BIOFEED - Novel salmon feed by integrated bioprocessing of non-food biomass

Novel feeds for Norwegian salmon produced from trees and seaweed through a biorefinery processing technology To optimize the production of yeast, processing technology needs to be developed to efficiently convert tree biomass and seaweeds (SW) into high quality and safe feed resources. Several process parameters have been optimized, including pre-treatment of the blue and green biomasses, enzymatic hydrolysis, composition of fermentation media, fermentation conditions, selection of microbial strain, down-stream processing, and nutritional and functional evaluation of the microbial products. BIOFEED has invested in biorefinery infrastructure and expertise in bioprocessing and fermentation at NMBU, in collaboration with other projects. NMBU's Biorefinery facility is run routinely from hydrolysis of the blue and green biomasses to down-stream processing of yeast. Milled brown seaweeds have been efficiently hydrolyzed to fermentable sugars using a mixture of commercial alginate lyase and a cellulase cocktail. Research has focused on finding optimal combinations of enzymes and conditions for seaweed processing and on in-house production of several hydrolysing enzymes (e.g. cellulases and alginate lyases). Inclusion of various alginate lyases resulted in lower viscosity and increased availability of the substrate for further enzymatic treatment, leading to higher sugar yield in the fermentation medium. The growth rate and protein content of selected yeast strains were evaluated on a simple medium consisting of a mixture of seaweed and spruce hydrolysates from Borregaard. Supplementing the fermentation medium with ammonia resulted in increased yield and increased protein content. An important goal was also to increase the productivity and protein content of yeast by reducing the effect of inhibitors in the medium. Various dosing strategies and substrate conditions have been tested in the fermenter, and the results show that there are good opportunities to achieve a more efficient process. Scaling up the process to 30-litre pilot scale was carried out using Candida utilis yeast. The nutritional value of yeast may vary depending on the species, fermentation process and downstream processing conditions. Drying and downstream processing of yeast can have an impact on both nutritional quality and health beneficial properties, thus down-stream processing experiments have been performed to improve the nutritional value as well as the bioactivity of the yeast products. Down-stream processing by autolysis gave highest digestibility values, while spray-drying alone gave the lowest values. Yeast has been fed to salmon in freshwater and seawater in several in vivo studies. In general, the results show that fish perform well and had improved gut health when fed yeast-based diets compared to a challenging soy-based diet or a conventional plant-based diet. Improved gut health was documented by demonstrating improved gut barrier function, reduced inflammation, and a stimulation of the innate immunity. Thus, our results show that yeast produced from spruce trees is a promising protein source with health-beneficial properties. Feeding Norwegian White lamb 2.5 or 5% SW gave similar growth performance and carcass quality of lamb compared to a total mixed ration with concentrate and grass silage. SW also resulted in a more tender meat with lower cooking loss and with a unique taste and with increased levels of iodine. Feeding SW did not affect the microbiota composition in the rumen based on 16S rDNA sequencing. The BIOFEED project has also provided important methods and tools that have been essential for succeeding with the research on novel feed resources in the Centre for research based innovation, Foods of Norway. Cultivation conditions of SW to reach optimal biomass production and high sugar yield have also been evaluated. Seaweed cultivation for use in biorefinery processes requires an in-depth understanding of the chemical composition of the SW, as affected by locality, environment, depth, and seasonal variations. SW biomass grown at 3 m depth and harvested in June was found to be most suitable for biorefinery processing. To evaluate the environmental impact of seaweed cultivation and to identify key knowledge gaps, a review article entitled "The environmental risks associated with the development of seaweed farming in Europe - prioritizing key knowledge gaps" based on available literature and data from Seaweed Energy Solutions and the Scottish Association of Marine Sciences was published in Frontiers in Marine Science. Further, we have also recently published a review article entitled "Marine macroalgae as a source of protein and bioactive compounds in feed for monogastric animals" in the Journal of the Science of Food and Agriculture.

The project has created an important foundation for future research and development of novel feed resources in academia and industry, including in the Centre for research-based innovation, Foods of Norway. Examples of important achievements can be found in the main report. Overall, the project has made a major contribution to the development of new sustainable feed resources. This will open new market channels for the forest industry, seaweed cultivation industry and, by developing sustainable feed resources, the project has made a major contribution to ensuring further growth and competitiveness in the aquaculture industry. The achievements obtained in BIOFEED also have relevance for the Norwegian agriculture industry and for improving national food security.

Synopsis: In this project we will explore the use of non-food biomass from wood (spruce) and macroalgae in feed for Atlantic salmon, either directly (protein from macroalgae) or, primarily, by generating sugar streams that are used to produce protein- and /or lipid-rich microbial biomass as feed ingredients. We will address pre-processing techniques, enzymatic hydrolysis, screening of promising microorganisms (primarily yeasts), and evaluate downstream processing methods. The potential feed ingredients thus produced, will be evaluated for nutritional and functional properties and we will document effects on performance, nutrient retention, and gastro-intestinal health of Atlantic salmon. Ecological and economical aspects of using forest resources and large-scale cultivation of macroalgae for fish feed will also be investigated. The project will be conducted in close collaboration with Norway's leading biorefinery (Borregaard), a commercial seaweed grower (Seaweed Energy solutions), and international partners including SLU that have a large collection of isolated and characterized yeast strains, and a major enzyme producer, Novozymes. The project will be aligned with several ongoing projects.