NordForsk: Mushroom-based processes for increased local production of non-meat protein and enhanced agriculture sustainability

In this project we try to contribute to the agriculture sustainability by producing food from crop residues. The food to be produced is edible mushrooms, which are cultivated on crop residues and forestry residues. When edible mushrooms are harvested, a solid waste known as spent mushroom substrate (SMS) is generated. SMS is accumulated in large amounts, and it causes environmental problems. In the project, we investigate various alternatives for SMS valorization. SMS valorization is important for sustainable mushroom production. During the first year of the project (2023), we started experiments on mushroom cultivation, recovery of bioactive compounds and sugars from SMS, and using SMS as a biofertilizer. Researchers of the Swedish University of Agricultural Sciences (SLU) produced mushrooms from waste plant biomass. Two different types of mushrooms, namely shiitake and oyster mushrooms, were produced. SLU researchers investigated the suitability of different residues as substrates for mushroom cultivation. In their experiments, the yield of mushrooms was determined. The quality of the produced mushrooms was assessed by determining the content of proteins and amino acids. At Inland Norway University for Applied Sciences, we evaluated the potential of SMS as a source of bioactive compounds. The chemical composition of SMS was analyzed. Bioactive compounds were extracted using conventional methods and advanced techniques. Polyphenols and carbohydrates are the bioactive compounds that were extracted and quantified. The antioxidant activity of the extracts was evaluated. The residues after extraction were used for producing sugars using enzymes. Researchers from Inland Norway University for Applied Sciences and University of Tartu started the tests of using SMS as biofertilizer. A preliminary evaluation of SMS as biofertilizer for spinach and ryegrass was performed. A study of the microbial communities in SMS was started. The study aimed at looking for microbes with potential to increase the amount of nitrogen in SMS. If the nitrogen content in SMS is increased, its value as biofertilizer will be enhanced. During the coming year (2024), the SMS sugars will be used for producing microbial oil and biopolymers and the studies on using SMS in wastewater bioremediation will start. Furthermore, bioactive compounds will be extracted with new methods, and the biofertilization experiments will continue.

MUSA intends to contribute to enhancing agriculture sustainability by (i) using crop residues for producing edible fungi, and (ii) upgrading spent mushroom substrate (SMS), the main by-product of mushroom farming, for uses supporting food production, substitution of mineral fertilizers and providing wastewater bioremediation solutions. The Norwegian researchers participating in the project will (i) extract bioactive compounds from SMS, (ii) investigate the enzymatic conversion of cellulose contained in SMS, (iii) prepare cellulosic hydrolysates to be used for cultivating oleaginous yeasts, (iv) recovery of lignin from SMS saccharification residues using green solvents, (v) assess SMS as biofertilizer and soil amendment, and (vi) evaluate the effects of using SMS-based wastewater bioremediation on freshwater ecosystems. The project will develop extraction methods that preserve the properties of targeted compounds and minimize degradation of non-targeted molecules. The extracts will be evaluated as food additives, and the extraction residue will be subjected to saccharification for producing sugars that will serve as substrates for oleaginous yeasts. The produced yeast will be directed to extraction of lipids that can contribute to decrease the environmental impact of production of palm-, soybean- and rapeseed oil. The lipid-free biomass will be subjected to extraction of carotenoids and ß-glucans, which are bioactive compounds with antioxidant and immunostimulant activity. The agronomic benefits of using of SMS as a biofertilizer in horticulture or as a soil amendment in agriculture will be quantified. Microbial communities in SMS, and correlations between specific microbes and SMS effectivity as biofertilizer will be assessed. A bioremediation approach using SMS for removal micropollutants from wastewater to be used for irrigation will be developed. The SMS effects on water quality indicators will be addressed, and its impact on water ecosystems will be elucidated.