Kristoffer Stedt1, João P. Trigo2, Sophie Steinhagen1, Göran M. Nylund1, Bita Forghani2, Oscar Gustavsson1, Gunilla B. Toth1, Ingrid Undeland2, Henrik Pavia1
1Department of Marine Sciences, Tjärnö Marine Laboratory, University of Gothenburg
2Department of Biology and Biological Engineering – Food and Nutrition Science, Chalmers University of Technology
There is an increasing demand for sustainably produced protein-rich and nutritious food. Seaweeds are promising protein sources for the future if their protein content can be optimized. Cultivation of seaweeds in integration with fish farms has received much attention lately, but using other nutrient-rich process waters as cultivation media for seaweeds has rarely been studied. We explore the possibility for an industrial symbiosis between food production processing industries and seaweed cultivation. From initial experiments we show that both growth and crude protein content of the green seaweeds Ulva fenestrata, Ulva intestinalis and Chaetomorpha linum were significantly increased when cultivated in a wide range of different process waters, ranging from the production of herring, shrimp, salmon and oat. When upscaling the experiment with U. fenestrata and two selected herring production process waters, we managed to increase the biomass yield four to six times and crude protein content three times (> 30 % dry weight vs. 10 % dry weight) compared to U. fenestrata cultivated in seawater. The herring production process waters also significantly increased all essential amino acids in the seaweed biomass. Furthermore, the heavy metal content (arsenic, mercury, lead, and cadmium) in the biomass was well below the maximum allowed levels in foodstuff set by the European Commission. Combined, the results show that there is great potential for the symbiosis between the cultivation of seaweeds in food production process waters to produce sustainable proteins for the growing world population.