This study explores the potential valorization of brewer's spent grain (BSG) by Schizophyllum commune as an alternative low-cost and sustainable feedstock to produce fungal biomass rich in bioactive compounds and exopolysaccharides (EPS). Submerged cultures were performed in a 6 l bioreactor achieving maximum values of 9.8 g/l biomass and 7.3 g/l EPS with BSG as the substrate. Compared with traditional glucose-based culture media, BSG led to a 1.9-fold increase in biomass and a 2.3-fold increase in EPS production. The biomass produced was rich in protein (21.4 % w/w d.w) and β-glucans (44.6 % w/w d.w). The β-glucans content in the EPS was 44.1 %, however, it was much lower for α-glucans (0.5 %). 1H NMR, FTIR and Raman spectrometry revealed the characteristic peaks of β-glucans and TGA analysis showed the high thermal stability of the EPS. Particle tracking microrheology and viscometry showed that the produced EPS displayed power-law viscoelasticity and shear-thinning behavior respectively. These characteristics became stronger as concentration increased. The gel strength and elasticity were stronger for the EPS from BSG. This study represents the first comprehensive report of using unrefined brewer's spent grain as the sole carbon source for S. commune EPS production with detailed viscoelastic characterization, establishing a circular bioeconomy approach that advances the potential of fungal biopolymers for industrial biotechnology.
Keywords: Bioeconomy; Biopolymer; Circular; Exopolysaccharide; Fungi; Glucan; Rheology.
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