Tings Nöbbelöv plant for selective cultivation of our fungus with concomitant reduction of environmental contamination. Harvest, dewatering and drying of the fungal biomass was done with equipment already available at the plant. The cost of goods (COG) is competitive, and the process seems ready for the industry.

Expected results and effects

Cultivation in PPL caused problems including foaming, pH increase, and contamination, which came under control by adjustment of the cultivation conditions. Such changes also made possible near sterile cultivation in PPL without preceding sterilization, which saves a lot of energy. Also the easy harvest, dewatering, and drying do not consume much energy. We have reached high crude protein (CP) values at the same level as prime quality Norse LT94 fishmeal being higher than what seemed possible at the start of the project and in great demand by the fish feed industry.

Planned approach and implementation

The project was guided by experiences from cultivation in spent sulphite liquor (SSL), however, new challenges appeared with PPL as foaming, contamination, and pH-increase. After mastering these difficulties the fungal biomass showed very good properties with respect to production and feed. There is an intrinsic advantage of PPL being based on a food production process. The challenges also brought about cost-containing technical improvements. There is now a `testing system´ for new sources to sustainable production of a fish feed adapted to the environment. The demand is great.